java - 方法/构造函数参数的最终修饰符有什么用

Question

你好
方法/构造函数参数的最终修饰符有什么用？

例如:

class someClass {
    private final double some; // I understand the use of final in this context, immutability etc..

    public someClass(final double some) {
        // I don't understand what purpose is served by making "some" final
        this.some = some;
    }

    public void someMethod(final double some) {
        // I don't understand what purpose is served by making "some" final
    }
}

Answer 1

主要有两种情况需要:

1) 你想在本地类(通常是匿名类)中使用参数，比如:

public void foo(final String str) {
    Printer p = new Printer() {
        public void print() {
            System.out.println(str);
        }
    };
    p.print();
}

2) 当每个未修改的变量都用 final 标记时，您喜欢这种风格(通常最好保持尽可能多的东西不可变)。