250+ TOP MCQs on Generics and Answers

This set of Java Multiple Choice Questions & Answers (MCQs) on “Generics”.

1. 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());

```
        }
```
```
    }
```

a) H
b) Hello
c) Runtime Error
d) Compilation Error

Answer: b
Clarification: None.
Output:

$ javac Output.javac
$ java Output
Hello

2. 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 <Integer> gs = new genericstack<Integer>();

```
            gs.push(36);
```

            System.out.println(gs.pop());

```
        }
```
```
    }
```

a) 0
b) 36
c) Runtime Error
d) Compilation Error

Answer: b
Clarification: None.
Output:

$ javac Output.javac
$ java Output
36

3. 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.print(gs.pop() + " ");

            genericstack <Integer> gs = new genericstack<Integer>();

```
            gs.push(36);
```

            System.out.println(gs.pop());

```
        }
```
```
    }
```

a) Error
b) Hello
c) 36
d) Hello 36

Answer: d
Clarification: None.
Output:

250+ TOP MCQs on Method overriding and Answers

$ javac Output.javac
$ java Output
Hello 36

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

```
    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 <Integer> gs = new genericstack<Integer>();

```
            gs.push(36);
```

            System.out.println(gs.pop());

```
        }
```
```
    }
```

a) H
b) Hello
c) Runtime Error
d) Compilation Error

Answer: d
Clarification: genericstack’s object gs is defined to contain a string parameter but we are sending an integer parameter, which results in compilation error.
Output:

$ javac Output.javac
$ java Output

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

```
    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 <Integer> gs = new genericstack<Integer>();

```
            gs.push(36);
```

            System.out.println(gs.pop());

```
        }
```
```
    }
```

a) H
b) Hello
c) Runtime Error
d) Compilation Error

Answer: d
Clarification: generic stack object gs is defined to contain a string parameter but we are sending an integer parameter, which results in compilation error.
Output:

$ javac Output.javac
$ java Output

6. Which of these Exception handlers cannot be type parameterized?
a) catch
b) throw
c) throws
d) all of the mentioned

Answer: d
Clarification: we cannot Create, Catch, or Throw Objects of Parameterized Types as generic class cannot extend the Throwable class directly or indirectly.

250+ TOP MCQs on Java.lang – System Class Advance and Answers

7. Which of the following cannot be Type parameterized?
a) Overloaded Methods
b) Generic methods
c) Class methods
d) Overriding methods

Answer: a
Clarification: Cannot Overload a Method Where the Formal Parameter Types of Each Overload Erase to the Same Raw Type.

contest