java.io.File中一些函数的学习

Example

public static long diskUsage(File root){    long total = root.length();    if(root.isDirectory()){        for(String childname: root.list()){            File child = new File(root, childname);            total += diskUsage(child);        }    }    return total;}public static void main(String[] args){    System.out.println(diskUsage(new File("/Users/zhongwen/Desktop/ForDreamForFuture/mycode")));}

用到的Methods

• new File(pathString) or new File(parentFile, childString)
  A new File instance can be constructed either by providing the full path as a string,
  or by providing an existing File instance that represents a directory and a string that designates the name of a child entry within that directory.
  also,
  File(String parent, String child)
  Creates a new File instance from a parent pathname string and a child pathname string.

• file.length()
  Returns the length of the file denoted by this abstract pathname.

• file.isDirectory()
  Tests whether the file denoted by this abstract pathname is a directory.

• file.list()
  Returns an array of strings naming the files and directories in the directory denoted by this abstract pathname.

ps：在terminal中查看某个文件夹的disk usage的命令是 du -a filepath