35.File

        //构造方法1:
        File file1 = new File("E://abc/a.txt");
        //构造方法2:
        File file2 = new File("E://abc","a.txt");
        //构造方法3:
        File file = new File("E://abc");
        File file3 = new File(file, "a.txt");
        System.out.println(file1);//E:\abc\a.txt
        System.out.println(file2);//E:\abc\a.txt
        System.out.println(file3);//E:\abc\a.txt

        //构造方法1:
        File file1 = new File("D://abc/a.txt");
        //构造方法2:
        File file2 = new File("D://abc","a.txt");
        //构造方法3:
        File file = new File("D://abc");
        File file3 = new File(file, "a.txt");
        File file4 = new File("D://file//test");
        
        System.out.println(file.mkdir());//true
        System.out.println(file1.createNewFile());//true
        System.out.println(file4.mkdirs());//true

 File file = new File("D://abc/a.txt");
        System.out.println(file.isFile());//true
        System.out.println(file.isDirectory());//false
        System.out.println(file.exists());//true
        System.out.println(file.getAbsolutePath());//D:\abc\a.txt
        System.out.println(file.getPath());//D:\abc\a.txt
        System.out.println(file.getName());//a.txt
        File dir = new File("D://abc");
        for (String s:dir.list()){
            System.out.println(s);
            /**
             * a
             * a.txt
             * b
             */
        }
        for (File f:dir.listFiles()){
            System.out.println(f);
            /**
             * D:\abc\a
             * D:\abc\a.txt
             * D:\abc\b
             */
        }