Java编程思想：File类list()方法

import java.util.regex.Pattern;
import java.io.File;
import java.io.FilenameFilter;

public class Test {
    public static void main(String[] args) {
        DirList.test();
        DirList2.test();
        DirList3.test();
    }
}

//方案一：实现一个FilenameFilter接口的类
class DirFilter implements FilenameFilter {

    private Pattern pattern;

    public DirFilter(String regex) {
        pattern=Pattern.compile(regex);
    }

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

class DirList {
    public static void test() {
        File path = new File("./src");
        String[] list=path.list(new DirFilter("java$"));
        System.out.println("DirList:"+list.length);
    }
}

//方案二：使用匿名内部类
class DirList2 {
    private static FilenameFilter filter(String regex) {
        return new FilenameFilter() {
            Pattern pattern = Pattern.compile(regex);
            @Override
            public boolean accept(File dir, String name) {
                return pattern.matcher(name).matches();
            }
        };
    }

    public static void test() {
        File file = new File("./src");
        String[] list = file.list(filter("java$"));
        System.out.println("DirList2:"+list.length);
    }
}

//方案三：使用匿名内部类
class DirList3 {
    public static void test() {
        File path = new File(".//src");
        String[] list = path.list(new FilenameFilter() {
            private Pattern pattern = Pattern.compile("java$");
            @Override
            public boolean accept(File dir, String name) {
                return pattern.matcher(name).matches();
            }
        });
        System.out.println("DirList3:"+list.length);
    }
}