JAVA INTERFACES AND ABSTRACT CLASSES QUIZ

interface Test{ int p = 10; //line 1 public int q = 20; //line 2 public static int r = 30; //line 3 public static final int s = 40; //line 4}Which of the above line will give compilation error?

3

1

2

4

None of these

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What will be the output?interface A{public void method();}class One{public void method(){System.out.println("Class One method");}}class Two extends One implements A{public void method(){System.out.println("Class Two method");}}public class Test extends Two{public static void main(String[] args){A a = new Two();a.method();}}

will print Class Two method

compiles fine but print nothing

None of these

Compilation Error

will print Class One method

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What will happen after compiling this program code?abstract class MyClass{ //line 1 private int a, b; public void call(int a, int b){ this.a = a; this.b = b; System.out.print(a+b); }}public class Test{ public static void main(String args[]){ MyClass m = new MyClass(); //line 2 m.call(12,25); }}

Compilation error due to line 2

Successful run and print 37

Compilation error due to line 1

Runtime error

None of these

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Which of the following statements regarding abstract classes are true?

All of these

An abstract class can be used as a data type.

An abstract class can be extended.

A subclass can override a concrete method in a superclass to declare it abstract.

A subclass of a non-abstract superclass can be abstract.

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What happens if the following program is compiled and executed?interface MyInterface{ void display();}interface MySubInterface extends MyInterface{ void display();}public class Test implements MySubInterface{ public void display(){ System.out.print("Welcome to Examveda."); } public static void main(String args[]){ Test t = new Test(); t.display(); }}

The code will lead to a compilation error as declaration of the display method has been provided in two interface.

The code will lead to a compilation error due to public modifier while declaring the display method.

The code will lead to a compilation error as the display method is not declared as abstract.

The code will compile and execute successfully showing the output Welcome to Examians.

None of these

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Which of the following class definitions defines a legal abstract class?

class A { abstract void unfinished() { } }

public class abstract A { abstract void unfinished(); }

abstract class A { abstract void unfinished(); }

class A { abstract void unfinished(); }

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Which of the following is a correct interface?

interface A { void print(); }

abstract interface A { abstract void print(); { }}

abstract interface A { print(); }

interface A { void print() { } }

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What will be the output for the below code ?public interface TestInf{ int i =10;}public class Test{ public static void main(String... args){ TestInf.i=12; System.out.println(TestInf.i); }}

Runtime Exception

None of these

10

Compile with error

12

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Which of the following declares an abstract method in an abstract Java class?

public void method() {}

public abstract void method() {}

public abstract method();

public abstract void method();

public void abstract Method();

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Given the following piece of code:public class School{ public abstract double numberOfStudent();}which of the following statements is true?

The keywords public and abstract cannot be used together.

You must add a return statement in method numberOfStudent().

Class School must be defined abstract.

The method numberOfStudent() in class School must have a body.

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