Map常用方法
Map map = new HashMap();
Map iMap = new HashMap();
iMap.put("狂人日记","鲁迅")
map.put("家","巴金");
map.put("朝花夕拾","冰心");
map.put("骆驼祥子","老舍");
map.put("项链","莫泊桑");
map.remove("家")
map.remove("家","巴金")
map.size()
map.clear()
map.isEmpty()
map.get("项链")
map.cotainsKey("家")
map.containsValue("巴金")
Collection set = map.entrySet()
Collection set = map.keySet()
Collection list = map.values()
Entry方法
Collection set = map.entrySet()
set.forEach(entry ->
System.out.println("--->"+obj.getKey())
System.out.println("--->"+obj.getValue())
obj.setValue("佚名")
)
Java8为Map新增的方法
Object compute(Object key,BiFunction remappingFunction)
map.compute("爱的教育",(key,vlaue)->((String)key).length())
object computeIfAbsent(object key, Function remappingFunction)
Object computeIfPresent(object key,BiFunction remappingFunction)
void forEach(BiFunction action)
map.forEach((k,v)-> System.out.println("key:"+k+" value:"+v));
object getOrDefault(object key,V defalutValue)
System.out.println(map.getOrDefault("活着","余华"));
Object merge(object key,object value,BiFunction remappingFunction)
object putIfAbsent(Object key,object value)
object replace(object key,object value)
boolean replace(K key,V oldValue,V newValue)
replaceAll(BiFunction function)
map.replaceAll((k,v)->((String)k).length());
遍历map的方法
for(Object key : map.keySet()){
System.out.printLn(key +"---> "+map.get(key))
}
map.forEach((k,v)-> System.out.println("key:"+k+" value:"+v));