Store an array in HashMap

Question

i'm new to Java. How can i store an array of integers values in a HashMap, after that i write this HashMap in a txt file but this isn't important at the moment. I can store single fields but not an array. Any ideas ?

public void salveazaObiectulCreat(String caleSpreFisier) {

    HashMap map = new HashMap();

    map.put ("Autorul",numelePrenumeleAutorului);
    map.put ("Denumirea cartii",denumireaCartii);
    map.put ("Culoarea cartii",culoareaCartii);
    map.put ("Genul cartii",gen);
    map.put ("Limba",limba);
    map.put ("Numarul de copii",numarulDeCopii);
    map.put ("Numarul de pagini",numarulDePagini);
    map.put ("Pretul cartii",pretulCartii);

  try  {

      File file = new File(caleSpreFisier);  

      FileOutputStream f = new FileOutputStream(file);  

      ObjectOutputStream s = new ObjectOutputStream(f);          

      s.writeObject(map);

      s.close();

       } catch(Exception e){

           System.out.println("An exception has occured");     
    }   
}

Answer 1

Your life will be much easier if you can save a List as the value instead of an array in that Map.

Answer 2

You can store objects in a HashMap.

HashMap<String, Object> map = new HashMap<String, Object>();

You'll just need to cast it back out correctly.

Answer 3

HashMap<String, List<Integer>> map = new HashMap<String, List<Integer>>();
HashMap<String, int[]> map = new HashMap<String, int[]>();

pick one, for example

HashMap<String, List<Integer>> map = new HashMap<String, List<Integer>>();
map.put("Something", new ArrayList<Integer>());
for (int i=0;i<numarulDeCopii; i++) {
    map.get("Something").add(coeficientUzura[i]); 
}

or just

HashMap<String, int[]> map = new HashMap<String, int[]>();
map.put("Something", coeficientUzura);

Answer 4

Not sure of the exact question but is this what you are looking for?

public class TestRun
{
     public static void main(String [] args)
     {
        Map<String, Integer[]> prices = new HashMap<String, Integer[]>();

        prices.put("milk", new Integer[] {1, 3, 2});
        prices.put("eggs", new Integer[] {1, 1, 2});
     }
}

Answer 5

Yes, the Map interface will allow you to store Arrays as values. Here's a very simple example:

int[] val = {1, 2, 3};
Map<String, int[]> map = new HashMap<String, int[]>();
map.put("KEY1", val);

Also, depending on your use case you may want to look at the Multimap support offered by guava.

Answer 6

If you want to store multiple values for a key (if I understand you correctly), you could try a MultiHashMap (available in various libraries, not only commons-collections).