In the constructor I say this.file (referring to global file variable declared above) equals file (referring to the file variable name in the constructor). Then when I say addFolder(file) I get the error "The method addFolder(MainTab.Node) in the type MainTab is not applicable for the arguments (File)".

This makes sense because I am sending addFolder a file instead of a Node but when I was trying to figure out how to fix it I found out that it works with addFolder(this) but I don't understand why??? "this" should equal the same thing as file no?

1. class Node {
2.   int childCount;
3.   Node[] children;
4.   File file;
5.  
6.   Node(File file) {
7.     this.file = file;
8.    
9.     if(file.isDirectory()) {
10.       addFolder(file);
11.     }