便利map
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.TreeMap;
public class testMap {
?public static void test(String[] args) {
???? ArrayList<String> list = new ArrayList<String>();
???? HashMap<Object,Object> hash = new HashMap<Object,Object>();
???? TreeMap<Object,Object> treeMap = new TreeMap<Object,Object>();
???? list.add("a");
???? list.add("b");
???? list.add("c");
???
???? hash.put(3, 3);
???? hash.put(4, 4);
???? hash.put(5, 5);
???? hash.put(6, 6);
???? hash.put(1, 1);
???? hash.put(2, 2);
???
???? treeMap.put(1, 1);
???? treeMap.put(2, 2);
???? treeMap.put(3, 3);
???? treeMap.put(4, 4);
???? treeMap.put(5, 5);
???? treeMap.put(6, 6);
???
???? //list遍历
???? for(String m: list){
????? System.out.println(m);
???? }
???? // hashmap entrySet() 遍历
???? for(Map.Entry<Object,Object> m: hash.entrySet()){
????? System.out.println(m.getKey()+"---"+m.getValue());
???? }
???? //hashmap keySet() 遍历
???? for(Object m: hash.keySet()){
????? System.out.println(m+"---"+hash.get(m));
???? }
???? // treemap keySet()遍历
???? for(Object m: treeMap.keySet()){
????? System.out.println(m+"---"+treeMap.get(m));
???? }
??}
?
?
?public static void main(String[] args) {??
???? Map map = new HashMap();??
???? map.put("1", "a");??
???? map.put("2", "b");??
???? Iterator it = map.entrySet().iterator();??
???? while (it.hasNext()) {??
???????? Map.Entry entry = (Map.Entry) it.next();??
???????? String key = (String)entry.getKey();??
???????? String value = (String)entry.getValue();??
???????? System.out.println("key=" + key);??
???????? System.out.println("value=" + value);??
???? }??
??
?}
}
