静态变量初始化java
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static variable initialization java
提问by Rohit Banga
how to initialize a private static member of a class in java.
如何在java中初始化类的私有静态成员。
trying the following:
尝试以下操作：
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.
但是在创建 A 类的第二个对象然后调用 f1() 时，我得到一个空指针异常。
采纳答案by sfussenegger
The preferred ways to initialize static members are either (as mentioned before)
初始化静态成员的首选方法是（如前所述）
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:
或者对于更复杂的初始化代码，您可以使用静态初始化程序块：
private static final B a;
static {
a = new B();
}
回答by KLE
Your code should work. Are you sure you are posting your exact code?
您的代码应该可以工作。您确定要发布确切的代码吗？
You could also initialize it more directly :
您还可以更直接地初始化它：
public class A {
private static B b = new B();
A() {
}
void f1() {
b.func();
}
}
