Node hierarchy from directory path list - kotlin

Question

Hi I'm trying to build a node hierarchy based on the directory structure:
/first/
/first/second
/first/third
/first/third/forth
/first/third/fifth
/first/sixth
/first/sixth/seventh
/first/eighth
/first/ninth
I'm trying to get a node hierarchy similar to this:
first
second
third
forth
fifth
sixth
seventh
eighth
ninth
I'm using Kotlin for this, I'm still relatively new to Java and Kotlin so bear with me.
Note: I'm using FileTreeWalk to get the directories
fun getDirs(directoryName: String): MutableList<String> {
val ret = mutableListOf<String>()
File(directoryName).walk().forEach {
if (it.isDirectory) { ret.add(it.toString()) }
}
return ret
}
Right now all I have is this (Generates a flat hierarchy):
private fun nodesFromPathList(dirPaths: MutableList<String>) : Tree.Node {
val ret = Tree.Node("root")
for (dir in dirPaths) {
ret.add(Tree.Node(dir))
}
return ret
}
Any ideas?

Answer 1

I decided to put all the nodes into a map and connect the nodes together.
/**
* Creates a node hierarchy from list of paths
*/
private fun nodesFromPathList(dirPaths: MutableList<String>) : Tree.Node? {
var ret : Tree.Node? = null
val nodeMap = mutableMapOf<String, Tree.Node>()
// Add a node for each directory path and put it into a map
for (dir in dirPaths) {
val newNode = Tree.Node(nodeName(dir), skin)
if (ret == null)
ret = newNode
nodeMap.put(dir, newNode)
}
// Go through each one and add the child
nodeMap.forEach {
val parent = parentPath(it.key)
try {
nodeMap[parent]!!.add(it.value)
} catch (e: NullPointerException) {
println("Parent not found")
}
}
return ret
}
/**
* Returns current path
* "D:\dir\to\apath" ==> "apath"
*/
fun nodeName(path: String): String {
return path.split("\\").last()
}
/**
* Returns the parent path
* D:\dir\to\apath ==> D:\dir\to
*/
fun parentPath(path: String): String {
val split = path.trim('\\').split("\\")
var ret = ""
for (i in 0..split.size-2) {
ret += split[i] + "\\"
}
return ret.trim('\\')
}
I put the path into the key, and the tree node into the value. Iterated through the map and connected the children based on the parent. Example Map.:
[D:\android\assets=Tree$Node#56eb1af5,
D:\android\assets\Assets\abc=Tree$Node#48e3456d,
D:\android\assets\Assets\abc\bcd=Tree$Node#3e532818,
D:\android\assets\Assets\abc\cde=Tree$Node#16b07083]
I would find the parent from the key (by splitting the string), then set the parent.