Java Quiz

Question 21.

         Read this piece of code carefully

if("String".substring(0) == "String")
    System.out.println("Equal");
else
    System.out.println("Not Equal");

Answers

1. the code will compile an print "Equal".
2. the code will compile an print "Not Equal".
3. the code will cause a compiler error

Question 22.

         Read this piece of code carefully

if("String".substring(0,6) == "String")
    System.out.println("Equal");
else
    System.out.println("Not Equal");

Answers

1. the code will compile an print "Equal".
2. the code will compile an print "Not Equal".
3. the code will cause a compiler error

Question 23.

         Read this piece of code carefully

if("String".replace('t','t') == "String")
    System.out.println("Equal");
else
    System.out.println("Not Equal");

Answers

1. the code will compile an print "Equal".
2. the code will compile an print "Not Equal".
3. the code will cause a compiler error

Question 24.

         An Anonymous Inner class
 

1.  Does not have a constructor
2.  Can implement an interface
3.  Can extend a non-final Class
4.  Can implement an interface and extend a non-final class (at the same time).

Question 25.
 

public class A
{

 private void method1() throws Exception
 {
      throw new RuntimeException();
 }

 public void method2()
 {
     try
     {
       method1();
     }
     catch(RuntimeException e)
     {
          System.out.println("Caught Runtime Exception");
     }
     catch(Exception e)
     {
          System.out.println("Caught Exception");
     }
 }

 public static void main(String args[])
 {
      A a = new A();
      a.method2();
 }

}

1.  will not compile.
2.  will compile and show - "Caught Runtime Exception".
3.  will compile and show - "Caught Exception".
4.  will compile and show both the messages one after another in the order they appear.

Question 26.

     public XXXX extends something1, something2
 

1. XXX should be an interface,something1 and something2 need not, for the expression to be legal
2. XXX should be a class, something1 and something2 must be interfaces for the expression to be legal.
3. XXX, something1 and something2 must be interfaces for the expression to be legal.
4. The above statement is alway illegal in Java as multiple inheritance is not supported.

Question 27.

 public class ADirtyOne
 {
      char a = '\u000A';
 }

1.  will complete successfully.
2.  will not compile as 0x000A is out of range for unicode charaters.
3.  will complain about illegal character assignment
4.  will compile but will cause a runtime error in accessing the variable.

 public class ADirtyOne
 {
      //char a = '\u000A';
 }

1.  will complete successfully.
2.  will compile sucessfully  but with a warning message.
3.  will  not compile - complains on an invalid expression.

Question 29.
 

  public class AnotherDirtyOne
 {
      private final int i =10;
      private byte k = i;
 }

An attempt to compile and run the above code will

1. Cause a compilation error  due to invalid assignment ( int to byte) and will request for an explicit cast to be done on i [ k=(byte) i ].
2. Compilation occurs with a warning message - suggesting that the accuracy of k is questionable
3. Compilation will occur cleanly without any warning message.
4. Runtime error occurs when accessing k.

Question 30.

 interface One
 {
      public void someMethod();
 }

 public class One_impl implements One
 {
      public native void someMethod();
 }

 Assuming that the native method is not provided in any local library, an attempt to compile and run the above lines of code will cause
 

1. Compilation error - implimentations can never be native.
2. Compilation error - method not found in local libraries.
3. Runtime Exception - method not found in local libraries.
4. Compilation successfull but runtime error is thrown if and only if the method someMethod of class One_impl is called.