Array of map? integer string value pair mapping

Question

I need to create a Integer and String paring, like

(1,one)
(2,two)
(3,three)

Later i want to iterate over it and get the String for a specific Integer value, say like if int val == 2, return String.

How can i do this?

Answer 1

Map<Integer,String> map = ...

then when you want to iterate over the keys, use

map.keySet() to get a list of Integers used as keys

Answer 2

You could model this pairing association by using a Map:

Map m = new HashMap<Integer, String>();
m.put(1, "one");
m.put(2, "two");
m.put(3, "three");

// Iterate the keys in the map
for (Entry<Integer, String> entry : m.entrySet()){
    if (entry.getKey().equals(Integer.valueOf(2)){
        System.out.println(entry.getValue());
    }
}

Take into account that by definition of Map, you couldn't have two different Strings for a given Integer. If you wanted to allow this, you should use a Map<Integer, List<String>> instead.

Notice that java doesn't provide a Pair class, but you could implement one yourself:

public class Pair<X,Y> { 
    X value1;
    Y value2;
    public X getValue1() { return value1; }
    public Y getValue2() { return value2; }
    public void setValue1(X x) { value1 = x; }
    public void setValue2(Y y) { value2 = y; }
    // implement equals(), hashCode() as needeed
} 

And then use an List<Pair<Integer,String>>.