How to execute multiple constructor, when creating single object

Question

I want to execute multiple constructor, while creating a single object. For example, I have a class definition like this-

public class Prg
{
    public Prg()
    {
        System.out.println("In default constructor");
    }
    public Prg(int a)
    {
        System.out.println("In single parameter constructor");
    }
    public Prg(int b, int c)
    {
        System.out.println("In multiple parameter constructor");
    }
}

And I am trying to achieve it by the following code -

public class Prg
{
    public Prg()
    {
        System.out.println("In default constructor");
    }
    public Prg(int a)
    {
        Prg();
        System.out.println("In single parameter constructor");
    }
    public Prg(int b, int c)
    {
        Prg(b);
        System.out.println("In multiple parameter constructor");
    }
    public static void main(String s[])
    {
        Prg obj = new Prg(10, 20);
    }
}

But in this case it is generating errors like -

Prg.java:11: error: cannot find symbol
            Prg();
            ^
  symbol:   method Prg()
  location: class Prg
Prg.java:16: error: cannot find symbol
            Prg(b);
            ^
  symbol:   method Prg(int)
  location: class Prg
2 errors

Thanks

score 14 · Accepted Answer · edited Sep 25 '13 at 08:35

14

Use this() instead of Prg() in your constructors

edited Sep 25 '13 at 08:35

Prasad Kharkar

13,410
5
37
56

answered Sep 25 '13 at 08:16

Manuel Manhart

4,819
3
24
28

1

Oh, thanks. I was searching for keywords like super, to point the same class. But I didn't tried this. Now it's working. – CodeCrypt Sep 25 '13 at 08:19

score 6 · Answer 2 · answered Sep 25 '13 at 08:17

Use this instead of Prg

    public Prg()
    {
        System.out.println("In default constructor");
    }
    public Prg(int a)
    {
        this();
        System.out.println("In single parameter constructor");
    }
    public Prg(int b, int c)
    {
        this(b);
        System.out.println("In multiple parameter constructor");
    }

SpringLearner · Answer 3 · 2013-09-25T08:27:21.893

use this keyword.Full running code is as follows

public class Prg
{
    public Prg()
    {
        System.out.println("In default constructor");
    }
    public Prg(int a)
    {
        this();
        System.out.println("In single parameter constructor");
    }
    public Prg(int b, int c)
    {
        //Prg obj = new Prg(10, 20);

this(b);        System.out.println("In multiple parameter constructor");
    }
    public static void main(String s[])
    {
        Prg obj = new Prg(10, 20);
    }
}

score 3 · Answer 4 · answered Sep 25 '13 at 08:17

3

You should use this statement.

e.g.

public Prg(int b, int c)
{
    this(b);
    System.out.println("In multiple parameter constructor");
}

answered Sep 25 '13 at 08:17

Jayamohan

12,734
2
27
41

score 2 · Answer 5 · edited Sep 25 '13 at 08:18

2

When calling other constructors Use this() instead of Prg()

edited Sep 25 '13 at 08:18

Prasad Kharkar

13,410
5
37
56

answered Sep 25 '13 at 08:17

ahmedalkaff

313
1
3

How to execute multiple constructor, when creating single object

5 Answers5

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