Java基础增强---增强for循环实例

eg：

package cn.itcast.demo; import java.util.ArrayList; import java.util.HashMap; import java.util.Iterator; import java.util.LinkedHashMap; import java.util.List; import java.util.Map; import java.util.Map.Entry; import java.util.Set; import org.junit.Test; public class Demo3 { // 增强for @Test public void test1() { int arr[] = { 1, 2, 3, 4 }; for (int num : arr) { System.out.println(num); } } @Test public void test2() { List list = new ArrayList(); list.add(1); list.add(2); list.add(3); for (Object obj : list) { int i = (Integer) obj; System.out.println(i); } } @Test public void test3() { // Map map = new HashMap(); // LinkedHashMap是按顺序的 Map map = new LinkedHashMap(); map.put("1", "aaa"); map.put("2", "bbb"); map.put("3", "ccc"); // 传统Map取值方式1 Set set = map.keySet(); Iterator it = set.iterator(); while (it.hasNext()) { String key = (String) it.next(); String value = (String) map.get(key); System.out.println(key + "=" + value); } } @Test public void test4() { // Map map = new HashMap(); // LinkedHashMap是按顺序的 Map map = new LinkedHashMap(); map.put("1", "aaa"); map.put("2", "bbb"); map.put("3", "ccc"); // 传统Map取值方式2 Set set = map.entrySet(); Iterator it = set.iterator(); while (it.hasNext()) { Map.Entry entry = (Entry) it.next(); String key = (String) entry.getKey(); String value = (String) entry.getValue(); System.out.println(key + "=" + value); } } @Test public void test5() { // Map map = new HashMap(); // LinkedHashMap是按顺序的 Map map = new LinkedHashMap(); map.put("1", "aaa"); map.put("2", "bbb"); map.put("3", "ccc"); // 增强for取map值方式1 for (Object obj : map.keySet()) { String key = (String) obj; String value = (String) map.get(key); System.out.println(key + "=" + value); } } @Test public void test6() { // Map map = new HashMap(); // LinkedHashMap是按顺序的 Map map = new LinkedHashMap(); map.put("1", "aaa"); map.put("2", "bbb"); map.put("3", "ccc"); // 增强for取map值方式2 for (Object obj : map.entrySet()) { Map.Entry entry = (Entry) obj; String key = (String) entry.getKey(); String value = (String) entry.getValue(); System.out.println(key + "=" + value); } } }

分析：

给方法注释@Test，通过Run as Junit来运行单个方法