"this" and with out "this" Keyword

[munnanext]

package p2;

public class Test1 {
boolean temp;
int i;
/** Creates a new instance of Test1 */
public Test1(int i) {
System.out.println(i);
this.i = i;
}

public static void main(String args[]){

Test1 objTest1 = new Test1(5);
System.out.println(objTest1.i);
}


}

This Program Prints 5 and 5

But when I do small modification to the above program (by removing this key word)

package p2;

public class Test1 {
boolean temp;
int i;
/** Creates a new instance of Test1 */
public Test1(int i) {
System.out.println(i);
i = i; // Here I removed this Key Word
}

public static void main(String args[]){

Test1 objTest1 = new Test1(5);
System.out.println(objTest1.i);
}


}

I am getting output as 5 and 0.

Can you explain me why this is happening. I am expecting 5 and 5 in both cases.

Tahnks

 

[sedj]

Within your Test1 constructor, the int "i" that is passed in is local to that method - ie it has nothing to do with the class level "i" variable. So when you say "i = i", all you are saying is "my local variable i = my local variable i".

When you add the "this" keyword, you are saying "my class variable i = my local variable i".

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[chiph]

One handy thing to do is when you see the keyword "this", mentally say: "this instance of my class". It'll help you keep things straight in your head.

Chip H.


____________________________________________________________________
If you want to get the best response to a question, please read FAQ222-2244 first

 

[munnanext]

I understnad this thanks.