hashmap.containskey code example

Example 1: check if map contains key java

if (map.containsKey(key)) {
       // Okay, there's a key but the value is null
    } else {
       // Definitely no such key
    }

Example 2: TreeMap containsKey() method in java

import java.util.TreeMap;
public class TreeMapContainsKeyMethodExample
{
   public static void main(String[] args)
   {
      TreeMap<Integer, String> tm = new TreeMap<Integer, String>();
      // map String values to Integer keys
      tm.put(56, "orange");
      tm.put(62, "indigo");
      tm.put(43, "red");
      tm.put(91, "green");
      tm.put(38, "yellow");
      System.out.println("TreeMap before using containsKey() method: " + tm);
      // check for key element '62'
      System.out.println("Does key '62' present? " + tm.containsKey(62));
      // check for key element '90'
      System.out.println("Does key '90' present? " + tm.containsKey(90));
   }
}