File 클래스의 구성 방법 및 공통 기능 소개

File file = new File("yyy.txt");		//可以加后缀，也可以不加后缀
    System.out.println(file.createNewFile());

File dir1 = new File("aaa");			//创建文件夹
        System.out.println(dir1.mkdirs());

File dir2 = new File("bbb.txt");    		//文件夹也可以加后缀
        System.out.println(dir2.mkdirs()); 
 
File dir3 = new File("ccc\\ddd");   
        System.out.println(dir3.mkdirs());  //创建多级目录（文件夹）

        File file1 = new File("xxx.txt");
        File file2 = new File("ooo.txt");
        System.out.println(file1.renameTo(file2));
        File file3 = new File("D:\\XXX.txt");
        System.out.println(file2.renameTo(file3));

	File file1 = new File("yyy.txt");
        System.out.println(file1.delete());     //true
 
        File file2 = new File("aaa");
        System.out.println(file2.delete());     //true
 
        File file3 = new File("ccc");       	//如果删除一个文件夹，那么此文件夹必须为空
        System.out.println(file3.delete());     //false

public static void main(String[] args) {
        File dir =  new File("D:\\");
        String[] arr = dir.list(new FilenameFilter(){
 
            @Override
            public boolean accept(File dir, String name) {
                //System.out.println(dir);      dir是盘符D盘
                //System.out.println(name);     name是文件名
                File file = new File(dir,name);
                return file.isFile() && file.getName().endsWith(".txt");
            }
        });
        //数组里存储的全是符合条件的
        for (String string : arr) {
            System.out.println(string); //BugReport.txt
        }
    }