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优化代码

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This commit is contained in:
xuwujing
2018-12-06 13:46:04 +08:00
parent 662ece7e19
commit b045bd6403
3 changed files with 165 additions and 123 deletions
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247
src/main/java/com/pancm/basics/MapTest.java
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@@ -1,123 +1,124 @@
package com.pancm.basics;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.TreeMap;
/**
*
* Title: MapTest
* Description:集合map测试
* Version:1.0.0
* @author pancm
* @date 2017年11月16日
*/
public class MapTest {
private static Map<String,String> map = new HashMap<String,String>();
public static Map<String,String> getHashMap(){
if(map == null || map.isEmpty()){
map = new HashMap<String,String>();
}
return map;
}
public static void main(String[] args) {
//普通的HashMap
// Map<String,String> map=mapTest.getHashMap();
// map.put("a", "1");
// map.put("b", "1");
// map.put("c", "e");
// System.out.println(map.toString());
// Map<String,String> map1=mapTest.getHashMap();
// System.out.println("-----"+map1.get("a"));
//上锁的HashMap
// Map<String,String> sMap=Collections.synchronizedMap(new HashMap());
// getMap1();
test1();
test2();
}
private static void test1() {
Map<String, String> map = new HashMap<String, String>();
map.put("1", "value1");
map.put("2", "value2");
map.put("3", "value3");
//第一种：普遍使用，二次取值
System.out.println("通过Map.keySet遍历key和value：");
for (String key : map.keySet()) {
System.out.println("key= "+ key + " and value= " + map.get(key));
}
//第二种 使用迭代器Iterator进行遍历
System.out.println("通过Map.entrySet使用iterator遍历key和value：");
Iterator<Map.Entry<String, String>> it = map.entrySet().iterator();
while (it.hasNext()) {
Map.Entry<String, String> entry = it.next();
System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
}
//第三种：使用entrySet遍历 推荐，尤其是容量大时
System.out.println("通过Map.entrySet遍历key和value");
for (Map.Entry<String, String> entry : map.entrySet()) {
System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
}
}
private static void test2() {
Map<String,Object> hashMap=new HashMap<String,Object>();
hashMap.put("a", 1);
hashMap.put("c", 3);
hashMap.put("b", 2);
System.out.println("HashMap:"+hashMap);
Map<String,Object> treeMap=new TreeMap<String,Object>();
treeMap.put("a", 1);
treeMap.put("c", 3);
treeMap.put("b", 2);
System.out.println("TreeMap:"+treeMap);
}
private static void getMap1(){
Map<Integer,Integer> map1 =new HashMap<Integer,Integer>();
Map<Integer,Integer> map2 =new HashMap<Integer,Integer>();
map1.put(1, 1);
map1.put(2, 2);
map1.put(3, 3);
map2.put(11, 11);
map2.put(22, 22);
map2.put(33, 33);
Map<Integer,Map<Integer,Integer>> map3 =new HashMap<Integer,Map<Integer,Integer>>();
map3.put(1, map1);
map3.put(2, map2);
System.out.println("map3:"+map3);
StringBuffer sb=new StringBuffer();
for(Entry<Integer,Map<Integer,Integer>> entry:map3.entrySet()){
sb.append(entry.getKey());
sb.append(":");
Map<Integer,Integer> map4=entry.getValue();
for(Entry<Integer,Integer> entry1:map4.entrySet()){
sb.append(entry1.getKey());
sb.append("_");
sb.append(entry1.getValue());
sb.append(",");
}
}
sb.deleteCharAt(sb.lastIndexOf(","));
System.out.println("sb:"+sb);
}
}
package com.pancm.basics;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.TreeMap;
/**
*
* Title: MapTest
* Description:集合map测试
* Version:1.0.0
* @author pancm
* @date 2017年11月16日
*/
public class MapTest {
private static Map<String,String> map = new HashMap<String,String>();
public static Map<String,String> getHashMap(){
if(map == null || map.isEmpty()){
map = new HashMap<String,String>();
}
return map;
}
public static void main(String[] args) {
//普通的HashMap
// Map<String,String> map=mapTest.getHashMap();
// map.put("a", "1");
// map.put("b", "1");
// map.put("c", "e");
// System.out.println(map.toString());
// Map<String,String> map1=mapTest.getHashMap();
// System.out.println("-----"+map1.get("a"));
//上锁的HashMap
// Map<String,String> sMap=Collections.synchronizedMap(new HashMap());
// getMap1();
test1();
test2();
}
private static void test1() {
Map<String, String> map = new HashMap<String, String>();
map.put("1", "value1");
map.put("2", "value2");
map.put("3", "value3");
//第一种：普遍使用，二次取值
System.out.println("通过Map.keySet遍历key和value：");
for (String key : map.keySet()) {
System.out.println("key= "+ key + " and value= " + map.get(key));
}
//第二种 使用迭代器Iterator进行遍历
System.out.println("通过Map.entrySet使用iterator遍历key和value：");
Iterator<Map.Entry<String, String>> it = map.entrySet().iterator();
while (it.hasNext()) {
Map.Entry<String, String> entry = it.next();
System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
}
//第三种：使用entrySet遍历 推荐，尤其是容量大时
System.out.println("通过Map.entrySet遍历key和value");
for (Map.Entry<String, String> entry : map.entrySet()) {
System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
}
}
private static void test2() {
Map<String,Object> hashMap=new HashMap<String,Object>();
hashMap.put("a", 1);
hashMap.put("c", 3);
hashMap.put("b", 2);
System.out.println("HashMap:"+hashMap);
Map<String,Object> treeMap=new TreeMap<String,Object>();
treeMap.put("a", 1);
treeMap.put("c", 3);
treeMap.put("b", 2);
System.out.println("TreeMap:"+treeMap);
}
@SuppressWarnings("unused")
private static void getMap1(){
Map<Integer,Integer> map1 =new HashMap<Integer,Integer>();
Map<Integer,Integer> map2 =new HashMap<Integer,Integer>();
map1.put(1, 1);
map1.put(2, 2);
map1.put(3, 3);
map2.put(11, 11);
map2.put(22, 22);
map2.put(33, 33);
Map<Integer,Map<Integer,Integer>> map3 =new HashMap<Integer,Map<Integer,Integer>>();
map3.put(1, map1);
map3.put(2, map2);
System.out.println("map3:"+map3);
StringBuffer sb=new StringBuffer();
for(Entry<Integer,Map<Integer,Integer>> entry:map3.entrySet()){
sb.append(entry.getKey());
sb.append(":");
Map<Integer,Integer> map4=entry.getValue();
for(Entry<Integer,Integer> entry1:map4.entrySet()){
sb.append(entry1.getKey());
sb.append("_");
sb.append(entry1.getValue());
sb.append(",");
}
}
sb.deleteCharAt(sb.lastIndexOf(","));
System.out.println("sb:"+sb);
}
}

33
src/main/java/com/pancm/code/MapCodeTest.java Normal file
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@@ -0,0 +1,33 @@
package com.pancm.code;
import java.util.HashMap;
import java.util.Map;
/**
* @Title: MapCodeTest
* @Description: Map源码学习相关类
* @Version:1.0.0
* @author pancm
* @date 2018年11月29日
*/
public class MapCodeTest {
/**
* @param args
*/
public static void main(String[] args) {
test1();
}
/**
*
*/
private static void test1() {
Map<String, Object> map =new HashMap<>();
map.put("1", 1);
map.put("2", 2);
}
}

8
src/main/java/com/pancm/code/package-info.java Normal file
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@@ -0,0 +1,8 @@
/**
* @Title: package-info
* @Description: 源码相关类
* @Version:1.0.0
* @author pancm
* @date 2018年11月29日
*/
package com.pancm.code;