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The == operator

Per Radfe
Greenhorn

Joined: Jul 05, 2007
Posts: 14
import java.util.ArrayList;
import java.util.Vector;
class Main extends Thread{
public static void main(String[] args) {

Vector<Integer> x = new Vector<Integer>();
ArrayList<Double> y = new ArrayList<Double>();

if ( x == y){
System.out.println("test");
}
}
}

This code dose´┐Żnt compile. I thought that you could compare any reference variable but obviously not? Is the == operator working like instanceof wich only can compare instances of the same class hierarchy?
Nousheed Mohammed
Greenhorn

Joined: Mar 30, 2007
Posts: 6
Yes, Using == operator we can compare instances of the same class.
Per Radfe
Greenhorn

Joined: Jul 05, 2007
Posts: 14
Ok, thanks.
 
It is sorta covered in the JavaRanch Style Guide.
 
subject: The == operator