import java.io.File;public class FileListTest {    public void tree(File file){        if(file.listFiles()!=null)//当目录File所代表的目录下存在文件时执行递归操作        {            File[] list = file.listFiles();            for(File test : list)            {                if(test.isDirectory())                {                    tree(new File(test.getAbsolutePath()+"\\"));//为目录File时进行递归                }                System.out.print(test.getAbsolutePath());            }        }    }    public static void main(String[] args) {        File file = new File("E:\\");        FileListTest test = new FileListTest();        test.tree(file);    }}