遍歷集合的常見的幾種方法

list遍歷原文地址http: //www.2cto.com/kf/201207/140158.html
/** 
 * 
 */
package com.svse.test;
import java.util. * ;
/**
 * @author seven
 * 
 */
public class ListTest {
	public static void main(String[] args) {
		List l = new ArrayList();
		l.add("世界你好！");
		l.add("上海");
		for (int i = 0; i < l.size(); i++) { // 普通的for循環取出集合中的元素
			System.out.print(l.get(i));
		}
		System.out.println();
		for (Object o: l) { // 增強for循環取出集合中的元素
			System.out.print(o);
		}
		System.out.println();
		for (Iterator it = l.iterator(); it.hasNext();) { // 利用迭代器取出集合中的元素
			System.out.print(it.next());
		}
		System.out.println();
		Iterator it = l.iterator(); // 利用迭代器取出集合中的元素
		while (it.hasNext()) {
			System.out.print(it.next());
		}
	}
}
map遍歷
/**
 * 
 */
package com.svse.test;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
/**
 * @author seven
 * 
 */
public class MapTest1 { // java中遍歷MAP的幾種方法
	public static void main(String[] args) {
		Map < String,
		String > map = new HashMap < String,
		String > ();
		map.put("userID", "1");
		map.put("username", "qq");
		map.put("passWord", "123");
		map.put("email", "[email protected]"); // 第一種用for循環
		for (Map.Entry < String, String > entry: map.entrySet()) {
			System.out.println(entry.getKey() + "=" + entry.getValue());
		} // 第二種用迭代
		Set set = map.entrySet();
		Iterator i = set.iterator();
		while (i.hasNext()) {
			Map.Entry < String,
			String > entry1 = (Map.Entry < String, String > ) i.next();
			System.out.println(entry1.getKey() + "=" + entry1.getValue());
		} // 用keySet()迭代
		Iterator it = map.keySet().iterator();
		while (it.hasNext()) {
			String key;
			String value;
			key = it.next().toString();
			value = map.get(key);
			System.out.println(key + "=" + value);
		} // 用entrySet()迭代
		String key;
		String value;
		while (it.hasNext()) {
			Map.Entry entry = (Map.Entry) it.next();
			key = entry.getKey().toString();
			value = entry.getValue().toString();
			System.out.println(key + "=" + value);
		}
	}
}
		/**
 * 
 */
		package com.svse.test;
		/**
 * @author seven
 *
 */
		import java.util.HashMap;
		import java.util.Iterator;
		import java.util.Map;
		import java.util.Set;
		public class MapTest2 {
			public static void main(String[] args) {
				Map < String,
				String > m = new HashMap < String,
				String > ();
				m.put("sa", "123");
				m.put("sb", "143");
				m.put("sc", "153");
				m.put("sd", "184");
				Set keyset = m.keySet(); // 對Map集合的迭代方法一keyset 迭代
				Iterator it = keyset.iterator();
				while (it.hasNext()) {
					String p = (String) it.next();
					System.out.println("value=" + m.get(p) + " ");
				}
				Iterator it2 = m.entrySet().iterator(); // Map集合的迭代方法二entrySet迭代
				String key;
				String value;
				while (it2.hasNext()) {
					Map.Entry entry = (Map.Entry) it2.next();
					key = entry.getKey().toString();
					value = entry.getValue().toString();
					System.out.println(key + "=" + value + " ");
				}
				for (Map.Entry entry: m.entrySet()) { // // Map集合的迭代方法三for循環迭代
					System.out.println(entry.getKey() + "=" + entry.getValue() + " ");
				}
			}
		}