Java Programming · all questions

Interfaces and Abstract Classes
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Q1

What is an interface in Java?

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Q2

In Java, can a class implement multiple interfaces?

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Q3

Which keyword is used to declare an interface in Java?

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Q4

What is the purpose of an abstract class in Java?

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Q5

In Java, can an abstract class be instantiated?

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Q6

What is the purpose of the "implements" keyword in Java?

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Q7

Which of the following can contain both abstract and non-abstract methods?

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Q8

In Java, can an interface have fields (member variables)?

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Q9

What is the purpose of an abstract method in an abstract class or interface?

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Q10

Which keyword is used to define an abstract method in Java?

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Q11

In Java, can an interface have private methods with implementations?

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Q12

What is the result of the following code snippet?

interface MyInterface {
    void myMethod();
}
public class MyClass implements MyInterface {
    public void myMethod() {
        System.out.println("Implementation");
    }
    public static void main(String[] args) {
        MyInterface obj = new MyClass();
        obj.myMethod();
    }
}

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Q13

In Java, can an abstract class extend another class?

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Q14

What is the purpose of the "extends" keyword in Java?

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Q15

In Java, can an interface extend another interface?

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Q16

What is the result of the following code snippet?

abstract class MyAbstract {
    abstract void myMethod();
}
class MyClass extends MyAbstract {
    void myMethod() {
        System.out.println("Implementation");
    }
    public static void main(String[] args) {
        MyAbstract obj = new MyClass();
        obj.myMethod();
    }
}

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Q17

In Java, can an abstract class have non-abstract methods?

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Q18

What is the purpose of the "default" keyword in Java interfaces?

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Q19

What is the result of the following code snippet?

interface MyInterface {
    default void myMethod() {
        System.out.println("Default Implementation");
    }
}
class MyClass implements MyInterface {
    public static void main(String[] args) {
        MyInterface obj = new MyClass();
        obj.myMethod();
    }
}

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Q20

In Java, can a class implement an interface and extend an abstract class simultaneously?

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