用于Dictionary的Foreach循环 [英] Foreach loop in java for Dictionary

问题描述

我想通过java中的字典中的每个项目。澄清我要做什么，这是C＃代码

 字典< string，Label> LableList = new Dictionary< string，Label>（）; 
 foreach（LabelValuePair< string，Label> z在LabelList中）; 
  

我不知道如何做这个是java，例如我这样做

  for（Object z：dic）
  

但它说这不是可迭代的。请指教......

解决方案

我假设你有一个 Map< String，标签> 这是Java内置的字典结构。 Java不允许你直接迭代一个 Map （即它不实现 Iterable ），因为它将

这只是一个选择迭代键，值或条目（两者）的问题。

例如

  Map< String，Label> map = new HashMap< String，Label>（）; 
 // ... 
 
 for（String key：map.keySet（））{
} 
 
 for（Label value：map.values （））{
} 
 
 for（Map.Entry< String，Label>条目：map.entrySet（））{
 String key = entry.getKey（）; 
标签值= entry.getValue（）; 
} 
  

您的C＃代码似乎与迭代条目相同（最后一个例如）

I want to go through every items in a dictionary in java. to clarify what I want to do, this is the C# code

Dictionary<string, Label> LableList = new Dictionary<string, Label>();
foreach (KeyValuePair<string, Label> z in LabelList);

I don't know how to do this is java, for example I did this

for(Object z: dic)

but it says it's not iterable. Please advise......

解决方案

I'm assuming you have a Map<String, Label> which is the Java built-in dictionary structure. Java doesn't let you iterate directly over a Map (i.e. it doesn't implement Iterable) because it would be ambiguous what you're actually iterating over.

It's just a matter of choosing to iterate through the keys, values or entries (both).

e.g.

Map<String, Label> map = new HashMap<String, Label>();
//...

for ( String key : map.keySet() ) {
}

for ( Label value : map.values() ) {
}

for ( Map.Entry<String, Label> entry : map.entrySet() ) {
    String key = entry.getKey();
    Label value = entry.getValue();
}

Your C# code seems to be the same as iterating over the entries (the last example).

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