错误：字段名称不能声明为静态

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： The field name cannot be declared static in a non-static inner type, unless initialized with a constant expression

解决办法？

Answer 1

Java不允许您在函数局部内部类内定义非最终静态字段。只允许顶级类和静态嵌套类具有非最终静态字段。

如果您要static在Constants班级中添加一个字段，请将其放在Application班级级别，如下所示：

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();
    }
}