Directory Listing in JAVA

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);
}
}
}