如何创建字符串向量Java中的数组？ [英] How to create an array of string vectors in Java?

问题描述

我用下面的code尝试创建的字符串向量的数组，我希望有3个项目的数组，每个项目是一个字符串矢量：

I use the following code try to create an array of string vectors, I hope to have an array of 3 items, each item is a string vector :

Vector<String> Result_Vector_Array[]=new Vector<String>[3];

但NB强调了行错误（通用阵列创建），有什么不对？什么是做了正确的方法是什么？我知道有也ArrayList中，但它不是同步的，所以我想用向量。

But NB highlighted the line as error(generic array creation), what's wrong ? What's the correct way to do it ? I know there is also Arraylist, but it's not synchronized, so I want to use vector.

推荐答案

由于类型消除时，JVM不知道在运行时，你有字符串的矢量。它可以做的最好的是创建一个原始的矢量。它不能保证你所有的矢量 5事实上包含字符串秒。这就是为什么你从​​你的IDE得到一个警告。

Due to type erasure, the JVM doesn't know at runtime that you have a Vector of String. The best it can do is create a 'raw' Vector. It can't guarantee for you that all Vectors actually contain Strings. That's why you get a warning from your IDE.

一个办法来解决这个问题，把它转换它，因为jgubby建议。另一种方法是把列表到矢量 S，而不是数组。

One way to work around this, it cast it, as jgubby suggests. Another is to put a List into your Vectors, instead of an array.

但是，更重要的是，为什么可以在阵列只有3个项目？那岂不是更好地创建一个类有三个字段，把你的矢量？随着三个项目，这不是太多的工作，你会得到额外的奖励，你可以给每个的三个要素一个有用的名称，它应该让你的code更清晰了很多。

But, more importantly, why can the array have only 3 items? Wouldn't it be better to create a class with three fields to put into your Vector? With three items, that's not too much work, and you get the added bonus that you can give each of the three elements a helpful name, which should make your code a lot clearer.

此外，由于Java 6中，存在着许多有用的新同步列表实现，这可能会表现得比矢量，如<一个href=\"http://java.sun.com/javase/6/docs/api/java/util/concurrent/CopyOnWriteArrayList.html\"><$c$c>CopyOnWriteArrayList,或者换一个普通的列表在<一个href=\"http://java.sun.com/javase/6/docs/api/java/util/Collections.html#synchronizedList%28java.util.List%29\"><$c$c>Collections.synchronizedList.

Also, since Java 6, there exist a number of useful new synchronized List implementations, which might perform better than Vector, such as CopyOnWriteArrayList, or wrap a regular List in a Collections.synchronizedList.

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