Java Map クラスの違い HashMap Hashtable TreeMap LinkedHashMap

Map のクラス

Map サンプルコード

import java.util.Map;
public class JavaMapTest {
	static public void main(String[] arg){
		Map<String, String> hm = new HashMap();
		Map<String, String> ht = new Hashtable();
		Map<String, String> tm = new TreeMap();
		Map<String, String> lhm = new LinkedHashMap();
		setData(hm);
		setData(ht);
		setData(tm);
		setData(lhm);
		System.out.println("HashMap: " + hm);
		System.out.println("Hashtable: " + ht);
		System.out.println("TreeMap: " + tm);
		System.out.println("LinkedHashMap: " + lhm);
	}
	static private void setData(Map<String,String> m){
		m.put("2", "200");
		m.put("3", "300");
		m.put("1", "100");
		m.put("5", "a");
		m.put("6", "b");
		m.put("4", "c");
	}
}

実行結果

HashMap: {3=300, 5=a, 2=200, 4=c, 6=b, 1=100}
Hashtable: {6=b, 5=a, 4=c, 3=300, 2=200, 1=100}
TreeMap: {1=100, 2=200, 3=300, 4=c, 5=a, 6=b}
LinkedHashMap: {2=200, 3=300, 1=100, 5=a, 6=b, 4=c}

参考