listing files of directory and subdirectory

[oulutas]

hi, i want to listing file 0f directory and subdirectory.
i can list file and subdirectory of directory. But, i can't listing file of subdirectory.
e.g ;

path is /home/user/

/home/user/file.html
/home/user/folder
/home/user/folder/buil.sh

yes i could listing file.html and folder. But, i want to listing to files of subfolders "/home/user/..."

how can i do ?

thanks.

 File dir = new File("/home/user");

String[] children = dir.list();
if (children == null) {
// Either dir does not exist or is not a directory
} else {
for (int i=0; i<children.length; i++) {
// Get filename of file or directory
String filename = children[i];
System.out.println(filename);
}

[eRaaaa]

how can i do ?

	public static void list(File path){
		for (File file : path.listFiles()) {
			System.out.println(file);
			if(file.isDirectory()){
				list(file);
			}
		}
	}

and call list(dir);

[oulutas]

I guess I doing something wrong. I get an error message ;

Exception in thread "main" java.lang.NullPointerException
	at ftplinuxsync.Main.list(Main.java:37)
	at ftplinuxsync.Main.main(Main.java:33)

line 33 is = Main.list(dir);
line 37 = for (File file : path.listFiles()) {

 File dir = new File("/home/madombie");
      
       Main.list(dir);

    }
    public static void list(File path){
       
		for (File file : path.listFiles()) {
			System.out.println(file);
			if(file.isDirectory()){
				list(file);
			}
		}
        
	}

[Norm]

What is printed out before the NPE?
What variable is null? Add some more print outs to show the null variable.

[oulutas]

these are all codes ;

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package javadirectory;

import java.io.File;

/**
 *
 * @author madzombie
 */
public class Main {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        File dir = new File("/home/madombie");
      list(dir);
    }
    public static void list(File path){
		for (File file : path.listFiles()) {
			System.out.println(file);
			if(file.isDirectory()){
				list(file);
			}
		}
	}

}

just print out there are ;

Exception in thread "main" java.lang.NullPointerException
        at javadirectory.Main.list(Main.java:25)
        at javadirectory.Main.main(Main.java:22)

after than add System.out.println(path); before for (File file : path.listFiles())

it is print "/home/madzombie"
but the error on 25. line. And 25. line is "for (File file : path.listFiles())"
if i add System.out.println(path.listFiles());
printing null

[Norm]

Add to your printout to show what path.listFiles() returns.

How can the program execute the print out inside the for loop if it gets the NPE on the start of the for loop?
Is the posted code, the code that you executed?
Where is the: System.out.println(path) statement?

You need to add ids to your print outs so you know which one is executing. For example:
System.out.println("path=" + path)
System.out.println('"fie=" + file);

[oulutas]

i don't understand nothing.
i add these two lines and worked.
System.out.println("path=" + path);
System.out.println('"fie=" + file);

it isn't give error.

[Norm]

Sorry, I don't understand how adding those print out lines to your program would make it work now. They should NOT change how the program works.

[Maulin Patel]

try this one...

File folder = new File("/home/user");
File[] listOfFiles = folder.listFiles();

for (int i = 0; i < listOfFiles.length; i++) {
if (listOfFiles[i].isFile()) {
System.out.println("File " + listOfFiles[i].getName());
} else if (listOfFiles[i].isDirectory()) {
System.out.println("Directory " + listOfFiles[i].getName());
}
}

[oulutas]

Sorry, I don't understand how adding those print out lines to your program would make it work now. They should NOT change how the program works.

so yes, i don't understand too.

  for (File file : path.listFiles()) {
			System.out.println("file= " + file.getName());
                        System.out.println("path= "+path);
			if(file.isDirectory()){
				list(file);
			}
		}

when delete these two lines, but I get the same error.

System.out.println("file= " + file.getName());
System.out.println("path= "+path);

If I add running. Could not give a meaning.

[Norm]

I thought the print out of the path would be the first statement in the list method, not inside of the for loop, because the value of path is NOT changed in the loop, so no need to print it every time around the loop