Interfaces and Abstract Classes -Java Programming MCQ Questions and Answers

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41. 
interface Base{
      boolean m1 ();
      byte m2(short s);
}

which two code fragments will compile?
1. interface Base2 implements Base {}

2. abstract class Class2 extends Base
    { public boolean m1(){ return true; }}

3. abstract class Class2 implements Base {}

4. abstract class Class2 implements Base
    { public boolean m1(){ return (7 > 4); }}

5. abstract class Class2 implements Base
    { protected boolean m1(){ return (5 > 7) }}

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42.
Which two of the following are legal declarations for abstract classes and interfaces?
1. final abstract class Test {}
2. public static interface Test {}
3. final public class Test {}
4. protected abstract class Test {}
5. protected interface Test {}
6. abstract public class Test {}

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43. 
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?

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44.
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);
      }
}

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46.
What is the output for the below code?
interface A{
      public void printValue();
}

public class Test{
      public static void main (String[] args){
            A a1 = new A(){
                         public void printValue(){
                               System.out.println("A");
                         }
                   };
            a1.printValue();
      }
}

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47.
What will be the output?
public interface InfA{
      protected String getName();
}

public class Test implements InfA{
      public String getName(){
            return "test-name";
      }
      public static void main (String[] args){
            Test t = new Test();
            System.out.println(t.getName());
      }
}

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48.
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);
      }
}

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49.
What will be the output when the following program is compiled and executed?
abstract class TestAbstract{
      String my_name;
      String myName(){
            my_name = "Examveda";
            return my_name;
      }
      abstract void display();
}

public class Test extends TestAbstract{
      void display(){
            String n = myName();
	    System.out.print("My name is "+ n);
      }

      public static void main(String args[]){
            Test t = new Test();
	    t.display();
      }
}

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50.
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();
      }
}

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