创建 HashMap 的不同方法

问题描述

我最近一直在学习 HashMaps，但我有一个问题似乎无法得到明确的答案.主要区别 -

I've been learning about HashMaps recently but I have one question that I can't seem to get a clear answer on. The main difference between -

HashMap hash1 = new HashMap();

对比

HashMap<,>hash1 = new HashMap <,> (); //Filled in with whatever Key and Value you want. 

我认为当您定义 HashMap 时，它需要键和值.任何帮助将非常感激.谢谢.

I thought when you define a HashMap it requires the Key and Value. Any help would be much appreciated. Thank You.

推荐答案

这些是你的选择:

J2SE <5.0 风格:

J2SE <5.0 style:

 Map map = new HashMap();

J2SE 5.0+ 风格(使用泛型):

J2SE 5.0+ style (use of generics):

 Map<KeyType, ValueType> map = new HashMap<KeyType, ValueType>();

Google Guava 样式(更短更灵活):

Google Guava style (shorter and more flexible):

 Map<KeyType, ValueType> map = Maps.newHashMap();

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