Boolean wrapper class

[preeti khane]

Could someone explain , when the Boolean wrapper class equates to true / false when comparing 2 objects... I have seen that this class acts different compared to the other wrapper classes... and has some similarity with the String class (in terms of the true/false literals)

[Anupam Sinha]

Boolan objects if created by passing in a String will be true if the String passed is true(in any case). So True, TrUe, tRuE, TRUE and any other combination of cases in the same order will cause the Boolean object to contain true. Any other value will cause the wrapper to contain false. When toString is used then however the value that will be printed will be however true or false(in lowercase). Consider this :

class test {
  public static void main (String[] args)
 {
  Boolean b1=new Boolean(true);
  Boolean b2=new Boolean("true");
  Boolean b3=new Boolean("TRUE");
  Boolean b4=new Boolean("TrUe");
  Boolean b5=new Boolean("tRuE");
//   false values
  Boolean b6=new Boolean(false);
  Boolean b7=new Boolean("nottrue");
  Boolean b8=new Boolean("truetrue");
  Boolean b9=new Boolean("trueistrue");
  Boolean b10=new Boolean("false");
  System.out.println(" Value of b1 is : " + b1);
  System.out.println(" Value of b2 is : " + b2);
  System.out.println(" Value of b3 is : " + b3);
  System.out.println(" Value of b4 is : " + b4);
  System.out.println(" Value of b5 is : " + b5);
  System.out.println(" Value of b6 is : " + b6);
  System.out.println(" Value of b7 is : " + b7);
  System.out.println(" Value of b8 is : " + b8);
  System.out.println(" Value of b9 is : " + b9);
  System.out.println(" Value of b10 is : " + b10);
 }
}

Hope that helps.

[Marlene Miller]

Here is the code from Boolean.java (1.4.1)

    public boolean equals(Object obj) {
        if (obj instanceof Boolean) {
            return value == ((Boolean)obj).booleanValue();
        } 
        return false;
    }

[pinky yadav]

one more point the static valueOf(boolean) and valueOf(String) method return reference to the static Boolean object in the class Boolean.
thus the following code gives the output as:
false
true

 
class test{
 static public void main(String[] arg){Boolean b1 = new Boolean("true");
Boolean b2 = new Boolean("true");
System.out.println(b1==b2);
Boolean b3 = Boolean.valueOf(true);
Boolean b4 = Boolean.valueOf(true);
System.out.println(b3==b4);
 }
}