blocks|key|574628|text|您必须遍历并访问每个对象的getName()。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|574629|也许guava可以做些花哨的事。|574630|entityMap|0|LINK|mutability|MUTABLE|url|http://guava-libraries.googlecode.com/svn/trunk/javadoc/com/google/common/base/Function.html^0|D|9|0|2|5|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|S|8|@]|D|@$9|T|A|U|1|V]]|E|$]]|$1|H|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|I|$J|$5|K|L|M|E|$N|O]]]]

You will have to loop through and access each objects <code>getName()</code>. 

Maybe <a href="http://guava-libraries.googlecode.com/svn/trunk/javadoc/com/google/common/base/Function.html" rel="nofollow">guava</a> can do something fancy ...

blocks|key|790793|text|在Java中，除了您建议的方法之外，没有其他方法可以做到这一点，至少只要您坚持使用标准的Java+Collection+API。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|790794|我很久以前就想要这样的东西……尤其是因为我尝到了Ruby的甜蜜自由，它有一些奇妙的东西，比如collect和select，可以处理闭包。|790795|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

There is no other way to do this in Java than the one you suggested, at least as long as you are sticking with the standard Java Collection API.

I have been wishing for something like this for a long time... Especially since I tasted the sweet freedom of Ruby, which has wonderful things like collect and select working with closures.

blocks|key|574723|text|看看http://code.google.com/p/lambdaj/+--有相当于Java的LINQ。使用它不会避免遍历所有项目，但代码会更压缩。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|574724|entityMap|0|LINK|mutability|MUTABLE|url|http://code.google.com/p/lambdaj/^0|2|X|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

take a look at <a href="http://code.google.com/p/lambdaj/" rel="nofollow">http://code.google.com/p/lambdaj/</a> - there is LINQ equivalent for Java. Using it won't avoid iterating all over items but the code would be more compressed.

blocks|key|574763|text|我认为你总是需要这样做。但是如果您总是需要这样的东西，那么我建议创建另一个类，例如，将其命名为People，其中personList是一个变量。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|574764|如下所示：|574765|class+People{
++++List<Person>+personList;
++++//Getters+and+Setters

++++//Special+getters
++++public+List<string>+getPeopleNames(){
+++++++++//implement+your+method+here++++++++
++++}

++++public+List<Long>+getPeopleAges(){
+++++++++//get+all+people+ages+here
++++}
}|code-block|syntax|javascript|574766|在这种情况下，每次只需要调用一个getter。|574767|entityMap^0|1B|6|1K|A|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|V|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|W|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|X|8|@]|D|@]|E|$]]|$1|O|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|P|$]]

I think you will always need to do that. But if you will always need such things, then I would suggest to make another class, for example call it <code>People</code> where <code>personList</code> is a variable.

Something like this:

<pre><code>class People{
 List&lt;Person&gt; personList;
 //Getters and Setters

 //Special getters
 public List&lt;string&gt; getPeopleNames(){
 //implement your method here 
 }

 public List&lt;Long&gt; getPeopleAges(){
 //get all people ages here
 }
}
</code></pre>

In this case you will need to call one getter only each time.

blocks|key|574808|text|没有经过测试，但这是我们的想法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|574809|public+static+<T,+Q>+List<T>+getAttributeList(List+list,+Class<?+extends+Q>+clazz,+String++attribute)++++
{
++++List<T>+attrList=+new+ArrayList<T>();

++++attribute+=+attribute.charAt(0).toUpperCase()+%2B+attribute.substring(1);+
++++String+methodName+=+"get"%2Battribute;

++++for(Object+obj:+personList){
++++++++T+aux+=+(T)clazz.getDeclaredMethod(methodName,+new+Class[0]).invoke(obj,+new+Object[0]);
++++++++attrList.add(aux);
++++}
}|code-block|syntax|javascript|574810|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Not tested but this is the idea:

<pre><code>public static &lt;T, Q&gt; List&lt;T&gt; getAttributeList(List list, Class&lt;? extends Q&gt; clazz, String attribute) 
{
 List&lt;T&gt; attrList= new ArrayList&lt;T&gt;();

 attribute = attribute.charAt(0).toUpperCase() + attribute.substring(1); 
 String methodName = "get"+attribute;

 for(Object obj: personList){
 T aux = (T)clazz.getDeclaredMethod(methodName, new Class[0]).invoke(obj, new Object[0]);
 attrList.add(aux);
 }
}
</code></pre>

blocks|key|574827|text|尝尝这个|type|unstyled|depth|inlineStyleRanges|entityRanges|data|574828|Collection<String>+names+=+CollectionUtils.collect(personList,+TransformerUtils.invokerTransformer("getName"));++|code-block|syntax|javascript|574829|使用apache+commons集合api。|574830|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Try this

<pre><code>Collection&lt;String&gt; names = CollectionUtils.collect(personList, TransformerUtils.invokerTransformer("getName")); 
</code></pre>

Use apache commons collection api.

blocks|key|574858|text|要不是为了别人，你可能已经这么做了。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|574859|使用Java+1.8|574860|List<String>+namesList+=+personList.stream().map(p+->+p.getName()).collect(Collectors.toList());+|code-block|syntax|javascript|574861|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

You might have done this but for others

using Java 1.8

<pre><code>List&lt;String&gt; namesList = personList.stream().map(p -&gt; p.getName()).collect(Collectors.toList()); 
</code></pre>

When there is an <code>List&lt;Person&gt;</code>, is there a possibility of getting List of all <code>person.getName()</code> out of that?
Is there an prepared call for that, or do I have to write an foreach loop like:

<pre><code>List&lt;Person&gt; personList = new ArrayList&lt;Person&gt;();
List&lt;String&gt; namesList = new ArrayList&lt;String&gt;();
for(Person person : personList){
 namesList.add(personList.getName());
}
</code></pre>

Get list of attributes of an object in an List

Java

当存在List<Person>时，是否有可能从中获取所有person.getName()的列表？有没有准备好的调用，或者我必须编写一个foreach循环，如下所示：List<Person> personList = new ArrayList<Person>();List<String> namesList = new...

问获取列表中对象的属性列表
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