access variable in constructor.

[Guoqiao Sun]

Please help with the following code:

public class Test
{
    int y = 0;
    
    public Test() 
    {
        //this(y); //not compile
    }
    
    public Test(int val) 
    {
        this.y = 0;
    }
}

I don't know why <code>this(y)</code> does not compile?
Please help, thanx in advance.
Guoqiao

[Anonymous]

I found it will work, if you write like this:
public class test {

int y = 0;
public test(){
//this(y), Compiler Error!
}
public test(int x){
this();
y = 1;
}
}
I think compiler must insert super() in that "Compiler Error"
place.
Error Message: You cannot use y before parent class not initial.
------------------
I love MySQL!

[Guoqiao Sun]

No, if I uncomment the <code>this(y);</code>, the error is as:
<code>
Test.java [19:1] Can't reference y inside this() call
this(y); //not compile

^
1 error
</code>
Please give explanation.
Guoqiao

Originally posted by pcedar:
I found it will work, if you write like this:
public class test {

int y = 0;
public test(){
//this(y), Compiler Error!
}
public test(int x){
this();
y = 1;
}
}
I think compiler must insert super() in that "Compiler Error"
place.
Error Message: You cannot use y before parent class not initial.

[Anonymous]

Originally posted by Guoqiao Sun:
[B]Please help with the following code:

public class Test
{
    int y = 0;
    
    public Test() 
    {
        //this(y); //not compile
    }
    
    public Test(int val) 
    {
        this.y = 0;
    }
}

I don't know why this(y) does not compile?
Please help, thanx in advance.
Guoqiao

Compiles no since it is illegal to reference things like that.
(read the compiler output!)
Why dont you do like this:

public class Test{    
   int y;
   public Test() {        
      this(0);    
   }        
   public Test(int val) {        
      this.y = val;    
   }
}

But then again we still dont gain anything from here.

------------------
Antti Barck
It Solutions Consultant, NSD Oy

[Desai Sandeep]

Hi Antti,
As you have shown in your code :
<pre>
public class Test {
int y;
public Test() {
this(0);
}
public Test(int val) {
this.y = val;
}
}
</pre>
The advantage of using this(0) is to initialize the property(attribute) of Test object to a default value if the client chooses not to specify the value of y.I have used this often to do some initialization of my object before calling its methods.
Hope this helps,
Sandeep
SCJP2, OCSD(JDeveloper), OCED(Oracle Internet Platform)