在这种情况下，如果你想要最快的方法，那么for循环会更好。

迭代器运行10,000次的样本量需要40毫秒，而for循环需要2毫秒

        ArrayList<String> alist = new ArrayList<String>();  
        long start, end;  

        for (int i = 0; i < 1000000; i++) {  
            alist.add(String.valueOf(i));  
        }  

        ListIterator<String> it = alist.listIterator();      

        start = System.currentTimeMillis();  
        while (it.hasNext()) {  
            String s = it.next();  
        }  
        end = System.currentTimeMillis();  

        System.out.println("Iterator start: " + start + ", end: " + end + ", delta: "  
            + (end - start));  
        start = System.currentTimeMillis();  
        int ixx = 0;  
        for (int i = 0; i < 100000; i++) {  
            String s = alist.get(i);  
        }  

        System.out.println(ixx);  
        end = System.currentTimeMillis();  
        System.out.println("for loop start: " + start + ", end: " + end + ", delta: "  
            + (end - start));  

这是假设列表中包含字符串。

在没有外部依赖的情况下，这里有一个使用Streams和java 16 toList()的一行程序。

给定迭代器<?>迭代器:

List<?> list = StreamSupport.stream(Spliterators.spliteratorUnknownSize(iterator, 0), false).toList();

在这种情况下，如果你想要最快的方法，那么for循环会更好。

迭代器运行10,000次的样本量需要40毫秒，而for循环需要2毫秒

        ArrayList<String> alist = new ArrayList<String>();  
        long start, end;  

        for (int i = 0; i < 1000000; i++) {  
            alist.add(String.valueOf(i));  
        }  

        ListIterator<String> it = alist.listIterator();      

        start = System.currentTimeMillis();  
        while (it.hasNext()) {  
            String s = it.next();  
        }  
        end = System.currentTimeMillis();  

        System.out.println("Iterator start: " + start + ", end: " + end + ", delta: "  
            + (end - start));  
        start = System.currentTimeMillis();  
        int ixx = 0;  
        for (int i = 0; i < 100000; i++) {  
            String s = alist.get(i);  
        }  

        System.out.println(ixx);  
        end = System.currentTimeMillis();  
        System.out.println("for loop start: " + start + ", end: " + end + ", delta: "  
            + (end - start));  

这是假设列表中包含字符串。

List result = new ArrayList();
while (i.hasNext()){
    result.add(i.next());
}

用谷歌番石榴!

Iterable<String> fieldsIterable = ...
List<String> fields = Lists.newArrayList(fieldsIterable);

++

最好使用像Guava这样的库:

import com.google.common.collect.Lists;

Iterator<Element> myIterator = ... //some iterator
List<Element> myList = Lists.newArrayList(myIterator);

另一个番石榴的例子:

ImmutableList.copyOf(myIterator);

或Apache Commons Collections:

import org.apache.commons.collections.IteratorUtils;

Iterator<Element> myIterator = ...//some iterator

List<Element> myList = IteratorUtils.toList(myIterator);