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what is it ?

 
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what is it ?
liem_nguyenho
post 11 Oct, 2008 - 01:54 AM
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I searched through the Internet and I see there is a new declaration, but i don't know what it is. Okie, take a look at this code:
CODE


public class testingclass {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        NewThing hbu = new NewThing();
    }

}

class NewThing {
     ////new
    {
        System.out.println("this is a new thing.");
    }
    ////new

    NewThing() {
        System.out.println("this is my constructor.");
    }
}



When i run testtingclass, "this is a new thing" is printed before "this is my constructor". Can anybody explain it to me ?
Thanks in advance.
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abgorn
post 11 Oct, 2008 - 02:46 AM
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This is because the main says to start NewThing() which has System.out.println("this is my constructor") in it. It won't run the other System.out.println because it's not in the method NewThing().

Or that's what I think you mean, what exactly is the new declaration?
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JeroenFM
post 11 Oct, 2008 - 03:01 AM
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It's called an initializer block.
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pbl
post 11 Oct, 2008 - 02:22 PM
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QUOTE(JeroenFM @ 11 Oct, 2008 - 04:01 AM) *

It's called an initializer block.


JeroenFM is right and it does not need to be ibetwenn {}

CODE

class NewThing {

        System.out.println("this is a new thing.");

    NewThing() {
        System.out.println("this is my constructor.");
    }
}


You are probably more used to constructs like:

CODE

class NewThing {

    int i = 0;
    double Pi = 3.14159;
    Rectangle rect = new Rect();
    System.out.println("this is a new thing.");

    NewThing() {
        System.out.println("this is my constructor.");
    }
}


All the code between the class declaration and the constructor is executed before the constructor is called but for static block initializer that are executed only once
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