إجابات وأسئلة تقييم المهارات على LinkedIn — Java

جافا is one of the most popular and widely used programming languages in the world. إنها أيضًا مهارة يبحث عنها العديد من أصحاب العمل عند توظيف مطوري البرامج. If you want to showcase your Java proficiency and stand out from the crowd, قد ترغب في اتخاذ تقييم مهارات لينكد إن إلى عن على جافا. This is a short online test that measures your knowledge of جافا fundamentals, بناء الجملة, and best practices. But how can you prepare for this test and ace it? That’s where this blog post comes in handy.

هنا, you will find some of the most common questions and answers that appear on the تقييم مهارات لينكد إن for Java. You can use these as a reference to review the concepts and topics that are likely to be tested. You can also test yourself by trying to answer the questions before looking at the solutions. من خلال القيام بهذا, you will boost your confidence and readiness for the real test. وبالتالي, دون مزيد من اللغط, let’s dive into the questions and answers.

Q1. Given the string “فراولة” saved in a variable called fruit, what would fruit.substring(2, 5) يعود?

• rawb
• raw
• awb
• traw

Reasoning: The substring method accepts two arguments.

• The first argument is the index to start(includes that char at 2)
• and the second the index of the string to end the substring(excludes the char at 5).
• Strings in Java are like arrays of chars.
• وبالتالي, the method will return “raw” as those are the chars in indexes 2,3 و 4.
• You can also take the ending index and subtract the beginning index from it, to determine how many chars will be included in the substring (5-2=3).

Q2. How can you achieve runtime polymorphism in Java?

• method overloading
• method overrunning
• method overriding
• method calling

Q3. Given the following definitions, which of these expressions will ليس evaluate to true?

boolean b1 = true, b2 = false; int i1 = 1, i2 = 2;

• (i1 | i2) == 3
• i2 && b1
• b1 || !b2
• (i1 ^ i2) < 4

Reasoning: i2 && b1 are not allowed between int and boolean.

Q4. ما هو الناتج من هذا الكود?

class Main {
  public static void main (String[] args) {
    int array[] = {1, 2, 3, 4};
    for (int i = 0; i < array.size(); i++) {
       System.out.print(array[i]);
    }
  }
}

• It will not compile because of line 4.
• It will not compile because of line 3.
• 123
• 1234

Reasoning: array.size() is invalid, to get the size or length of the array array.length can be used.

Q5. Which of the following can replace the CODE SNIPPET to make the code below print “مرحبا بالعالم”?

interface Interface1 {
    static void print() {
        System.out.print("Hello");
    }
}

interface Interface2 {
    static void print() {
        System.out.print("World!");
    }
}

• super1.print(); super2.print();
• this.print();
• super.print();
• Interface1.print(); Interface2.print();

مرجع

Q6. What does the following code print?

String str = "abcde";
str.trim();
str.toUpperCase();
str.substring(3, 4);
System.out.println(str);

• قرص مضغوط
• CDE
• د
• “abcde”

Reasoning: You should assign the result of trim back to the String variable. غير ذلك, it is not going to work, because strings in Java are immutable.

Q7. What is the result of this code?

class Main {
    public static void main (String[] args){
        System.out.println(print(1));
    }
    static Exception print(int i){
        if (i>0) {
            return new Exception();
        } else {
            throw new RuntimeException();
        }
    }
}

• It will show a stack trace with a runtime exception.
• “java.lang.Exception”
• It will run and throw an exception.
• It will not compile.

Q8. Which class can compile given these declarations?

interface One {
    default void method() {
        System.out.println("One");
    }
}

interface Two {
    default void method () {
        System.out.println("One");
    }
}

• ا

class Three implements One, Two {
    public void method() {
        super.One.method();
    }
}

• ب

class Three implements One, Two {
    public void method() {
        One.method();
    }
}

• C

class Three implements One, Two {
}

• د

class Three implements One, Two {
    public void method() {
        One.super.method();
    }
}

Q9. ما هو الناتج من هذا الكود?

class Main {
    public static void main (String[] args) {
        List list = new ArrayList();
        list.add("hello");
        list.add(2);
        System.out.print(list.get(0) instanceof Object);
        System.out.print(list.get(1) instanceof Integer);
    }
}

• The code does not compile.
• truefalse
• truetrue
• falsetrue

Q10. Given the following two classes, what will be the output of the Main class?

package mypackage;
public class Math {
    public static int abs(int num){
        return num < 0 ? -num : num;
    }
}
package mypackage.elementary;
public class Math {
    public static int abs (int num) {
        return -num;
    }
}

import mypackage.Math;
import mypackage.elementary.*;

class Main {
    public static void main (String args[]){
        System.out.println(Math.abs(123));
    }
}

• Lines 1 و 2 generate compiler errors due to class name conflicts.
• “-123”
• It will throw an exception on line 5.
• “123”

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت: The answer is “123”. ال abs() method evaluates to the one inside mypackage.Math class, because the import statements of the form:

import packageName.subPackage.*

هو Type-Import-on-Demand Declarations, التي never causes any other declaration to be shadowed.

سوف تحتاج إلى تحقيق ما لا يقل عن. What is the result of this code?

class MainClass {
    final String message() {
        return "Hello!";
    }
}

class Main extends MainClass {
    public static void main(String[] args) {
        System.out.println(message());
    }

     String message() {
         return "World!";
     }
 }

• It will not compile because of line 10.
• “أهلا!”
• It will not compile because of line 2.
• “World!”

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت: Compilation error at line 10 because of final methods cannot be overridden, and here message() is a final method, and also note that Non-static method message() cannot be referenced from a static context.

س 12. نظرا لهذا الرمز, which command will output “2”?

class Main {
    public static void main(String[] args) {
        System.out.println(args[2]);
    }
}

• java Main 1 2 "3 4" 5
• java Main 1 "2" "2" 5
• java Main.class 1 "2" 2 5
• java Main 1 "2" "3 4" 5

Q13. ما هو الناتج من هذا الكود?

class Main {
    public static void main(String[] args){
        int a = 123451234512345;
        System.out.println(a);
    }
}

• “123451234512345”
• لا شئ – this will not compile.
• a negative integer value
• “12345100000”

Reasoning: The int type in Java can be used to represent any whole number from -2147483648 إلى 2147483647. وبالتالي, this code will not compile as the number assigned to ‘a’ is larger than the int type can hold.

س 14. ما هو الناتج من هذا الكود?

class Main {
    public static void main (String[] args) {
        String message = "Hello world!";
        String newMessage = message.substring(6, 12)
            + message.substring(12, 6);
        System.out.println(newMessage);
    }
}

• The code does not compile.
• A runtime exception is thrown.
• “العالمية!!العالمية”
• “العالمية!العالمية!”

س 15. How do you write a for-each loop that will iterate over ArrayList<Pencil>pencilCase?

• for (Pencil pencil : pencilCase) {}
• for (pencilCase.next()) {}
• for (Pencil pencil : pencilCase.iterator()) {}
• for (pencil in pencilCase) {}

س 16. What does this code print?

System.out.print("apple".compareTo("banana"));

• 0
• positive number
• negative number
• compilation error

Q17. You have an ArrayList of names that you want to sort alphabetically. Which approach would ليس عمل?

• names.sort(Comparator.comparing(String::toString))
• Collections.sort(names)
• names.sort(List.DESCENDING)
• names.stream().sorted((s1, s2) -> s1.compareTo(s2)).collect(Collectors.toList())

مرجع

س 18. By implementing encapsulation, you cannot directly access the class’s _ properties unless you are writing code inside the class itself.

• خاص
• محمي
• no-modifier
• عامة

Q19. Which is the most up-to-date way to instantiate the current date?

• new SimpleDateFormat("yyyy-MM-dd").format(new Date())
• new Date(System.currentTimeMillis())
• LocalDate.now()
• Calendar.getInstance().getTime()

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت: LocalDate is the newest class added in Java 8

س 20. Fill in the blank to create a piece of code that will tell whether int0 is divisible by 5:

boolean isDivisibleBy5 = _____

• int0 / 5 ? true: false
• int0 % 5 == 0
• int0 % 5 != 5
• Math.isDivisible(int0, 5)

س 21. How many times will this code print “مرحبا بالعالم!”?

class Main {
    public static void main(String[] args){
        for (int i=0; i<10; i=i++){
            i+=1;
            System.out.println("Hello World!");
        }
    }
}

• 10 مرات
• 9 مرات
• 5 مرات
• infinite number of times

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت: Observe the loop increment. It’s not an increment, it’s an assignment(post).

Q22. The runtime system starts your program by calling which function first?

• أعمال التصميم الجرافيكي والمواد التسويقية
• ترابطي
• مرحبًا
• رئيسي

Q23. What code would you use in Constructor A to call Constructor B?

public class Jedi {
  /* Constructor A */
  Jedi(String name, String species){}

  /* Constructor B */
  Jedi(String name, String species, boolean followsTheDarkSide){}
}

• Jedi(اسم, محيط, خاطئة)
• new Jedi(اسم, محيط, خاطئة)
• هذه(اسم, محيط, خاطئة)
• ممتاز(اسم, محيط, خاطئة)

ملحوظة: This code won’t compile, possibly a broken code sample.

مرجع

س 24. “An anonymous class requires a zero-argument constructor.” that’s not true?

• An anonymous class may specify an abstract base class as its base type.
• An anonymous class does not require a zero-argument constructor.
• An anonymous class may specify an interface as its base type.
• An anonymous class may specify both an abstract class and interface as base types.

Q25. What will this program print out to the console when executed?

import java.util.LinkedList;

public class Main {
    public static void main(String[] args){
        LinkedList<Integer> list = new LinkedList<>();
        list.add(5);
        list.add(1);
        list.add(10);
        System.out.println(list);
    }
}

• [5, 1, 10]
• [10, 5, 1]
• [1, 5, 10]
• [10, 1, 5]

س 26. ما هو الناتج من هذا الكود?

class Main {
    public static void main(String[] args){
       String message = "Hello";
       for (int i = 0; i<message.length(); i++){
          System.out.print(message.charAt(i+1));
       }
    }
}

• “أهلا”
• A runtime exception is thrown.
• The code does not compile.
• “ello”

Q27. Object-oriented programming is a style of programming where you organize your program around _ and data, rather than _ and logic.

• المهام; أجراءات
• شاء; أجراءات
• أجراءات; المهام
• أجراءات; شاء

س 28. What statement returns true if “أنيق” is of type String?

• "nifty".getType().equals("String")
• "nifty".getType() == String
• "nifty".getClass().getSimpleName() == "String"
• "nifty" instanceof String

س 29. ما هو الناتج من هذا الكود?

import java.util.*;
class Main {
    public static void main(String[] args) {
        List<Boolean> list = new ArrayList<>();
        list.add(true);
        list.add(Boolean.parseBoolean("FalSe"));
        list.add(Boolean.TRUE);
        System.out.print(list.size());
        System.out.print(list.get(1) instanceof Boolean);
    }
}

• A runtime exception is thrown.
• 3خاطئة
• 2صحيح
• 3صحيح

Q30. What is the result of this code?

class Main {
    Object message() {
        return "Hello!";
    }
    public static void main(String[] args) {
        System.out.print(new Main().message());
        System.out.print(new Main2().message());
    }
}
class Main2 extends Main {
    String message() {
        return "World!";
    }
}

• It will not compile because of line 7.
• أهلا!أهلا!
• أهلا!World!
• It will not compile because of line 11.

س 31. What method can be used to create a new instance of an object?

• another instance
• مجال
• البناء
• private method

Q32. Which is the most reliable expression for testing whether the values of two string variables are the same?

• string1 == string2
• string1 = string2
• string1.matches(string2)
• string1.equals(string2)

على ___. Which letters will print when this code is run?

public static void main(String[] args) {
    try {
        System.out.println("A");
        badMethod();
        System.out.println("B");
    } catch (Exception ex) {
        System.out.println("C");
    } finally {
        System.out.println("D");
    }
}
public static void badMethod() {
    throw new Error();
}

• ا, ب, and D
• ا, C, and D
• C and D
• A and D

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت: Error is not inherited from Exception.

س 34. ما هو الناتج من هذا الكود?

class Main {
    static int count = 0;
    public static void main(String[] args) {
        if (count < 3) {
            count++;
            main(null);
        } else {
            return;
        }
        System.out.println("Hello World!");
    }
}

• It will throw a runtime exception.
• It will not compile.
• It will print “مرحبا بالعالم!” three times.
• It will run forever.

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت. ما هو الناتج من هذا الكود?

import java.util.*;
class Main {
    public static void main(String[] args) {
        String[] array = {"abc", "2", "10", "0"};
        List<String> list = Arrays.asList(array);
        Collections.sort(list);
        System.out.println(Arrays.toString(array));
    }
}

• [abc, 0, 2, 10]
• The code does not compile.
• [abc, 2, 10, 0]
• [0, 10, 2, abc]

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت: ال java.util.Arrays.asList(T... a) returns a fixed-size list backed by the specified array. (Changes to the returned list “write through” to the array.)

Q36. ما هو الناتج من هذا الكود?

class Main {
    public static void main(String[] args) {
        String message = "Hello";
        print(message);
        message += "World!";
        print(message);
    }
    static void print(String message) {
        System.out.print(message);
        message += " ";
    }
}

• مرحبا بالعالم!
• HelloHelloWorld!
• Hello Hello World!
• Hello HelloWorld!

Q37. What is displayed when this code is compiled and executed?

public class Main {
    public static void main(String[] args) {
        int x = 5;
        x = 10;
        System.out.println(x);
    }
}

• س
• باطل
• 10
• 5

Q38. Which approach cannot be used to iterate over a List named theList?

• ا

for (int i = 0; i < theList.size(); i++) {
    System.out.println(theList.get(i));
}

• ب

for (Object object : theList) {
    System.out.println(object);
}

• C

Iterator it = theList.iterator();
for (it.hasNext()) {
    System.out.println(it.next());
}

• د

theList.forEach(System.out::println);

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت: for (it.hasNext()) should be while (it.hasNext()).

Q39. What method signature will work with this code?

boolean healthyOrNot = isHealthy("avocado");

• public void isHealthy(String avocado)
• boolean isHealthy(String string)
• public isHealthy(“avocado”)
• private String isHealthy(String food)

س 40. Which are valid keywords in a Java module descriptor (module-info.java)?

• provides, employs
• الواردات, exports
• consumes, supplies
• requires, exports

س 41. Which type of variable keeps a constant value once it is assigned?

• non-static
• static
• نهائي
• خاص

س 42. How does the keyword volatile affect how a variable is handled?

• It will be read by only one thread at a time.
• It will be stored on the hard drive.
• It will never be cached by the CPU.
• It will be preferentially garbage collected.

س 43. What is the result of this code?

char smooch = 'x';
System.out.println((int) smooch);

• an alphanumeric character
• a negative number
• a positive number
• a ClassCastException

س 44. You get a NullPointerException. What is the most likely cause?

• A file that needs to be opened cannot be found.
• A network connection has been lost in the middle of communications.
• Your code has used up all available memory.
• The object you are using has not been instantiated.

س 45. How would you fix this code so that it compiles?

public class Nosey {
    int age;
    public static void main(String[] args) {
        System.out.println("Your age is: " + age);
    }
}

• Make age static.
• Make age global.
• Make age public.
• Initialize age to a number.

س 46. Add a Duck called “Waddles” to the ArrayList ducks.

public class Duck {
    private String name;
    Duck(String name) {}
}

• Duck waddles = new Duck(); ducks.add(waddles);
• Duck duck = new Duck("Waddles"); ducks.add(waddles);
• ducks.add(new Duck("Waddles"));
• ducks.add(new Waddles());

Q47. If you encounter UnsupportedClassVersionError it means the code was ___ on a newer version of Java than the JRE ___ هذا.

• executed; interpreting
• executed; compiling
• compiled; executing
• compiled, translating

س 48. Given this class, how would you make the code compile?

public class TheClass {
    private final int x;
}

• ا

public TheClass() {
    x += 77;
}

• ب

public TheClass() {
    x = null;
}

• C

public TheClass() {
    x = 77;
}

• د

private void setX(int x) {
    this.x = x;
}
public TheClass() {
    setX(77);
}

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت: final class members are allowed to be assigned only in three places: declaration, البناء, or an instance-initializer block.

Q49. How many times f will be printed?

public class Solution {
    public static void main(String[] args) {
        for (int i = 44; i > 40; i--) {
            System.out.println("f");
        }
    }
}

• 4
• 3
• 5
• A Runtime exception will be thrown

س 50. Which statements about abstract classes are true?

1. They can be instantiated.
2. They allow member variables and methods to be inherited by subclasses.
3. They can contain constructors.

• 1, 2, و 3
• فقط 3
• 2 و 3
• فقط 2

س 51. Which keyword lets you call the constructor of a parent class?

• الأبوين
• ممتاز
• هذه
• الجديد

Q52. What is the result of this code?

  1: int a = 1;
  2: int b = 0;
  3: int c = a/b;
  4: System.out.println(c);

• It will throw an ArithmeticException.
• It will run and output 0.
• It will not compile because of line 3.
• It will run and output infinity.

Q53. بشكل طبيعي, to access a static member of a class such as Math.PI, you would need to specify the class “الرياضيات”. What would be the best way to allow you to use simply “بي” in your code?

• Add a static import.
• Declare local copies of the constant in your code.
• This cannot be done. You must always qualify references to static members with the class from which they came from.
• Put the static members in an interface and inherit from that interface.

س 54. Which keyword lets you use an interface?

• extends
• implements
• inherits
• يستورد

Q55. Why are ArrayLists better than arrays?

• You don’t have to decide the size of an ArrayList when you first make it.
• You can put more items into an ArrayList than into an array.
• ArrayLists can hold more kinds of objects than arrays.
• You don’t have to decide the type of an ArrayList when you first make it.

س 56. Declare a variable that holds the first four digits of Π

• int pi = 3.141;
• decimal pi = 3.141;
• double pi = 3.141;
• float pi = 3.141;

Reasoning:

public class TestReal {
    public static void main (String[] argv)
    {
      double pi = 3.14159265;       //accuracy up to 15 digits
      float pi2 = 3.141F;           //accuracy up to 6-7 digits

      System.out.println ("Pi=" + pi);
      System.out.println ("Pi2=" + pi2);
    }
  }

The default Java type which Java will be used for a float variable will be double.
So, even if you declare any variable as float, what the compiler has to do is assign a double value to a float variable,
which is not possible. So, to tell the compiler to treat this value as a float, that 'F' is used.

Q57. Use the magic power to cast a spell

public class MagicPower {
    void castSpell(String spell) {}
}

• new MagicPower().castSpell("expecto patronum");
• MagicPower magicPower = new MagicPower(); magicPower.castSpell();
• MagicPower.castSpell("expelliarmus");
• new MagicPower.castSpell();

مرجع

س 58. What language construct serves as a blueprint containing an object’s properties and functionality?

• البناء
• instance
• صف دراسي
• طريقة

س 59. What does this code print?

public static void main(String[] args) {
    int x=5,y=10;
    swapsies(x,y);
    System.out.println(x+" "+y);
}

static void swapsies(int a, int b) {
    int temp=a;
    a=b;
    b=temp;
}

• 10 10
• 5 10
• 10 5
• 5 5

س 60. What is the result of this code?

try {
    System.out.println("Hello World");
} catch (Exception e) {
    System.out.println("e");
} catch (ArithmeticException e) {
    System.out.println("e");
} finally {
    System.out.println("!");
}

• مرحبا بالعالم
• It will not compile because the second catch statement is unreachable
• مرحبا بالعالم!
• It will throw a runtime exception

س 61. Which is not a Java keyword

• أخيرا
• محلي
• interface
• unsigned

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت: native is a part of the JNI interface.

س 62. Which operator would you use to find the remainder after division?

• %
• //
• /
• DIV

مرجع

س 63. Which choice is a disadvantage of inheritance?

• Overridden methods of the parent class cannot be reused.
• Responsibilities are not evenly distributed between parent and child classes.
• Classes related by inheritance are tightly coupled to each other.
• The internal state of the parent class is accessible to its children.

مرجع

س 64. How would you declare and initialize an array of 10 ints?

• Array<Integer> numbers = new Array<Integer>(10);
• Array[int] numbers = new Array[int](10);
• int[] numbers = new int[10];
• int numbers[] = int[10];

س 65. Refactor this event handler to a lambda expression:

groucyButton.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {
        System.out.println("Press me one more time..");
    }
});

• groucyButton.addActionListener(ActionListener listener -> System.out.println("Press me one more time..."));
• groucyButton.addActionListener((event) -> System.out.println("Press me one more time..."));
• groucyButton.addActionListener(new ActionListener(ActionEvent e) {() -> System.out.println("Press me one more time...");});
• groucyButton.addActionListener(() -> System.out.println("Press me one more time..."));

مرجع

س 66. Which functional interfaces does Java provide to serve as data types for lambda expressions?

• مراقب, Observable
• Collector, Builder
• منقي, خريطة, Reduce
• Consumer, Predicate, Supplier

مرجع

Q67. What is a valid use of the hashCode() طريقة?

• encrypting user passwords
• deciding if two instances of a class are equal
• enabling HashMap to find matches faster
• moving objects from a List to a HashMap

مرجع

Q68. What kind of relationship does “extends” denote?

• uses-a
• is-a
• has-a
• was-a

مرجع

Q69. How do you force an object to be garbage collected?

• Set object to null and call Runtime.gc()
• Set object to null and call System.gc()
• Set object to null and call Runtime.getRuntime().runFinalization()
• There is no way to force an object to be garbage-collected

مرجع

س 70. Java programmers commonly use design patterns. Some examples are the _, which helps create instances of a class, ال _, which ensures that only one instance of a class can be created; و ال _, which allows for a group of algorithms to be interchangeable.

• static factory method; singleton; strategy pattern
• strategy pattern; static factory method; singleton
• creation pattern; singleton; prototype pattern
• singleton; strategy pattern; static factory method

س 71. Using Java’s Reflection API, you can use _ to get the name of a class and _ to retrieve an array of its methods.

• this.getClass().getSimpleName(); this.getClass().getDeclaredMethods()
• this.getName(); this.getMethods()
• Reflection.getName(هذه); Reflection.getMethods(هذه)
• Reflection.getClass(هذه).getName(); Reflection.getClass(هذه).getMethods()

التحكم في مخاطر سلامة العمليات. Which is not a valid lambda expression?

• a -> false;
• (a) -> false;
• String a -> false;
• (String a) -> false;

Q73. Which access modifier makes variables and methods visible only in the class where they are declared?

• عامة
• محمي
• nonmodifier
• خاص

التحكم في مخاطر سلامة العمليات. What type of variable can be assigned only once?

• خاص
• non-static
• نهائي
• static

Q75. How would you convert a String to an Int?

• "21".intValue()
• String.toInt("21")
• Integer.parseInt("21")
• String.valueOf("21")

س 76. What method should be added to the Duck class to print the name Moby?

public class Duck {
    private String name;

    Duck(String name) {
        this.name = name;
    }

    public static void main(String[] args) {
        System.out.println(new Duck("Moby"));
    }
}

• public String toString() { return name; }
• public void println() { System.out.println(name); }
• String toString() { return this.name; }
• public void toString() { System.out.println(this.name); }

Q77. Which operator is used to concatenate Strings in Java

• +
• &
• .
• -

مرجع

Q78. How many times does this loop print “exterminate”?

for (int i = 44; i > 40; i--) {
    System.out.println("exterminate");
}

• اثنان
• أربعة
• ثلاثة
• five

Q79. What is the value of myCharacter after line 3 is run?

public class Main {
  public static void main (String[] args) {
    char myCharacter = "piper".charAt(3);
  }
}

• ص
• ص
• البريد
• أنا

س 80. When should you use a static method?

• when your method is related to the object’s characteristics
• when you want your method to be available independently of class instances
• when your method uses an object’s instance variable
• when your method is dependent on the specific instance that calls it

س 81. What phrase indicates that a function receives a copy of each argument passed to it rather than a reference to the objects themselves?

• pass by reference
• pass by occurrence
• pass by value
• API call

س 82. In Java, what is the scope of a method’s argument or parameter?

• inside the method
• both inside and outside the method
• neither inside nor outside the method
• outside the method

س 83. ما هو الناتج من هذا الكود?

public class Main {
  public static void main (String[] args) {
    int[] sampleNumbers = {8, 5, 3, 1};
    System.out.println(sampleNumbers[2]);
  }
}

• 5
• 8
• 1
• 3

س 84. Which change will make this code compile successfully?

public class Main {
  String MESSAGE ="Hello!";
  static void print(){
    System.out.println(message);
  }
  void print2(){}
}

• Change line 2 إلى public static final String message
• Change line 6 إلى public void print2(){}
• Remove the body of the print2 method and add a semicolon.
• Remove the body of the print طريقة.

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت: Changing line 2 إلى public static final String message raises the error message not initialized in the default constructor.

Q85. ما هو الناتج من هذا الكود?

import java.util.*;
class Main {
  public static void main(String[] args) {
    String[] array = new String[]{"A", "B", "C"};
    List<String> list1 = Arrays.asList(array);
    List<String> list2 = new ArrayList<>(Arrays.asList(array));
    List<String> list3 = new ArrayList<>(Arrays.asList("A", new String("B"), "C"));
    System.out.print(list1.equals(list2));
    System.out.print(list1.equals(list3));
  }
}

• falsefalse
• truetrue
• falsetrue
• truefalse

س 86. Which code snippet is valid?

• ArrayList<String> words = new ArrayList<String>(){"Hello", "World"};
• ArrayList words = Arrays.asList("Hello", "World");
• ArrayList<String> words = {"Hello", "World"};
• ArrayList<String> words = new ArrayList<>(Arrays.asList("Hello", "World"));

Q87. ما هو الناتج من هذا الكود?

class Main {
  public static void main(String[] args) {
    StringBuilder sb = new StringBuilder("hello");
    sb.deleteCharAt(0).insert(0, "H").append(" World!");
    System.out.println(sb);
  }
}

• It will not compile.
• “مرحبا بالعالم!”
• “مرحبًا”
• ???? The code effectively converts the initial “مرحبًا” إلى “HelloWorld!” by deleting the first character, inserting “H” في البداية, and appending ” World!” to the end.

Q88. How would you use the TaxCalculator to determine the amount of tax on $50?

class TaxCalculator {
  static calculate(total) {
    return total * .05;
  }
}

• TaxCalculator.calculate(50);
• new TaxCalculator.calculate(50);
• حساب(50);
• new TaxCalculator.calculate($50);

ملحوظة: This code won’t compile, broken code sample.

1. مرجع
2. Code sample

Q89. Which characteristic does not apply to instances of java.util.HashSet?

• uses hashcode of objects when inserted
• contains unordred elements
• contains unique elements
• contains sorted elements

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت: HashSet makes no guarantees as to the iteration order of the set; خاصه, it does not guarantee that the order will remain constant over time.

مرجع

س 90. What is the output?

import java.util.*;

public class Main {
    public static void main(String[] args)
    {
        PriorityQueue<Integer> queue = new PriorityQueue<>();
        queue.add(4);
        queue.add(3);
        queue.add(2);
        queue.add(1);

        while (queue.isEmpty() == false) {
            System.out.printf("%d", queue.remove());
        }
    }
}

• 1 3 2 4
• 4 2 3 1
• 1 2 3 4
• 4 3 2 1

س 91. What will this code print, assuming it is inside the main method of a class?

System.out.println("hello my friends".split(" ")[0]);

• الحرية والسعادة ... أعطيتها كل ما لدي "
• hellomyfriends
• مرحبًا
• أصدقاء

Q92. You have an instance of type Map<String, Integer> named instruments containing the following key-value pairs: guitar=1200, cello=3000, and drum=2000. If you add the new key-value pair cello=4500 to the Map using the put method, how many elements do you have in the Map when you call instruments.size()?

• 2
• When calling the put method, Java will throw an exception
• 4
• 3

Q93. Which class acts as the root class for the Java Exception hierarchy?

• Clonable
• Throwable
• Object
• Serializable

Q94. Which class does not implement the java.util.Collection interface?

• java.util.Vector
• java.util.ArrayList
• java.util.HashSet
• java.util.HashMap

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت: HashMap class implements Map interface.

س 95. You have a variable of named employees of type List<Employee> containing multiple entries. ال Employee type has a method getName() that returns the employee name. Which statement properly extracts a list of employee names?

• employees.collect(employee -> employee.getName());
• employees.filter(Employee::getName).collect(Collectors.toUnmodifiableList());
• employees.stream().map(Employee::getName).collect(Collectors.toList());
• employees.stream().collect((e) -> e.getName());

Q96. This code does not compile. What needs to be changed so that it does?

public enum Direction {
    EAST("E"),
    WEST("W"),
    NORTH("N"),
    SOUTH("S");

    private final String shortCode;

    public String getShortCode() {
        return shortCode;
    }
}

• Add a constructor that accepts a String parameter and assigns it to the field shortCode.
• Remove the final keyword for the field shortCode.
• All enums need to be defined on a single line of code.
• Add a setter method for the field shortCode.

Q97. Which language feature ensures that objects implementing the AutoCloseable interface are closed when it completes?

• try-catch-finally
• try-finally-close
• try-with-resources
• try-catch-close

Q98. What code should go in line 3?

class Main {
    public static void main(String[] args) {
        array[0] = new int[]{1, 2, 3};
        array[1] = new int[]{4, 5, 6};
        array[2] = new int[]{7, 8, 9};
        for (int i = 0; i < 3; i++)
            System.out.print(array[i][1]); //prints 258
    }
 }

• int[][] array = new int[][];
• int[][] array = new int[3][3];
• int[][] array = new int[2][2];
• int[][] array = [][];

Q99. Is this an example of method overloading or overriding?

class Car {
    public void accelerate() {}
}
class Lambo extends Car {
    public void accelerate(int speedLimit) {}
    public void accelerate() {}
}

• neither
• على حد سواء
• overloading
• overriding

س100. Which choice is the best data type for working with money in Java?

• float
• String
• مزدوج
• BigDecimal

مرجع

س101. Which statement about constructors is not true?

• A class can have multiple constructors with a different parameter list.
• You can call another constructor with this أو super.
• A constructor does not define a return value.
• Every class must explicitly define a constructor without parameters.

س102. What language feature allows types to be parameters on classes, واجهات, and methods in order to reuse the same code for different data types?

• Regular Expressions
• انعكاس
• Generics
• Concurrency

Q103. What will be printed?

public class Berries{

    String berry = "blue";

    public static void main(String[] args) {
        new Berries().juicy("straw");
    }
    void juicy(String berry){
        this.berry = "rasp";
        System.out.println(berry + "berry");
    }
}

• توت العليق
• الفراولة
• blueberry
• rasp

س104. What is the value of forestCount after this code executes?

Map<String, Integer> forestSpecies = new HashMap<>();

forestSpecies.put("Amazon", 30000);
forestSpecies.put("Congo", 10000);
forestSpecies.put("Daintree", 15000);
forestSpecies.put("Amazon", 40000);

int forestCount = forestSpecies.size();

• 3
• 4
• 2
• When calling the put method, Java will throw an exception

س105. What is the problem with this code?

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;


class Main {

    public static void main(String[] args) {
        List<String> list = new ArrayList<String>(Arrays.asList("a", "b", "c"));
        for(String value :list) {
            if(value.equals("a")) {
                list.remove(value);
            }
        }
        System.out.println(list); // outputs [b,c]
    }
}

• String should be compared using == method instead of equals.
• Modifying a collection while iterating through it can throw a ConcurrentModificationException.
• The List interface does not allow an argument of type String to be passed to the remove method.
• ArrayList does not implement the List interface.

س106. How do you convert this method into a lambda expression?

public int square(int x) {
    return x * x;
}

• Function<Integer, Integer> squareLambda = (int x) -> { x * x };
• Function<Integer, Integer> squareLambda = () -> { return x * x };
• Function<Integer, Integer> squareLambda = x -> x * x;
• Function<Integer, Integer> squareLambda = x -> return x * x;

Q107. Which choice is a valid implementation of this interface?

interface MyInterface {
    int foo(int x);
}

• ا

public class MyClass implements MyInterface {
    // ....
    public void foo(int x){
        System.out.println(x);
    }
}

• ب

public class MyClass implements MyInterface {
    // ....
    public double foo(int x){
        return x * 100;
    }
}

• C

public class MyClass implements MyInterface {
    // ....
    public int foo(int x){
        return x * 100;
    }
}

• د

public class MyClass implements MyInterface {
    // ....
    public int foo(){
        return 100;
    }
}

س 108. What is the result of this program?

interface Foo {
    int x = 10;
}

public class Main{

    public static void main(String[] args) {
        Foo.x = 20;
        System.out.println(Foo.x);
    }
}

• 10
• 20
• باطل
• An error will occur when compiling.

س 109. Which statement must be inserted on line 1 to print the value true?

1:
2: Optional<String> opt = Optional.of(val);
3: System.out.println(opt.isPresent());

• Integer val = 15;
• String val = "Sam";
• String val = null;
• Optional<String> val = Optional.empty();

س 110. What will this code print, assuming it is inside the main method of a class?

System.out.println(true && false || true);
System.out.println(false || false && true);

• خاطئة
  صحيح
• صحيح
  صحيح
• صحيح
  خاطئة
• خاطئة
  خاطئة

س111. What will this code print?

List<String> list1 = new ArrayList<>();
list1.add("One");
list1.add("Two");
list1.add("Three");

List<String> list2 = new ArrayList<>();
list2.add("Two");

list1.remove(list2);
System.out.println(list1);

• [Two]
• [One, Two, Three]
• [One, Three]
• Two

س112. Which code checks whether the characters in two Strings,اسم الشيئ time و money, are the same?

• if(time <> money){}
• if(time.equals(money)){}
• if(time == money){}
• if(time = money){}

يتم تحديد حدود العملية من خلال تعيين المستويات العليا والسفلى لمجموعة من المعلمات. ل _ is a serious issue thrown by the JVM that the JVM is unlikely to recover from. ل _ is an unexpected event that an application may be able to deal with to continue execution.

• exception,assertion
• AbnormalException, AccidentalException
• خطأ, exception
• exception, خطأ

س114. Which keyword would not be allowed here?

class Unicorn {
    _____ Unicorn(){}
}

• static
• محمي
• عامة
• void

س115. Which OOP concept is this code an example of?

List[] myLists = {
    new ArrayList<>(),
    new LinkedList<>(),
    new Stack<>(),
    new Vector<>(),
};

for (List list : myLists){
    list.clear();
}

• تكوين
• generics
• polymorphism
• encapsulation

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت: Switch between different implementations of the List interface.

س116. What does this code print?

String a = "bikini";
String b = new String("bikini");
String c = new String("bikini");

System.out.println(a == b);
System.out.println(b == c);

• صحيح; خاطئة
• خاطئة; خاطئة
• خاطئة; صحيح
• صحيح; صحيح

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت: == operator compares the object reference. String a = "bikini"; String b = "bikini"; would result in True. Here new creates a new object, so false. استعمال equals() method to compare the content.

س117. What keyword is added to a method declaration to ensure that two threads do not simultaneously execute it on the same object instance?

• محلي
• متطايره
• synchronized
• lock

مرجع

س 118. Which is a valid type for this lambda function?

_____ oddOrEven = x -> {
    return x % 2 == 0 ? "even" : "odd";
};

• Function<Integer, Boolean>
• Function<String>
• Function<Integer, String>
• Function<Integer>

Explaination, مرجع

Q119. What is displayed when this code is compiled and executed?

import java.util.HashMap;

public class Main {
    public static void main(String[] args) {
        HashMap<String, Integer> pantry = new HashMap<>();

        pantry.put("Apples", 3);
        pantry.put("Oranges", 2);

        int currentApples = pantry.get("Apples");
        pantry.put("Apples", currentApples + 4);

        System.out.println(pantry.get("Apples"));
    }
}

• 6
• 3
• 4
• 7

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت

يتم تحديد حدود العملية من خلال تعيين المستويات العليا والسفلى لمجموعة من المعلمات. What variable type should be declared for capitalization?

List<String> songTitles = Arrays.asList("humble", "element", "dna");
_______ capitalize = (str) -> str.toUpperCase();
songTitles.stream().map(capitalize).forEach(System.out::println);

• Function<String, String>
• Stream<String>
• String<String, String>
• Map<String, String>

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت, مرجع

س 121. Which is the correct return type for the processFunction method?

_____ processFunction(Integer number, Function<Integer, String> lambda) {
    return lambda.apply(number);
}

• Integer
• String
• Consumer
• Function<Integer, String>

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت

Q122. What function could you use to replace slashes for dashes in a list of dates?

List<String> dates = new ArrayList<String>();
// missing code
dates.replaceAll(replaceSlashes);

• UnaryOperator<String> replaceSlashes = date -> date.replace("/", "-");
• Function<String, String> replaceSlashes = dates -> dates.replace("-", "/");
• Map<String, String> replaceSlashes = dates.replace("/", "-");
• Consumer<Date> replaceSlashes = date -> date.replace("/", "-");

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت: replaceAll method for any List only accepts UnaryOperator to pass every single element into it then put the result into the List again.

Q123. From which class do all other classes implicitly extend?

• Object
• Main
• Java
• Class

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت

س 124. How do you create and run a Thread for this class?

import java.util.date;

public class CurrentDateRunnable implements Runnable {
    @Override
    public void run () {
        while (true) {
            System.out.println("Current date: " + new Date());

            try {
                Thread.sleep(5000);
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        }
    }
}

• Thread thread = new Thread(new CurrentDateRunnable()); thread.start();
• new Thread(new CurrentDateRunnable()).join();
• new CurrentDateRunnable().run();
• new CurrentDateRunnable().start();

مرجع

Q125. Which expression is a functional equivalent?

List<Integer> numbers = List.of(1,2,3,4);
int total = 0;

for (Integer x : numbers) {
    if (x % 2 == 0)
    total += x * x;
}

• ا

int total = numbers.stream()
                        .transform(x -> x * x)
                        .filter(x -> x % 2 == 0)
                        .sum ();

• ب

int total = numbers.stream()
                        .filter(x -> x % 2 == 0)
                        .collect(Collectors.toInt());

• C

int total = numbers.stream()
                        .mapToInt (x -> {if (x % 2 == 0) return x * x;})
                        .sum();

• د

int total = numbers.stream()
                        .filter(x -> x % 2 == 0)
                        .mapToInt(x -> x * x)
                        .sum();

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت: The given code in the question will give you the output 20 as total:

numbers                         // Input `List<Integer>` > [1, 2, 3, 4]
    .stream()                   // Converts input into `Stream<Integer>`
    .filter(x -> x % 2 == 0)    // Filter even numbers and return `Stream<Integer>` > [2, 4]
    .mapToInt(x -> x * x)       // Square the number, converts `Integer` to an `int`, and returns `IntStream` > [4, 16]
    .sum()                      // Returns the sum as `int` > 20

س126. Which is not one of the standard input/output streams provided by java.lang.System?

• أعمال التصميم الجرافيكي والمواد التسويقية
• out
• err
• في

مرجع

Q127. The compiler is complaining about this assignment of the variable pickle to the variable jar. How would you fix this?

double pickle = 2;
int jar = pickle;

• Use the method toInt() to convert the pickle before assigning it to the jar.
• Cast pickle to an int before assigning it to the jar.
• Make pickle into a double by adding + “.0”
• Use the new keyword to create a new Integer from pickle before assigning it to the jar.

مرجع

Q128. What value should x have to make this loop execute 10 مرات?

for(int i=0; i<30; i+=x) {}

• 10
• 3
• 1
• 0

Q129. ال _ runs compiled Java code, بينما ال _ compiles Java files.

• نظام الري الذكي; JRE
• JDK; نظام الري الذكي
• JRE; JDK
• JDK; JRE

مرجع

س130. Which packages are part of Java Standard Edition

• java.net
• java.util
• java.lang
• All above

مرجع

Q131. What values for x and y will cause this code to print “btc”?

String buy = "bitcoin";
System.out.println(buy.substring(x, x+1) + buy.substring(y, y+2))

• int x = 0; int y = 2;
• int x = 1; int y = 3;
• int x = 0; int y = 3;
• int x = 1; int y = 3;

Q132. Which keyword would you add to make this method the entry point of the program?

public class Main {
    public static void main(String[] args) {
        // Your program logic here
    }
}

• exception
• args
• static
• String

مرجع To make the main method the entry point of the program in Java, we need to use the static keyword. وبالتالي, the correct answer is: static The main method must be declared as public static void main(String[] args) to serve as the entry point for a Java program

Q133. You have a list of Bunny objects that you want to sort by weight using Collections.sort. What modification would you make to the Bunny class?

//This is how the original bunny class looks
class Bunny{
    String name;
    int weight;

    Bunny(String name){
        this.name = name;
    }
    public static void main(String args[]){
        Bunny bunny = new Bunny("Bunny 1");
    }
}

• Implement the Comparable interface by overriding the compareTo method.
• Add the keyword default to the weight variable.
• Override the equals method inside the Bunny class.
• Implement Sortable and override the sortBy method.

مرجع

س 134. Identify the incorrect Java feature.

• Object-oriented
• Use of pointers
• متحرك
• Architectural neural

مرجع

Q135. ما هو الناتج من هذا الكود?

int yearsMarried = 2;
switch (yearsMarried) {
   case 1:
      System.out.println("paper");
   case 2:
      System.out.println("cotton");
   case 3:
      System.out.println("leather");
   default:
      System.out.println("I don't gotta buy gifts for nobody!");
}

• قطن
• قطن
  leather
• قطن
  leather
  I don’t gotta buy gifts for nobody!
• قطن
  I don’t gotta buy gifts for nobody!

مرجع

س 136. What language features do these expressions demonstrate?

System.out::println
Doggie::fetch

• condensed invocation
• static references
• method references
• bad code

مرجع

Q137. What is the difference between the wait() and sleep() أساليب?

• Only Threads can wait, but any Object can be put to sleep.
• A waiter can be woken up by another Thread calling notification whereas a sleeper cannot.
• When things go wrong, sleep throws an IllegalMonitorStateException whereas wait throws an InterruptedException.
• Sleep allows for multi-threading whereas wait does not.

مرجع

Q138. Which is the right way to declare an enumeration of cats?

• enum Cats (SPHYNX, SIAMESE, BENGAL);
• enum Cats (“sphynx”, “siamese”, “bengal”);
• enum Cats {SPHYNX, SIAMESE, BENGAL}
• enum Cats {“sphynx”,”siamese”,”bengal}

Q139. What happens when this code is run?

List<String> horses = new ArrayList<String>();
horses.add (" Sea Biscuit ");
System.out.println(horses.get(1).trim());

• “Sea Biscuit” will be printed.
• ” Sea Biscuit ” will be printed.
• An IndexOutOfBoundsException will be thrown.
• A NullPointerException will be thrown.

س 140. Which data structure would you choose to associate the amount of rainfall with each month?

• المتجه
• LinkedList
• خريطة
• طابور

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت:

from @yktsang01 in #3915 thread

Map because the map is a key/value pair without creating new classes/objects. So can store the rainfall per month like Map<java.time.Month, Double>. The other options will most likely need some new class to be meaningful:

public class Rainfall {
    private java.time.Month month;
    private double rainfall;
}
Vector<Rainfall>
LinkedList<Rainfall>
Queue<Rainfall>

س 141. Among the following which contains date information?

• java.sql timestamp
• java.io time
• java.io.timestamp
• java.sql.time

س 142. What is the size of float and double in Java?

• 32 و 64
• 32 و 32
• 64 و 64
• 64 و 32

Q143. When you pass an object reference as an argument to a method call what gets passed?

• a reference to a copy
• a copy of the reference
• the object itself
• the original reference

س144. Which choice demonstrates a valid way to create a reference to a static function of another class?

• وظيفة<Integer, Integer> funcReference = MyClass::myFunction;
• وظيفة<Integer, Integer> funcReference = MyClass()::myFunction();
• وظيفة<Integer, Integer> funcReference = MyClass().myFunction;
• وظيفة<Integer, Integer> funcReference = MyClass.myFunction();

س145. What is UNICODE?

• Unicode is used for the external representation of words and strings
• Unicode is used for internal representation of characters and strings
• Unicode is used for external representation of characters and strings
• Unicode is used for the internal representation of words and strings

س146. What kind of thread is the Garbage collector thread?

• User thread
• Daemon thread
• Both
• None of these

Q147. What is HashMap and Map?

• HashMap is Interface and map is a class that implements that
• HashMap is a class and map is an interface that implements that
• Map is a class and Hashmap is an interface that implements that
• Map is Interface and Hashmap is the class that implements that

س148. What invokes a thread’s run() طريقة?

• JVM invokes the thread’s run() method when the thread is initially executed.
• Main application running the thread.
• بداية() method of the thread class.
• لا شيء مما بالأعلى.

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت: After a thread is started, via its start() method of the Thread class, the JVM invokes the thread’s run() method when the thread is initially executed.

Q149. What is true about a final class?

• class declared final is a final class.
• Final classes are created so the methods implemented by that class cannot be overridden.
• It can’t be inherited.
• كل ما ورداعلاه.

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت: Final classes are created so the methods implemented by that class cannot be overridden. It can’t be inherited. These classes are declared final.

س150. Which method can be used to find the highest value of x and y?

• Math.largest(س,و)
• Math.maxNum(س,و)
• Math.max(س,و)
• Math.maximum(س,و)

س151. void accept(T t) is method of which Java functional interface?

• Consumer
• منتج
• Both
• لا شيء

س152. Which of these does Stream filter() operate on?

• Predicate
• واجهه المستخدم
• Class
• أساليب

Q153. Which of these does Stream map() operates on?

• Class
• واجهه المستخدم
• Predicate
• وظيفة

س154. What code is needed at line 8?

1: class Main {
2:      public static void main(String[] args) {
3:          Map<String, Integer> map = new HashMap<>();
4:          map.put("a", 1);
5:          map.put("b", 2);
6:          map.put("c", 3);
7:          int result = 0;
8:
9:              result += entry.getValue();
10:         }
11:         System.out.println(result); // outputs 6
12:     }
13: }

• إلى عن على(MapEntry<String, Integer> ■ اللاتينية و / أو اليونانية: map.entrySet()) {
• إلى عن على(String entry: خريطة) {
• إلى عن على(Integer entry: map.values()) {
• إلى عن على(دخول<String, Integer> ■ اللاتينية و / أو اليونانية: map.entrySet()) {

Q155. What will print when Lambo is instantiated?

class Car {
    String color = "blue";
}

class Lambo extends Car {
    String color = "white";

    public Lambo() {
        System.out.println(super.color);
        System.out.println(this.color);
        System.out.println(color);
    }
}

• blue white white
• blue white blue
• white white white
• white white blue

Q156. Which command will run a FrogSounds app that someone emailed to you as a jar?

• jar FrogSounds.java
• javac FrogSounds.exe
• jar cf FrogSounds.jar
• java -jar FrogSounds.jar

Q157. What is the default value of a short variable?

• 0
• 0.0
• باطل
• غير معرف

Q158. What will be the output of the following Java program?

class variable_scope {
    public static void main(String args[]) {
        int x;
        x = 5;
        {
            int y = 6;
            System.out.print(x + " " + y);
        }
        System.out.println(x + " " + y);
    }
}

• Compilation Error
• Runtime Error
• 5 6 5 6
• 5 6 5

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت: Scope of variable Y is limited.

Q159. Subclasses of an abstract class are created using the keyword _.

• extends
• abstracts
• واجهات
• implements

مرجع

س160. What will be the output of the following program?

import java.util.Formatter;
public class Course {
    public static void main(String[] args) {
        Formatter data = new Formatter();
        data.format("course %s", "java ");
        System.out.println(data);
        data.format("tutorial %s", "Merit campus");
        System.out.println(data);
    }
}

• course java tutorial Merit campus
• course java course java tutorial Merit campus
• Compilation Error
• Runtime Error

س161. Calculate the time complexity of the following program.

 void printUnorderedPairs(int[] arrayA, int[] arrayB){
    for(int i = 0; i < arrayA.length; i++){
        for(int  j = 0; j < arrayB.length; j++){
            if(arrayA[i] < arrayB[j]){
                System.out.println(arrayA[i] + "," + arrayB[j]);
            }
        }
    }
 }

• ال(N*N)
• ال(1)
• ال(من عند)
• ال(A*B)

Q162. What do these expressions evaluate?

1. true && false
2. true && false || true

• 1. خاطئة 2. صحيح
• 1. خاطئة 2. خاطئة
• 1. صحيح 2. خاطئة
• 1. صحيح 2. صحيح

مرجع //check page number 47 and example number 4.:-}

Q163. What allows the programmer to destroy an object x?

• 1. x.delete()
• 2. x.finalize()
• 3. Runtime.getRuntime().gc()
• 4. Only the garbage collection system can destroy an object.

مرجع //لا, the Garbage Collection can not be forced explicitly. We may request JVM for garbage collection by calling System.gc() طريقة. But This does not guarantee that JVM will perform the garbage collection

س164. How many objects are eligible for garbage collection till flag

public class Test
{
    public static void main(String [] args)
    {
        Test obj1 = new Test();
        Test obj2 = m1(obj1);
        Test obj4 = new Test();
        obj2 = obj4;               //Flag
        doComplexStuff();
    }
    static Test m1(Test mx)
    {
        mx = new Test();
        return mx;
    }
}

• 1. 0
• 2. 1
• 3. 2
• 4. 4

مرجع // question no 5.

Q165. Which interface definition allows this code to compile

int length = 5;
Square square = x -> x*x;
int a = square.calculate(length);

• ا

@FunctionalInterface
public interface Square {
    void calculate(int x);
}

• ب

@FunctionalInterface
public interface Square {
    int calculate(int x);
}

• C

@FunctionalInterface
public interface Square {
    int calculate(int... x);
}

• د

@FunctionalInterface
public interface Square {
    void calculate(int x, int y);
}

مرجع

Q166. Which of the following represents the time complexity of an algorithm?

• ال(N*N)
• ال(1)
• ال(A+B)
• ال(A*B)

Reasoning: The answer option ‘O(من عند)’ should be corrected to ‘O(A*B)’ to accurately represent the time complexity.

• ال(N*N): This represents a quadratic time complexity, where the running time grows with the square of the input size.
• ال(1): This represents constant time complexity, indicating that the algorithm’s running time doesn’t depend on the input size.
• ال(A+B): This represents linear time complexity, indicating that the running time scales linearly with the sum of values A and B.
• ال(A*B): This represents quadratic time complexity, indicating that the running time scales quadratically with the product of values A and B.

The original answer option 'O(AB)' is incorrect as it does not properly represent a known time complexity notation. The correct notation should be 'O(A*B)' to indicate quadratic time complexity.

مرجع

Q167. Calculate the space complexity of the following program.

void createArray(int n) {
    int[] arr = new int[n];
    for (int i = 0; i < n; i++) {
        arr[i] = i * 2;
    }
}

• ال(1)
• ال(N)
• ال(N^2)
• ال(log(N))

//في هذا البرنامج, an array of size n is created. The space complexity is determined by the size of the dynamic array, which is n. وبالتالي, the space complexity is O(N).

Q167. What will be the output of the following Java code?

    import java.util.*;
    public class genericstack <E>
    {
        Stack <E> stk = new Stack <E>();
    public void push(E obj)
        {
            stk.push(obj);
    }
    public E pop()
        {
            E obj = stk.pop();
        return obj;
    }
    }
    class Output
    {
        public static void main(String args[])
        {
            genericstack <String> gs = new genericstack<String>();
            gs.push("Hello");
            System.out.println(gs.pop());
        }
    }

• H
• أهلا
• Runtime Error
• Compilation Error

//في هذا البرنامج, The code defines a generic stack class, pushes the string “أهلا” onto the stack, and then pops and prints “أهلا,” resulting in the output “Hello.”

Q168. In Java, what is the purpose of the synchronized keyword when used in the context of methods or code blocks?

• It is used to specify that a method or code block is asynchronous, allowing multiple threads to execute it concurrently.
• It is used to mark a method or code block as thread-safe, ensuring that only one thread can execute it at a time.
• It indicates that the method or code block is highly optimized for performance and will run faster than non-synchronized methods.
• It is used to prevent a method or code block from being executed by any thread, making it effectively “locked.”

Q169. In Java, which of the following statements about the “transient” modifier is true?

• Transient variables cannot be accessed outside their declaring class.
• Transient variables are automatically initialized with a default value.
• Transient variables are not serialized when an object is serialized.
• Transient is a keyword used to define inner classes.

Q170. The following prototype shows that a Cylinder subclass is derived from a superclass called Circle.

• Class Circle extends Cylinder.
• Class Cylinder derived Circle.
• Class Cylinder extends Circle.
• Class Circle derived Cylinder.

Q171. What will be the output of the following Java code snippet?

class abc
{
    public static void main(String args[])
    {
        if(args.length>0)
        System.out.println(args.length);
    }
}

• The snippet compiles and runs but does not print anything.
• The snippet compiles, أشواط, and prints 0.
• The snippet compiles, أشواط, and prints 1.
• The snippet does not compile.

Q172. Which of these classes allows us to define our own formatting pattern for dates and times?

• DefinedDateFormat
• SimpleDateFormat
• ComplexDateFormat
• UsersDateFormatRead

مرجع

Q173.What kind of relationship does extends denote?

• is-a
• has-a
• was-a
• uses-a