Java Map的四种遍历方式

package com.heihaier.map;import com.google.common.collect.ImmutableMap;import java.util.Collection;import java.util.Map;import java.util.Set;/** * Java map 的四种遍历方式 * <p> * User: heihaier * Date: 2015/8/14 * Time: 17:13 */public class MapIterator {    private static final Map<Integer, String> map = ImmutableMap.of(1, "redis", 2, "mongodb", 3, "mysql");    public static void main(String[] args) {        workNormal();        workByKeySet();        workByValues();        workByEntrySet();    }    /**'     * 正常遍历     */    public static void workNormal() {        map.forEach((key, val) -> System.out.println(key + " --- " + val));    }    /**     * 根据key遍历     */    public static void workByKeySet() {        Set<Integer> keySet = map.keySet();        keySet.forEach((key) -> System.out.println(map.get(key)));    }    /**     * 根据values遍历     */    public static void workByValues() {        Collection<String> values = map.values();        values.forEach((val) -> System.out.println(val));    }    /**     * 根据entry遍历     */    public static void workByEntrySet() {        Set<Map.Entry<Integer, String>> entrySet = map.entrySet();        entrySet.forEach((entry) -> System.out.println(entry.getKey() + "---" + entry.getValue()));    }}