equals() ?

[Muhammad Asif]

class test{
public static void main(String arg[]){
ice ob=new ice("5");
ice oc=new ice("5");
System.out.println(ob.equals(oc)); //1
Integer i=new Integer(5);
Integer j=new Integer(5);
System.out.println(i.equals(j)); //2
}
}
class ice{
ice(String s){
}
}
//1 : printout false
//2 : printout true
Why equals operator behaves differently. I know that the reference of ice object is different.Why it didn�t compare the content of ice object? And why it compare the content of Integer object?

[Jonathan Jeban]

Hi Asif,
For ice object the equals() method of the Object class is not overridden.
For Integer object the equal() method is overriden.
Hope this helps..
Jeban.

[Muhammad Asif]

Hi Jeban
Thanx for reply.One thing more how we distinguish that equals() overide or not.

[bill bozeman]

Need to go through the API for that one. If you create the class, you will need to override it yourself obviously, but for the other classes, go through the API and see if it is overridden. I believe all of the wrapper classes have an equal() method that should do what you want.

[Muhammad Asif]

Hi bozeman,
Got it.Thanx.
Regards,
Asif

[Ahmad Mudassir]

Any body can tell me that can we compare StringBuffer to String object through equals method
StringBuffer sb1 = new StringBuffer("Amit");
StringBuffer sb2= new StringBuffer("Amit");
String ss1 = "Amit";
System.out.println(sb1==sb2);
System.out.println(sb1.equals(sb2));
System.out.println(sb1.equals(ss1)); //this one
System.out.println("Poddar".substring(3));
Thanx

[Ajith Kallambella]

Since <code>equals</code> method is defined on <code>Object</code> class, you can call it on any class ( since all classes derive from <code>Object</code> ). However if the class on which it is being called does not provide( "override" ) its own version of the method, then you will see the default behaviour which is reference-based comparison.
So, to answer your question, yes you can call the <code>equals</code> on the <code>StringBuffer</code> class passing in a <code>String</code> object. If you are wondering why it returns false, take a look at API documentation for the
<code>StringBuffer</code> class.
Ajith