HashMap クラス

import java.io.*;
import java.util.*;

public class Test {

	public static void main(String args[]) throws IOException
	{
		HashMap <String, Integer> a = new HashMap <String, Integer> ();
		a.put("abc", new Integer(10));
		a.put("xyz", new Integer(20));
		System.out.println(a.containsKey("abc"));
		System.out.println(a.containsValue(10));
		System.out.println(a.get("abc"));
	}
}
		
(出力)
true
true
10