Map That Retains Order-of-Insertion

 
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;

public class Main {
  public static void main(String[] argv) throws Exception {
    Map<String, String> map = new LinkedHashMap<String, String>();

    map.put("1", "value1");
    map.put("2", "value2");
    map.put("3", "value3");
    map.put("2", "value4");

    for (Iterator it = map.keySet().iterator(); it.hasNext();) {
      Object key = it.next();
      Object value = map.get(key);
    }
  }
}