Map是一个用于存储 Key-Value 键值对的集合类,也就是一组键值对的映射,在Java中Map是一个接口,是和Collection接口同一等级的集合根接口; 存储结构 上图看起来像是数据库中的关系表,有类似的两个字段,KeySet(键的集合)和 Values(值的集合),每一个键值对都是一个Entry; 特点 没有重复的 key; key 用set保存...
import java.util.HashMap; public class Main { public static void main(String[] args) { HashMap<String, String> capitalCities = new HashMap<String, String>(); capitalCities.put("England", "London"); capitalCities.put("Germany", "Berlin"); capitalCities.put("Norway", "Oslo"); capital...
Method Detail isEmpty public boolean isEmpty() Returnstrueif this map contains no key-value mappings. Specified by: isEmptyin interfaceMap<K,V> Overrides: isEmptyin classAbstractMap<K,V> Returns: trueif this map contains no key-value mappings ...
importjava.util.HashMap;// import the HashMap classHashMap<String,String>capitalCities=newHashMap<String,String>(); Add Items TheHashMapclass has many useful methods. For example, to add items to it, use theput()method: Example // Import the HashMap classimportjava.util.HashMap;publicclas...
Java.Util Assembly: Mono.Android.dll Returns aSetview of the mappings contained in this map. C# [Android.Runtime.Register("entrySet","()Ljava/util/Set;","GetEntrySetHandler")]publicoverrideSystem.Collections.ICollectionEntrySet(); Returns
ForEach Method Reference Feedback Definition Namespace: Java.Util.Concurrent Assembly: Mono.Android.dll Overloads 展開資料表 ForEach(Int64, IBiFunction, IConsumer) Performs the given action for each non-null transformation of each (key, value). ForEach(Int64, IBiConsumer) Performs the ...
The iterators returned by all of this class's "collection view methods" arefail-fast: if the map is structurally modified at any time after the iterator is created, in any way except through the iterator's ownremovemethod, the iterator will throw aConcurrentModificationException. Thus, in the...
clearin interfaceMap<K,V> Overrides: clearin classHashMap<K,V> removeEldestEntry protected boolean removeEldestEntry(Map.Entry<K,V> eldest) Returnstrueif this map should remove its eldest entry. This method is invoked byputandputAllafter inserting a new entry into the map. It provides the impl...
(0, null, value, 0);return null;}/*** Adds a new entry with the specified key, value and hash code to* the specified bucket. It is the responsibility of this* method to resize the table if appropriate.** Subclass overrides this to alter the behavior of put method.*/void addEntry(...
Java.Util.Functions Java.Util.Jar Java.Util.Logging Java.Util.Prefs Java.Util.Regex Java.Util.Streams Java.Util.Zip Javax.Annotation.Processing Javax.Crypto Javax.Crypto.Interfaces Javax.Crypto.Spec Javax.Microedition.Khronos.Egl Javax.Microedition.Khronos.Opengles ...