java - java中的回调是什么？

Question

我这里有这段代码。 (此代码摘自《Thinking in Java 4th Edition》)

//{Args: "D.*\.java}
import  java.util.regex.*;
import java.io.*;
import java.util.*;

public class DirList {
    public static void main (String[] args){
        File path = new File(".");
        String[] list;
        if(args.length == 0)
            list = path.list();
        else
            list = path.list(new DirFilter(args[0]));

        Arrays.sort(list,String.CASE_INSENSITIVE_ORDER);
        for(String dirItem : list ){
            System.out.println(dirItem);
        }
    }
}

class DirFilter implements FilenameFilter{
    private Pattern pattern;
    public DirFilter(String regex){
        pattern = Pattern.compile(regex);
    }

    public boolean accept(File Dir,String name){
        return pattern.matcher(name).matches();
    }
}

然后当我阅读它的解释时我遇到了这个

DirFilter’s sole reason for existence is to provide the accept( ) method to the list( ) method so that list( ) can "call back" accept( ) to determine which file names should be included in the list. Thus, this structure is often referred to as a callback.

回调具体是什么？

Answer 1

回调是您向正在使用的库提供的一种方法，以便该库可以调用您的方法来执行工作(或者更确切地说，回调您的代码，从而得名)。

更一般地说，任何两层代码都可以通过回调函数进行交互。