ObjUtil.java

package com.arialyy.frame.util;

import java.util.Map;
import java.util.Set;

/**
 * Created by lyy on 2016/7/6.
 */
public class ObjUtil {

    /**
     * 打印Map
     */
    public static String getMapString(Map map) {
        Set set = map.keySet();
        if (set.size() < 1) {
            return "[]";
        }
        StringBuilder strBuilder = new StringBuilder();
        Object[]      array      = set.toArray();
        strBuilder.append("[").append(array[0]).append("=").append(map.get(array[0]));
        for (int i = 1; i < array.length; ++i) {
            strBuilder.append(", ");
            strBuilder.append(array[i]).append("=");
            strBuilder.append(map.get(array[i]));
        }
        strBuilder.append("]");
        return strBuilder.toString();
    }

    /**
     * 通过Value 获取key
     *
     * @param map
     * @param value
     * @return
     */
    public static <T, E> T getKeyByValue(Map<T, E> map, E value) {
        for (Map.Entry<T, E> entry : map.entrySet()) {
            if (equals(value, entry.getValue())) {
                return entry.getKey();
            }
        }
        return null;
    }

    /**
     * 比较两个对象是否相等
     *
     * @param a
     * @param b
     * @return
     */
    public static boolean equals(Object a, Object b) {
        return (a == null) ? (b == null) : a.equals(b);
    }
}