java:Map借口及其子类HashMap二
重点:所有的集合必须依赖Iterator输出
Map<String, Integer> map = new HashMap<String, Integer>();
map.put("zhangsan", 1);
map.put("lisi", 2);
map.put("zhangsan", 3);
map.put("wangwu", 4);
map.put("tianqi", 5);
//获取数据,存放set
//如果用list<string>接受不可用。报错。
Set<String> keys = map.keySet();
Iterator<String> iter = keys.iterator();
//输出
while(iter.hasNext())
{
System.out.print( iter.next() + "、");
}
System.out.println(keys);
结果:
lisi、zhangsan、wangwu、tianqi、
[lisi, zhangsan, wangwu, tianqi]
获取value内容:Map.get(key);
Map<String,Integer> allMap = new HashMap<String, Integer>();
allMap.put("zhangsan", 1);
allMap.put("zhangsan", 2);
allMap.put("lisi", 3);
allMap.put("tianqi", 4);
Integer value = allMap.get("zhangsan");
System.out.println(value);
结果:2
Map<String, Integer> map = new HashMap<String, Integer>();
map.put("zhangsan", 1);
map.put("lisi", 2);
map.put("zhangsan", 3);
map.put("wangwu", 4);
map.put("tianqi", 5);
//获取数据,存放set
//如果用list<string>接受不可用。报错。
Set<String> keys = map.keySet();
Iterator<String> iter = keys.iterator();
//输出
while(iter.hasNext())
{
String key = iter.next();
System.out.println( key + " --> " + map.get(key) + "、");
}
System.out.println(keys);
输出内容:
lisi --> 2、
zhangsan --> 3、
wangwu --> 4、
tianqi --> 5、
[lisi, zhangsan, wangwu, tianqi]