unix ls command in java

Question

Hi I am trying to list folders in unix "ls" command style in java. I have a folder tree like this :

My file structure is as follows :

private class Node{

    public List<Node> children= new ArrayList<Node>();
    public String value;
    public Node(String value){
        this.value = value;
    }

    public void addSubDirectory(Node child){
        children.add(child);
    }

}

Problem : I am not able to recurse more than the children of current folder when there is nothing after the ' * ' in a command

For eg. command

ls A/B/*/*/E/ and ls A/*/*/M/*/E/ works

But command " ls A/ * " only shows

B Y

Code to traverse

public void showCommand(Node root, String command){
        String argument = command.substring(3);
        System.out.println("command is ls "+argument);
        show(root,argument);   
    }
    private void show(Node root, String cmd){

        int N = cmd.length();
        if(N==0){
            // case when end of command is reached
            for(Node child:root.children){
                System.out.println(child.value);
            }
        }else{
            char c = cmd.charAt(0);
            // case when folder name is present in command
            if((c!='*') && (c!='/')){
                for(Node child:root.children){
                    if(child.value.equals(String.valueOf(c))){
                        show(child,cmd.substring(1));
                    }
                }
                return;
            }else if(c=='*'){  
            // case when * is present in command
            // i think problem lies here
                if(N==1){
                   System.out.println(root.value);
                   preOrderTraverse(root);
                }else{
                  for(Node child:root.children){
                      show(child,cmd.substring(1));
                  }
                }
                return;
            }else if(c=='/'){
            // case when '/' is present in commmand
                show(root,cmd.substring(1));
                return;
            }

        }
    }

Answer 1

When the last char in the command is a *, you call back the showCommand method with an empty cmd and when the method receives an empty cmd string the recursion stops.

When the current char c is a *, you should check it's the last char in cmd, if it is then you should send the current cmd instead of cmd.substring(1). That way it should go through the hierarchy recursively.