• 遍历：Stream遍历，循环遍历

//TODO 为Java提供的一种书签import java.util.Vector;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Random;/*** 数组多种遍历偶数方法* * @author 轩**/
public class Main {public static void main(String args[]) {long begin = 0;Random rd = new Random();System.out.print("遍历原数组: ");Vector<Integer> arr = new Vector<Integer>();for (int i = 0; i < 10; i++) {// 插入元素int a = (rd.nextInt() % 100) + 100;arr.add((Integer) (a));System.out.print(a + " ");}System.out.println("\n");/****************************************************************************/System.out.println("第一种：Enumeration接口实现");begin = System.currentTimeMillis();Enumeration<Integer> head;head = arr.elements();// 类似指向数组的头-1；// Enumeration接口提供了遍历Vector和HashTable类型集合元素的功能，类似迭代器Iteratorwhile (head.hasMoreElements()) {// hasMoreElements();方法判断是否还有元素if (head.nextElement() % 2 == 0)System.out.print(head.nextElement() + " ");// nextElement()返回下一个} // whileSystem.out.println("\n 运行时间：" + (System.currentTimeMillis() / 1000f - begin) + "\n");/****************************************************************************/System.out.println("第二种：foreach“只能读取数据");for (int m : arr) {if (m % 2 == 0)System.out.print(m + " ");}System.out.println("\n 运行时间：" + (System.currentTimeMillis() / 1000f - begin) + "\n");/****************************************************************************/System.out.println("第三种：for循环");for (int i = 0; i < arr.size(); i++) {if (arr.get(i) % 2 == 0)System.out.print(arr.get(i) + " ");}System.out.println("\n 运行时间：" + (System.currentTimeMillis() / 1000f - begin) + "\n");/****************************************************************************/System.out.println("第四种：iterator迭代遍历");Iterator<Integer> head_Iterator = arr.iterator();while (head_Iterator.hasNext()) {int a = head_Iterator.next();if (a % 2 == 0)System.out.print(a + " ");}System.out.println("\n 运行时间：" + (System.currentTimeMillis() / 1000f - begin) + "\n");/****************************************************************************/System.out.println("第五种：Consumer,函数式接口lambda");arr.stream().filter(a -> a % 2 == 0)// 过滤.forEach(a -> System.out.print(a + " "));// 遍历System.out.println("\n 运行时间：" + (System.currentTimeMillis() - begin) / 1000f * 1000 + "\n");/****************************************************************************/}// main
}