Search a value for a given key in a HashMap

Question

How do you search for a key in a HashMap? In this program, when the user enters a key the code should arrange to search the hashmap for the corresponding value and

Answer 1

You wrote

HashMap hashMap = new HashMap();
...
int x = scan.nextInt();
value = hashMap.get("x");

must be:

Map<Integer, String> hashMap = new HashMap<Integer, String>();
...
int x = scan.nextInt();
value = hashMap.get(x);

EDIT or without generics, like said in the comments:

int x = scan.nextInt();
value = (String) hashMap.get(new Integer(x));

Answer 2

//If you want the key to be integer then you will have to declare the hashmap //as below :

HashMap<Integer, String> map = new HashMap<Integer, String>();
map.put(0, "x");
map.put(1, "y");
map.put(2, "z");

//input a integer value x

String value = map.get(x);

Answer 3

To decalare the hashMap use this:

 HashMap<Integer,String> hm=new HashMap<Integer,String>();

To enter the elements in the HashMap:

 hm.put(1,"January");
 hm.put(2,"Febuary");

before searching element first check that the enter number is present in the hashMap for this use the method containsKey() which will return a Boolean value:

 if(hm.containsKey(num))
 {
    hm.get(num);
 }

Answer 4

Just call get:

HashMap<String, String> map = new HashMap<String, String>();
map.put("x", "y");

String value = map.get("x"); // value = "y"