Java.lang Class

Practice Java.lang Class –

Which two statements are true about wrapper or String classes?

1. If x and y refer to instances of different wrapper classes, then the fragment x.equals(y) will cause a compiler failure.
2. If x and y refer to instances of different wrapper classes, then x == y can sometimes be true.
3. If x and y are String references and if x.equals(y) is true, then x == y is true.
4. If x, y, and z refer to instances of wrapper classes and x.equals(y) is true, and y.equals(z) is true, then z.equals(x) will always be true.
5. If x and y are String references and x == y is true, then y.equals(x) will be true.

Practice Java.lang Class –

What will be the output of the program (in jdk1.6 or above)?

public class BoolTest {    

  public static void main(String [] args) {      

    Boolean b1 = new Boolean("false");        

    boolean b2;        

    b2 = b1.booleanValue();    

    if (!b2) {         

      b2 = true;          

      System.out.print("x");        

    }        

    if (b1 & b2) /* Line 13 */ {       

      System.out.print("y ");     

    }        

    System.out.println("z");  

  } 

}