using iterator to go over list of hashmaps

Question

I have a String exp, which I have to compare with the mapsList.

  String exp = "nodeId=1&&name=Router||level=1";
  List mapList = new ArrayList();

  Map map = new HashMap();
  map.put("nodeId","1");
  map.put("name","Router");
  map.put("level", "1");

  Map map1 = new HashMap();
  map1.put("nodeId","2");
  map1.put("name","Router");
  map1.put("level","2");

  Map map2 = new HashMap();
  map2.put("nodeId","3");
  map2.put("name","Router");
  map2.put("level","3");

  mapList.add(map);
  mapList.add(map1);
  mapList.add(map2);

I take the exp and split into an array.

  String delims = "[\\&&\\||\\=]+";
  String[] token = exp.split(delims);

Then I divide the array into two smaller sub arrays. One for Keys and the other for values. After which I compare ...

    if(map.keySet().contains(a1[0]) && map.keySet().contains(a1[1]) || map.keySet().contains(a1[2])){
        if(map.values().contains(a2[0]) && map.values().contains(a2[1]) || map.values().contains(a2[2])){
            System.out.println("Match\tMapKeys: "+map.keySet()+" Values: "+map.values());
        }else{
            System.out.println("No Match\t");
        }
    }

So my problem is I can do this for each map, but can't figure out how to implement it with iterator.

Can some1 push me in the right direction?

Thanks.

Answer 1

You really, really want to define an object to hold your data, instead of using HashMap s.

class Node {
    private int id;
    private String name;
    private int level;

    public Node(int id, String name, int level) {
        this.id = id;
        this.name = name;
        this.level = level;
    }

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public int getLevel() {
        return level;
    }
}

now you populate the list like this

    List<Node> nodeList = new ArrayList<Node>();

    nodeList.add(new Node(1, "Router", 1));
    nodeList.add(new Node(2, "Router", 2));
    nodeList.add(new Node(3, "Router", 3));

and you could look for your match like this

    String exp = "nodeId=1&&name=Router||level=1";

    String delims = "[\\&&\\||\\=]+";
    String[] token = exp.split(delims);

    int id = Integer.parseInt(token[1]);
    String name = token[3];
    int level = Integer.parseInt(token[5]);

    boolean match = false;

    for (Node node : nodeList) {
        if (node.getId() == id && node.getName().equals(name)
                && node.getLevel() == level) {
            System.out.println("Match found: " + node);
            match = true;
        }
    }

    if (!match) {
        System.out.println("No match");
    }

which gives me the following output

Match found: Node@1391f61c

and the next step is to implement toString .

You should check out http://docs.oracle.com/javase/tutorial/java/concepts/ as it introduces objects and why they are useful.