CODEWITHSUNDEEP
javadynamicarraylist
elect
elect

Reputation: 7190

Java: ordering an arraylist dynamically

I have an arraylist of several items. An item may have a specific int field LYING equal to OFF, FLOOR, RB1, RB2, RB3 or RB4.

For example OFF is defined as:

public static final int OFF = 0;

Regarding some specific global variables I would like to order those elements in a custom way, that may be for example:

Which is the best solution for my case?

Focusing on writing some custom:

public int compare(Object o1, Object o2) {
    if(globalVariable0 > 0) {
        if(o1.getLying() == o2.getLying)
            return 0;
        if(o1.getLying() == RB1 && o2.getLying != RB1)
            return -1;
        ...
    }else{
        ...
    }

or..?

Upvotes: 1

Views: 132

Answers (2)

pgras
pgras

Reputation: 12780

From your question I understand that you wnat to group elements by their LYING.

I would then keep several lists, one for each LYING... You could also an Enum for the different LYINGs.

You could store your elements in a Multimap, or use, for example:

static enum Lying {
    OFF, FLOOR, RB1, RB2, RB3, RB4
}

EnumMap<Lying , List<MyElements>> myElements = ...

Upvotes: 0

Roland
Roland

Reputation: 5438

There are probably several solutions for this but since we are talking about an "unnatural" order I'd hold an object with the correct order, for example a map that I can query for sortposition in my compare method, then the sortorder could be easy to edit in a properties-file maybe. Perhaps like this:

public int compare(Object o1, Object o1){
  ActualType a1 = (ActualType) o1;
  ActualType a2 = (ActualType) o2;
  SortedOrderMap map = getSortOrderMap(); //cached of course
  Integer l1 = map.get(a1.getLying());
  Integer l2 = map.get(a2.getLying());
  return l1.compareTo(l2);
}

Upvotes: 2

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