静态变量初始化的顺序，Java [英] Order of static variable initialization, Java

问题描述

可能重复：

Java静态类初始化

以什么顺序执行的类中的静态块和静态变量？

当我运行此代码时答案是1，我认为它将是2.
初始化的顺序和每一步中k的值是什么？

  public class Test {
 
 static {k = 2;} 
 static int k = 1; 
 
 public static void main（String [] args）{
 System.out.println（k）; 
} 
} 
  

编辑1：作为后续k是设置为默认值那么为什么下一个代码不能编译？这是一个错误在定义之前无法引用字段。

 公共类测试{
 
静态{System.out.println（k）;} 
 static int k = 1; 
 
 public static void main（String [] args）{
 System.out.println（k）; 
} 
} 
  

编辑2：对于一些我不知道的原因^当代替k而不是Test.k时有效。

感谢所有答案。这将是足够的：D

解决方案

它们按照您编写它们的顺序执行。如果代码是：

  public class Test {
 
 static int k = 1; 
 static {k = 2;} 
 
 public static void main（String [] args）{
 System.out.println（k）; 
} 
 
} 
  

然后输出变为2. / p>

初始化的顺序是： ..类的类变量初始值设定项和静态初始值设定项...，按文本顺序排列，好像它们是一个块一样。

值（对于你的代码）是：k = 0（默认值），然后它被设置为2，然后它被设置回1.

您可以通过运行以下代码来检查它实际设置为2：

 私有静态类测试{
 
 static {
 System.out.println（Test.k）; 
 k = 2; 
 System.out.println（Test.k）; 
} 
 static int k = 1; 
 
 public static void main（String [] args）{
 System.out.println（k）; 
} 
} 
  

Possible Duplicate:
Java static class initialization
in what order are static blocks and static variables in a class executed?

When I run this code the answer is 1, I thought it would be 2. What is the order of initialization and the value of k in each step?

public class Test {

static {k = 2;}
static int k = 1;

public static void main(String[] args) {
    System.out.println(k);
}
}

Edit 1: As a follow up to "k is set to default value" then why this next code doesn't compile? Theres an error "Cannot reference a field before it's defined".

public class Test {

static {System.out.println(k);}
static int k=1;

public static void main(String[] args) {
    System.out.println(k);
}
}

Edit 2: For some unknow to me reason it^ works when instead of "k" its "Test.k".

Thanks for all the answers. this will sufice :D

解决方案

They are executed in the order that you write them. If the code is:

public class Test {

    static int k = 1;
    static {k = 2;}

    public static void main(String[] args) {
        System.out.println(k);
    }

}

then the output becomes 2.

The order of initialization is: ..the class variable initializers and static initializers of the class..., in textual order, as though they were a single block.

And the values (for your code) are: k = 0 (default), then it's set to 2, then it's set back to 1.

You can check that it's actually set to 2 by running the following code:

private static class Test {

    static {
        System.out.println(Test.k);
        k = 2;
        System.out.println(Test.k);
        }
    static int k = 1;

    public static void main(String[] args) {
        System.out.println(k);
    }
}

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