泛型的提高代码笔记

package com.lc.fanxing;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.junit.Test;

public class genericTest {

	@Test
	public void test1() {

		List<String> list = new ArrayList<String>();

		list.add("aaa");
		list.add("bbb");
		list.add("ccc");
		list.add("ddd");

		Iterator<String> it = list.iterator();
		while (it.hasNext()) {
			String value = it.next();
			System.out.println(value);
		}

		/*
		 * 使用增强for循环输出
		 */
		for (String s : list) {
			System.out.println(s);
		}
	}

	@Test
	public void test2() {
		Map<Integer, String> map = new HashMap<Integer, String>();
		map.put(1, "aa");
		map.put(2, "bb");
		map.put(3, "cc");
		map.put(4, "dd");

		/*
		 * 传统的keyset entryset
		 */
		Set<Map.Entry<Integer, String>> set = map.entrySet();
		Iterator<Map.Entry<Integer, String>> it = set.iterator();
		while (it.hasNext()) {
			Map.Entry<Integer, String> entry = it.next();
			int key = entry.getKey();
			String value = entry.getValue();

			System.out.println(key + "=" + value);
		}

		/*
		 * 增强for循环
		 */
		for (Map.Entry<Integer, String> entry : map.entrySet()) {
			int key = entry.getKey();
			String value = entry.getValue();

			System.out.println(key + "=" + value);
		}

	}
}