Question

I have a problem with comparing two arraylist,

my first arraylist looks like this:

{TeamID=4, Group=A, TeamName=Germany}
{TeamID=6, Group=A, TeamName=Turkey}

my second list:

{TeamID=4, Chance=99.9%}
{TeamID=6, Chance=38.4%}

and then I want to create one list, which will look like this:

{TeamID=4, Group=A, TeamName=Germany Chance=99.9%}
{TeamID=6, Group=A, TeamName=Turkey Chance=38.4%}

Can You help me ?

First List:

private ArrayList<HashMap<String, String>> TeamList = this.xml.TeamListList;

Second:

private ArrayList<HashMap<String, String>> QChanceList = this.xml.QChanceListList;

Answer 1

Here’s one idea. For each team I search for the corresponding entry in the chances list, then I put all entries from both maps into a new one.

public static List<Map<String, String>> merge(
      List<Map<String, String>> teams, List<Map<String, String>> chances) {

  // create the result
  List<Map<String, String>> result = new ArrayList<Map<String, String>>();

  // now we assume that for each team there is one chance (valid?)
  for (Map<String, String> team:teams) {
    boolean success = false;
    Map<String, String> combined = new HashMap<String, String>();
    combined.putAll(team);

    String id = team.get("TeamID");

    // now we have to find the "chance" map
    for (Map<String, String> chance:chances) {
       if (chance.get("TeamID").equals(id)) {
          combined.putAll(chance);
          boolean success = true;
          break;
       }
    }

    if (!success) {
      // there was no entry in chances map with this id!! -> handle problem
    }
    result.add(combined);
  }
  return result;
}

(This example is not very fail-safe, it asserts, that all maps have values for “TeamId”, I just demonstrate that something has to be done in case of illegal input, like an incomplete chances list)