Sort Paths in Java to a Hierarchy

Question

I have a List of n Paths and i want to create a Hierarchy ( Tree structure with objects ) out of them.

E.g. Paths :

/src/main/java/tools/mockfile/generator/data/RecordPart.java
/src/main/java/tools/mockfile/generator/Analyzer.java
/src/main/java/tools/mockfile/test/Menu.java
...

small Hierarchy :

 mockfile
    ├── generator
    │   ├── data
    │   │   └── RecordPart.java
    │   └── Analyzer.java   
    └── test
        ├── Menu.java
        └── ...

Is there any Library or Method who could help me to sort the paths to a hierarchy ? Or is the only way to split the Strings and compare all Parts and build my own Hierarchy?

You mean print out the hierarchy? Or create some kind of tree structure with objects? — Jorn Vernee, May 17 '17 at 10:15
Should be able to do this using the java.io.File class: https://docs.oracle.com/javase/7/docs/api/java/io/File.html — Michael Markidis, May 17 '17 at 10:20
@MichaelMarkidis i dont have the files local, only a list with the Paths — Drextor, May 17 '17 at 10:24
possible dublicate http://stackoverflow.com/questions/3522454/java-tree-data-structure — Mike Adamenko, May 17 '17 at 10:26
Possible duplicate of [Java tree data-structure?](http://stackoverflow.com/questions/3522454/java-tree-data-structure) — Mike Adamenko, May 17 '17 at 10:29

tobias_k · Accepted Answer · 2017-05-17T11:16:18.707

You could just use a nested Map as a tree, mapping Strings to other nested Maps. You could define a helper class just to get the type information right:

class Tree extends HashMap<String, Tree> {}
Tree tree = new Tree();

This way, the tree already comes with all the useful functionality it needs. Then, just iterate the paths and their segments and use computeIfAbsent to create new branches as needed:

List<String> paths = Arrays.asList(
        "/src/main/java/tools/mockfile/generator/data/RecordPart.java",
        "/src/main/java/tools/mockfile/generator/Analyzer.java",
        "/src/main/java/tools/mockfile/test/Menu.java");

for (String path : paths) {
    Tree node = tree;
    for (String segment : path.split("/")) {
        node = node.computeIfAbsent(segment, s -> new Tree());
    }
}

Afterwards, the tree looks like this (indentation mine; note that the root is empty string):

 {={src={main={java={tools={mockfile={test={Menu.java={}},
                                      generator={data={RecordPart.java={}}, 
                                                 Analyzer.java={}}}}}}}}}

Alternatively, you could e.g. put null for files (leaves) instead of another empty Tree.

score 0 · Answer 2 · answered May 17 '17 at 10:29

0

If you desire to create and manipulate tree structure the ad hoc library is Jgrapht.

answered May 17 '17 at 10:29

Denis Ismailovski

311
1
7
15

Sort Paths in Java to a Hierarchy

2 Answers2