Java 如何创建地图实例变量
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How to create a map instance variable
提问by Harry Jones
I've been trying to create a class that will model a scenario I've come up with. It will involve a map with string keys and values.
我一直在尝试创建一个类来模拟我想出的场景。它将涉及带有字符串键和值的映射。
I need to create an instance variable used to reference the map object, and a constructor that creates the empty map and assigns it to the map instance variable.
我需要创建一个用于引用地图对象的实例变量，以及一个创建空地图并将其分配给地图实例变量的构造函数。
I've been messing around with map objects but not creating a class using them, and I've hit a mental block!
我一直在处理地图对象，但没有使用它们创建一个类，我遇到了心理障碍！
What's the proper way to actually get a map object?
实际获取地图对象的正确方法是什么？
采纳答案by rogue-one
public class TheClass {
private Map<String, String> theMap;
public TheClass() {
theMap = new HashMap<>();
}
}
回答by rogue-one
You can use the HashMap which is an implementation of Map http://docs.oracle.com/javase/7/docs/api/java/util/HashMap.html
您可以使用 HashMap，它是 Map http://docs.oracle.com/javase/7/docs/api/java/util/HashMap.html
Map<String,String> map = new HashMap<String,String>();
map.put("key1", "Value1");
map.put("Key2", "Value2");
回答by Jakub H
If you want to use HashMap which is Map implementation you can do it like that:
如果你想使用 HashMap 这是 Map 实现，你可以这样做：
Map<String, String> map = new HashMap<String, String>();
or
或者
Map<String, String> map = new HashMap<>();
in Java 7.
在 Java 7 中。
You can also use other implementations like TreeMap.
您还可以使用其他实现，例如 TreeMap。
回答by Kick
public class Demo {
Map<String,String> map = null;
public Demo()
{
map = new HashMap<String,String>();
}
}
