HashMap,LinkedHashMap,TreeMap使用源
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package com.lrm.study.testcase;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.TreeMap;
public class MapAppTest {
public static void main(String[] args) {
MapAppTest.noOrder();
MapAppTest.hasOrder();
MapAppTest.likedHashMap();
}
public static void noOrder() {
System.out.println("------无序（随机输出------");
Map map = new HashMap();
map.put("1", "Level 1");
map.put("2", "Level 2");
map.put("3", "Level 3");
map.put("4", "Level 4");
map.put("F", "Level F");
map.put("Q", "Level Q");
Iterator it = map.entrySet().iterator();
while (it.hasNext()) {
Map.Entry e = (Map.Entry) it.next();
System.out.println("Key: " + e.getKey() + "; Value: "
+ e.getValue());
}
}
public static void hasOrder() {
System.out.println("------有序（但是按默认顺充，不能指定）------");
Map map = new TreeMap();
map.put("F", "Level F");
map.put("7", "Level 1");
map.put("8", "Level 2");
map.put("4", "Level 3");
map.put("4", "Level 4");
map.put("Q", "Level Q");
map.put("E", "Level E");
Iterator it = map.entrySet().iterator();
while (it.hasNext()) {
Map.Entry e = (Map.Entry) it.next();
System.out.println("Key: " + e.getKey() + "; Value: "
+ e.getValue());
}
}
public static void likedHashMap() {
System.out.println("------有序（根据输入的顺序输出）------");
Map map = new LinkedHashMap();
map.put("F", "Level F");
map.put("7", "Level 1");
map.put("8", "Level 2");
map.put("4", "Level 3");
map.put("4", "Level 4");
map.put("Q", "Level Q");
map.put("E", "Level E");
Iterator it = map.entrySet().iterator();
while (it.hasNext()) {
Map.Entry e = (Map.Entry) it.next();
System.out.println("Key: " + e.getKey() + "; Value: "
+ e.getValue());
}
}
}
输入结果：------无序（随机输出------Key:3;Value:Level3Key:F;Value:LevelFKey:2;Value:Level2Key:4;Value:Level4Key:Q;Value:LevelQKey:1;Value:Level1------有序（但是按默认顺充，不能指定）------Key:4;Value:Level4Key:7;Value:Level1Key:8;Value:Level2Key:E;Value:LevelEKey:F;Value:LevelFKey:Q;Value:LevelQ------有序（根据输入的顺序输出）------Key:F;Value:LevelFKey:7;Value:Level1Key:8;Value:Level2Key:4;Value:Level4Key:Q;Value:LevelQKey:E;Value:LevelE
