首页 \ 问答 \ 如何在java中将Map 转换为Map ?(How to convert Map to Map in java?)

如何在java中将Map 转换为Map ?(How to convert Map to Map in java?)

我有类型为Object的Map,我需要将此映射转换为String类型。

Map<String, String> map = new HashMap<String, String>();    
Properties properties = new Properties();    
properties.load(instream);     

可以告诉我,如何将属性分配到上面的地图?

谢谢和问候,Msnaidu


I have the Map of type Object, i need to convert this map into the type String.

Map<String, String> map = new HashMap<String, String>();    
Properties properties = new Properties();    
properties.load(instream);     

Can any body please tell me, how to assign the properties to above map?

Thanks & Regards, Msnaidu


原文:https://stackoverflow.com/questions/17208346
更新时间:2019-12-13 08:36

最满意答案

将属性添加到地图的最简洁方法是(从您的示例开始):

for (String propName : properties.stringPropertyNames()) {
    map.put(propName, properties.getProperty(propName));
}

这在这种特殊情况下很有效,因为Properties对象实际上是一个包含String键和值的映射,因为getProperty方法很清楚。 由于可怕的向后兼容性原因Map<Object, Object>它仅被声明为Map<Object, Object>

通过使用特定于属性的方法,而不是将其视为Map<Object, Object> ,您可以使用完美的类型安全(而不是必须强制转换)填充Map<String, String>


The cleanest way to add the properties to the map would be (following on from your example):

for (String propName : properties.stringPropertyNames()) {
    map.put(propName, properties.getProperty(propName));
}

This works nicely in this particular case, because the Properties object is really a map containing String keys and values, as the getProperty method makes clear. It's only declared as Map<Object, Object> for horrible backwards-compatibility reasons.

By using the Properties-specific methods, rather than treating this as just a Map<Object, Object>, you can populate your Map<String, String> with perfect type-safety (rather than having to cast).

2013-06-20

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