什么是java中的回调方法？术语似乎被宽松地使用 [英] What is a callback method in java? Term seems to be used loosely

问题描述

我不明白什么是回调方法，我听说人们使用这个术语非常松散。在java世界中什么是回调方法？如果有人可以提供一个带有解释的java回调方法的示例代码，这对我的Java学习之旅有很大的帮助？

I don't understand what a callback method is and I have heard people use that term very loosely. In the java world what is a call back method? If someone could provide an example code of a java callback method with an explanation, it be a great help in my java learning journey?

提前感谢。

推荐答案

回调是一段代码，它作为参数传递给其他代码，以便执行它。因为Java还不支持函数指针，所以它们被实现为Command对象。像

A callback is a piece of code that you pass as an argument to some other code so that it executes it. Since Java doesn't yet support function pointers, they are implemented as Command objects. Something like

public class Test {
    public static void main(String[] args) throws  Exception {
        new Test().doWork(new Callback() { // implementing class            
            @Override
            public void call() {
                System.out.println("callback called");
            }
        });
    }

    public void doWork(Callback callback) {
        System.out.println("doing work");
        callback.call();
    }

    public interface Callback {
        void call();
    }
}

回调函数通常会引用一些状态有用。

A callback will usually hold reference to some state to actually be useful.

通过使回调实现具有对代码的所有依赖性，您可以在代码和执行回调的代码之间获得间接。

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