static variable initialization java

Question

how to initialize a private static member of a class in java.

trying the following:

public class A {    private static B b = null;    public A() {        if (b == null)          b = new B();    }     void f1() {          b.func();    } } 

but on creating a second object of the class A and then calling f1(), i get a null pointer exception.

Answer 1

The preferred ways to initialize static members are either (as mentioned before)

private static final B a = new B(); // consider making it final too 

or for more complex initialization code you could use a static initializer block:

private static final B a;  static {   a = new B(); } 

Answer 2

Your code should work. Are you sure you are posting your exact code?

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You could also initialize it more directly :

    public class A {        private static B b = new B();        A() {       }        void f1() {         b.func();       }     }