Monday 12 September 2011

Directory and File Listing Example in Java

This example illustrates how to list files and folders present in the specified directory. This topic is related to the I/O (input/output) of java.io package.
In this example we are using File class of java.io package. The File class is an abstract representation of file and directory pathnames. This class is an abstract, system-independent view of hierarchical pathnames. An abstract pathname has two components:
  1. An optional system-dependent prefix string,
    such as a disk-drive specifier, "/" for the UNIX root directory, or "\\" for a Win32 UNC pathname, and
  2. A sequence of zero or more string names.
Explanation
This program list the file of the specified directory. We will be declaring a function called dirlist which lists the contents present in the specified directory.
dirlist(String fname)
The function dirlist(String fname) takes directory name as parameter. The function creates a new File instance for the directory name passed as parameter
File dir = new File(fname); 
and retrieves the list of all the files and folders present in the directory by calling list() method on it.
String[] chld = dir.list();  
Then it prints the name of files and folders present in the directory.
Code of the Program :
import java.io.*;

public class  DirListing{
  private static void dirlist(String fname){
  File dir = new File(fname);
    String[] chld = dir.list();
  if(chld == null){
  System.out.println("Specified directory does not exist or is not a directory.");
  System.exit(0);
    }else{
  for(int i = 0; i < chld.length; i++){
  String fileName = chld[i];
  System.out.println(fileName);
  }
  }
  }
  public static void main(String[] args){
  switch(args.length){
  case 0: System.out.println("Directory has not mentioned.");
  System.exit(0);
  case 1: dirlist(args[0]);
  System.exit(0);
  default : System.out.println("Multiple files are not allow.");
    System.exit(0);
  }
  }
}
Download Directry Listing Example

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