/**
* 遍历Map的四种方法
*/
public static void method01(){
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
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: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());
}
//第四种
System.out.println("通过Map.values()遍历所有的value,但不能遍历key");
for (String v : map.values()) {
System.out.println("value= " + v);
}
}
//自己遍历方法
public static void method03(){
Map<string, string=""> map = new HashMap<string, string="">();
map.put("1", "value1");
map.put("2", "value2");
map.put("3", "value3");
Iterator it = map.keySet().iterator();
/* String key="";
String value="";
while(it.hasNext()){
key = (String) it.next();
value = map.get(key);
System.out.println(key+":"+value);
} */
}
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原标题:java中遍历Map的4种方法
关键词:JAVA