Using stack to make file/directory tree in Java

Question

I need to return or print a file/directory tree using stack data structure. For example:

Folder1
    Folder1.1
        File1.1.1
    Folder1.2
Folder2
    File2.1
    File2.2
...

My code so far:

public static void filetree(File mainfolder, int indent){

    Stack<String> filesanddirectories = new Stack<>();

        for (File file : mainfolder.listFiles()){
            if (file.isDirectory()){
                filesanddirectories.push(file.getName());
                filetree(file, 0);
            }
            else if (file.isFile()){
                filesanddirectories.push(file.getName());
            }
        }

    for (int i = 0; i < filesanddirectories.size(); i++){
        System.out.println(filesanddirectories.pop());
    }
}

This code prints folders and files but with no indention, backwards and not exactly in the right order.

Could someone explain the logic of how it should work?

EDIT: Found a solution using recursion and stack (although stack seems to be unnecessary)

To get the indenting working you need to add something to the indent value every time you recurse - something like filetree(file, 0); -> filetree(file, indent + 4);. You will then need to change your printing mechanism to use the indent value. — OldCurmudgeon
– OldCurmudgeon, Commented Oct 16, 2018 at 10:43
To get the file names printing correctly you need to print the file names when you see them. if (file.isFile()){filesanddirectories.push(file.getName()); -> if (file.isFile()){System.out.println(.... — OldCurmudgeon
– OldCurmudgeon, Commented Oct 16, 2018 at 10:44
Using a stack for this when you have a recursive method is somewhat unusual. Are you sure you must use a stack? — Jim Mischel
– Jim Mischel, Commented Oct 16, 2018 at 16:32

Hulya · Accepted Answer · 2018-10-20 09:05:28Z

0

I used indent and temp variables to keep the indent when traversing recursively through the file directory. Then printed indent at the start of the for loop.

public static void filetree(File mainfolder, int indent) {

        int temp;

        for (File file : mainfolder.listFiles()) {
            for(int i = 0; i<indent; i++) {
                System.out.print("  ");
            }
            temp = indent;
            if (file.isDirectory()) {

                indent++;
                System.out.println(file.getName()); 

                filetree(file, indent);
                indent--;

            } else if (file.isFile()) {

                System.out.println(file.getName());
                indent = temp;
            } 
        }
    }

edited Oct 20, 2018 at 9:05

answered Oct 16, 2018 at 19:24

Hulya

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2 Comments

Jim Mischel Over a year ago

What is the point of pushing things onto a stack if you're never going to pop them?

Hulya Over a year ago

filesanddirectories.push(file.getName()); was in OP's code, I just didn't delete the lines. Using stack has no contribution to the solution. Maybe i should update my answer.

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