代码如下
/**
*
*
* @author: qiuqiu
**/
public class ListTest {
public static void main(String[] args) {
ArrayList<String> list = new ArrayList<>();
list.add("hello");
list.add("world");
list.add("qiuqiu");
long currentTimeMillis = System.currentTimeMillis();
//1.增强for
for (String s : list) {
System.out.println(s);
}
System.out.println(System.currentTimeMillis() - currentTimeMillis);
//2.迭代器
currentTimeMillis = System.currentTimeMillis();
Iterator<String> iterator = list.iterator();
while (iterator.hasNext()){
String next = iterator.next();
System.out.println(next);
}
System.out.println(System.currentTimeMillis() - currentTimeMillis);
//3.toArray(),转换为数组
currentTimeMillis = System.currentTimeMillis();
Object[] array = list.toArray();
for (int i = 0; i < array.length; i++) {
System.out.println(array[i]);
}
System.out.println(System.currentTimeMillis() - currentTimeMillis);
//4.for 循环,get方法
currentTimeMillis = System.currentTimeMillis();
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i));
}
System.out.println(System.currentTimeMillis() - currentTimeMillis);
}
}
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