Java Declare a variable and then initialize it.?

Question

public class TestVariableDeclaration{
    int j;  // ERROR
    j=45;   // ERROR

    static{
        int k;
        k=24;

    }

    {

        int l;
        l=25;
    }

    void local(){
        int loc;
        loc=55;
    }

}

In the above why can't I declare a variable "j" and then initialize directly under a class
I can declare and then initialize in the same manner under a Method,Static/Instance initialization block?
What makes the difference, I am aware about the fact that Java does not support Declaring and then initializing a instance variable. What's the reason behind that??

May i know the reason why declaration and then initialization of the variable is not possible?? — Jp Reddy
– Jp Reddy, Commented Oct 8, 2013 at 7:08
because at the possion where you wrote j=45; only declarations are allowed but not statements. — Marco Forberg
– Marco Forberg, Commented Oct 8, 2013 at 7:10

Hajo Thelen · Accepted Answer · 2013-10-11 08:00:34Z

2

you can declare on class level with int j = 45; as mentioned by Subhrajyoti Majumder
k is in a special function/method, call it the static initializer. it is executed when class is loaded. k is only known inside this method
l is in a special method which is executed on class instantiation. l is only known in this method.

This is very basic java stuff.

(edit:typos)

edited Oct 11, 2013 at 8:00

answered Oct 8, 2013 at 7:12

Hajo Thelen

1,1351 gold badge11 silver badges17 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

anubhava · Accepted Answer · 2013-10-08 07:12:18Z

0

You cannot use a variable before declaring it under normal circumstances. So

j=45;

at the top will fail since j hasn't been declared yet.

Unless I am not getting your question, this is very much possible with:

class SomeClass {
    int j; // declare it
    {
        j=45; // initialize it
    }
}

OR even more concise:

class SomeClass {
    int j = 45; // declare and initialize
}

answered Oct 8, 2013 at 7:12

anubhava

790k67 gold badges603 silver badges671 bronze badges

Comments

Sid · Accepted Answer · 2013-10-08 07:13:34Z

0

Why dont you simply initialize and declare it together like this -> int j=45;? It works that way for me..

answered Oct 8, 2013 at 7:13

Sid

3712 silver badges12 bronze badges

Collectives™ on Stack Overflow

Java Declare a variable and then initialize it.?

3 Answers 3

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related