java - 错误 : field name cannot be declared static

Question

public class Application {
    public static void main(String[] args) {
        final class Constants {
            public static String name = "globe";
        }
        Thread thread = new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println(Constants.name);
            }
        });
        thread.start();
    }
}

编译错误:字段名称不能在非静态内部类型中声明为静态，除非用常量表达式初始化

解决这个问题？

Answer 1

Java 不允许您在局部函数内部类中定义非最终静态字段。仅顶级类和静态嵌套类允许具有非最终静态字段。

如果你想在你的Constants类中有一个static字段，把它放在Application类级别，像这样:

public class Application {
    static final class Constants {
        public static String name = "globe";
    }
    public static void main(String[] args) {
        Thread thread = new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println(Constants.name);
            }
        });
        thread.start();
    }
}