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objects

 
Greenhorn
Posts: 12
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Dear friends,
Why these following two examples are giving different results?
Example1.java
public class Example1 {
public static void main(String[] args) {
Integer n1 = new Integer(47);
Integer n2 = new Integer(47);
System.out.println(n1.equals(n2));
}
}
result is true.

Example2.java
class Value {
int i;
}
public class Example2{
public static void main(String[] args) {
Value v1 = new Value();
Value v2 = new Value();
v1.i = v2.i = 100;
System.out.println(v1.equals(v2));
}
}
result is false.
 
Ranch Hand
Posts: 18944
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i enclose the definition as given in the API for the equals method of Object.
"The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any reference values x and y, this method returns true if and only if x and y refer to the same object (x==y has the value true)."
since the two references are to two different objects this returns false. U r thus not comparing the variables i in the objects but the objects themselves.
Hope this helps

[This message has been edited by rahul_mkar (edited May 04, 2000).]
 
Sheriff
Posts: 5782
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Yes Rahul is right.
The Integer class overrides the .equals method that
it inherits from the Object to provide content-based
comparison. However, the Value class that you have
defined does not override the equals method, and
so it is actually calling the Object.equals() method.
Hope this helps

Ajith
 
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