Java tutorial
import java.util.HashMap; import java.util.Map; public class Main { public static void main(String[] a) { Map<String, String> map = new HashMap<String, String>(); map.put("key1", "value1"); map.put("key2", "value2"); map.put("key3", "value3"); System.out.println(map.containsKey("key1")); System.out.println(map.containsValue("value2")); } }