Partial search in HashMap

Question

I need to create phone book kind of thing. It contains name & number. Now when I type letters matching list should be returned. For the example given below, when I type

Answer 1

Use guava Multimap will ease your solution.

The key is first letter of name, the value is a Collection containing all name-phone pair which name is started with the key(first letter).

Example:

    public void test(){
      //firstLetter -> list of name-phone pair
      Multimap mMap =  ArrayListMultimap.create();

      put(mMap, "Brown",  "+1236389023");
      put(mMap, "Bob",    "+1236389023");
      put(mMap, "Harmer", "+1236389023");
      put(mMap, "Harris", "+1236389023");
      put(mMap, "Hawken", "+1236389023");
      put(mMap, "Hosler", "+1236389023");

      //Test
      System.out.println(mMap.get("H"));
   }

   void put(Multimap mMap, String name, String phone){
      mMap.put(name.substring(0,1), new Pair(name, phone));
   }

   public static class Pair{
      String name;
      String phone;

      public Pair(String name, String phone) {
         this.name = name;
         this.phone = phone;
      }

      @Override
      public String toString() {
         return "Pair [name="+name+", phone="+phone+"]";
      }

}