java中讲讲File的用法，举例？

2.1 File的用法 

马 克-to-win：sun公司设计File类，本身不能用来读数据或写数据。（要想读写数据，必须和其它io流的类配合使用，比如 FileInputStream等）File类的功能就是对磁盘上的文件或目录做一些非读写方面的工作，比如看看文件在哪个目录，哪天创建的，创建个新空 文件等。

例：2.1.1


import java.io.*;
public class TestMark_to_win {

    public static void main(String args[]) throws Exception {
/*File(String parent, String child) Creates a new File instance from a
parent pathname string and a child pathname string.the parent  pathname is taken to denote a directory, and the child pathname string is taken to denote either a directory or a file.  */
        File f1 = new File("c:\\tmp", "tmp\\1.txt");
 //File f1=new File("1.txt");
/*getName就是lastname*/
        System.out.println("getName is " + f1.getName());
/* getPath Returns: The string form of this abstract pathname。即原样返回。 */
        System.out.println("getPath is" + f1.getPath());
/* getAbsolutePath: Returns the absolute pathname string of this
abstract pathname. If this abstract pathname is already absolute,
then the pathname string is simply returned as if by the getPath()
method.if you use File f1=new File("1.txt"); you can see the
difference.结果会变成
getName is 1.txt
getPath is1.txt
Absolute Path is D:\eclipseJee\t1\1.txt
not */
        System.out.println("Absolute Path is " + f1.getAbsolutePath());
        System.out.println(f1.exists() ? "exist" : "not");
    }
}
结果是：
getName is 1.txt
getPath isc:\tmp\tmp\1.txt
Absolute Path is c:\tmp\tmp\1.txt
not

 

例：2.1.2

import java.io.*;
public class TestMark_to_win {
    public static void main(String[] args) {
        File path = new File("c:/");
        /*Returns an array of strings naming the files and directories .*/
        String[] list = path.list();
        for (int i = 0; i < list.length; i++)
            System.out.println(list[i]);
    }
}

更多请见：https://blog.youkuaiyun.com/qq_44639795/article/details/102568855