Constructors--THIS() call

[chintan ramavat]

Hello friends,

public class Test_Constructor {

int x;
int y;
int z;

//explicit default constructor
/*Test_Constructor() {
x = 10;
y = 20;
z = 30;
System.out.println(x+ "" +y+ "" +z+ " ");
} */
// Non-default constructor

Test_Constructor(int x, int y, int z) {
this.x = x;
this.y = y;
this.z = z;

System.out.println(x+ "" +y+ ""+z+ " ");
}

Test_Constructor(){
this(10,20,0);
System.out.println(x+ "" +y+ ""+z+ " "); }

public static void main(String[] args) {

Test_Constructor t1 = new Test_Constructor();
Test_Constructor t2 = new Test_Constructor(100,200,300);

}
}

o/p - 10, 20, 0 - this is obvious
10, 20 ,0 - dont know abt this
100,200,300 - this is too

i am getting 3 answers ..can you please explain.

to my mind - 2 outputs are obvious since calling two constructors, but i am confused in the middle one. and can you please explain this() is detail if you can.

- thank you very much
- chintan ramavat

[Barry Gaunt]

Let's make your code more readable by enclosing it in [C0DE][/C0DE] tags. I have also removed the confusing commented out version of the no-argument constructor.

public class Test_Constructor {
 
        int x;
        int y;
        int z;
 
 
// Non-default constructor

Test_Constructor(int x, int y, int z) {
                this.x = x;
                this.y = y;
                this.z = z;
      
                System.out.println(x+ "" +y+ ""+z+ " ");
}

Test_Constructor(){
         this(10,20,0);
         System.out.println(x+ "" +y+ ""+z+ " ");
        }
    
public static void main(String[] args) {

Test_Constructor t1 = new Test_Constructor();
Test_Constructor t2 = new Test_Constructor(100,200,300);
                     
        }
}
    

o/p - 10, 20, 0 - this is obvious
10, 20 ,0 - dont know abt this
100,200,300 - this is too
[ May 31, 2007: Message edited by: Barry Gaunt ]

[Barry Gaunt]

You can perhaps better see that the second line is the output of the System.out.println statement immediately after the call to this(10,20,0).

[Leandro Melo]

Hi.

The following code:

Test_Constructor t1 = new Test_Constructor();

Calls two System.out.println statements: one inside the no-argument constructor and one inside the constructor with three arguments. That's why you get 10, 20, 0 output twice.

[chintan ramavat]

Thank you so much Berry and Leandro. Please pardon for the way of expressing the problem or any syntax confusion. I just want to add that,Once the No-arg constructor is done with it's values why does it print the other statement of the ARG constructor. Isn't it just completed. may be it's again a dumb question, but can you please explain if you can.

- thanks

[Nik Arora]

Hi Chintan,

Test_Constructor(int x, int y, int z) {
this.x = x;
this.y = y;
this.z = z;

System.out.println(x+ "" +y+ ""+z+ " ");
}

Test_Constructor(){
this(10,20,0);
System.out.println(x+ "" +y+ ""+z+ " "); }

public static void main(String[] args) {

Test_Constructor t1 = new Test_Constructor();
Test_Constructor t2 = new Test_Constructor(100,200,300);

}
}

o/p - 10, 20, 0 - this is obvious
10, 20 ,0 - dont know abt this
100,200,300 - this is too

i am getting 3 answers ..can you please explain.

to my mind - 2 outputs are obvious since calling two constructors, but i am confused in the middle one. and can you please explain this() is detail if you can.

Hi look at the comments below

Test_Constructor t1 = new Test_Constructor();

Test_Constructor(int x, int y, int z) {
this.x = x;
this.y = y;
this.z = z;

System.out.println(x+ "" +y+ ""+z+ " ");//Prints 10,20,0
}

Test_Constructor(){
this(10,20,0);//Calls the overloaded constructor
System.out.println(x+ "" +y+ ""+z+ " "); }//Control comes back and prints 10,20,0

Test_Constructor t2 = new Test_Constructor(100,200,300);//Overloaded constructor is called


Test_Constructor(int x, int y, int z) { //Gets Called
this.x = x;
this.y = y;
this.z = z;

System.out.println(x+ "" +y+ ""+z+ " ");//Prints 100,200,300
}


Regards
Nik

[chintan ramavat]

I got it, it's a constructor chaining
thanks very much nik,
it helped

- chintan