Making a tree from two column csv file in java

manpreet Best Answer 2 years ago

I want to have ids and count of all the child of a node using two-column CSV file in which one column is parent id and one is child id.

For e.g

Child Id   Parent Id
C1         C2
C3         C1
C4         C3

I want result like this:

C2  C1, C3, C4 3

manpreet 2 years ago

It is not clear. Do you have some code or visual representation of it? If I correctly understand, You can make not tree, but just Map, where Key is ParentId and value is Integer of your Child, or Object It is possible to look like

class Child {
List<String> ids;
int count;

    public Child(String id) {
        count=1;
        if (ids.size() < 1) {
            ids = new ArrayList<>();
        }
        ids.add(id);
    }

        public Child setChild(String id) {
        if (ids.size() < 1) {
            ids = new ArrayList<>();
        }
        ids.add(id);
        count++;
        return this;
    }

class Main{

//your logic
Map<String, Child> map = new HashMap<>();
    if (!map.containsKey(parent)){
        map.put(parent,new Child(id));
    }else
    map.computeIfPresent(parent, (key, value) -> value.setChild(id));
}