Java 将向量转换为列表
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convert vector to list
提问by sarah
How to convert a vector to a list?
如何将向量转换为列表？
采纳答案by cletus
Vectoris a concrete class that implements the Listinterface so technically it is already a List. You can do this:
Vector是一个实现List接口的具体类，所以从技术上讲它已经是一个List. 你可以这样做：
List list = new Vector();
or:
或者：
List<String> list = new Vector<String>();
(assuming a Vectorof Strings).
（假设 aVector的Strings）。
If however you want to convert it to an ArrayList, which is the closest Listimplementation to a `Vector~ in the Java Collections Framework then just do this:
但是，如果您想将其转换为ArrayList，这是ListJava 集合框架中最接近`Vector~ 的实现，那么只需执行以下操作：
List newList = new ArrayList(vector);
or for a generic version, assuming a Vectorof Strings:
或者对于通用版本，假设 aVector的Strings：
List<String> newList = new ArrayList<String>(vector);
回答by les2
If you want a utility method that converts an generic Vector type to an appropriate ArrayList, you could use the following:
如果您想要一个将通用 Vector 类型转换为适当的 ArrayList 的实用方法，您可以使用以下内容：
public static <T> ArrayList<T> toList(Vector<T> source) {
return new ArrayList<T>(source);
}
In your code, you would use the utility method as follows:
在您的代码中，您将按如下方式使用实用程序方法：
public void myCode() {
List<String> items = toList(someVector);
System.out.println("items => " + items);
}
You can also use the built-in java.util.Collections.list(Enumeration) as follows:
您还可以使用内置的 java.util.Collections.list(Enumeration) 如下：
public void myMethod() {
Vector<String> stringVector = new Vector<String>();
List<String> theList = Collections.list(stringVector.elements());
System.out.println("theList => " + theList);
}
But like someone mentioned below, a Vector is-a List! So why would you need to do this? Perhaps you don't want some code you use to know it's working with a Vector - perhaps it is inappropriately down-casting and you wish to eliminate this code-smell. You could then use
但是就像下面提到的某人一样，Vector is-a List！那么为什么需要这样做呢？也许您不希望您使用的某些代码知道它正在与 Vector 一起工作 - 也许它是不恰当的向下转换，并且您希望消除这种代码味道。然后你可以使用
// the method i give my Vector to can't cast it to Vector
methodThatUsesList( Collections.unmodifiableList(theVector) );
if the List should be modified. An off-the-cuff mutable wrapper is:
如果列表应该被修改。即用型可变包装器是：
public static <T> List<T> asList(final List<T> vector) {
return new AbstractList<T>() {
public E get(int index) { return vector.get(index); }
public int size() { return vector.size(); }
public E set(int index, E element) { return vector.set(index, element); }
public void add(int index, E element) { vector.add(index, element); }
public E remove(int index) { return vector.remove(index); }
}
}
