java实现一个简单的计数器

package com.fengunion.sf;

import org.junit.platform.commons.util.StringUtils;

import java.util.HashMap;import java.util.Map;import java.util.Random;

public class CountUtil {    private static Map<String, Integer> map = null;

static {        map = new HashMap<String, Integer>();    }

/**     *     * 实现一个简单的计数器     * @param str     * @return     */    public static int countNum(String str) {        if (StringUtils.isNotBlank(str)) {            Integer count = map.get(str);            if (count == null) {                count = 1;            } else {                count++;            }            map.put(str, count);        }        return map.get(str);    }

public static void main(String[] args) {

for(int i = 0; i<new Random().nextInt(50); i++){            countNum("a");        }        countNum("a");        countNum("b");        countNum("b");        countNum("c");        int counta = countNum("a");        int countb = countNum("b");        countNum("c");        countNum("c");        int countc = countNum("c");

System.out.println(" countaNum: " + counta + " countbNum: " + countb + " countcNum: " + countc);

}}

原文地址：https://www.cnblogs.com/coderdxj/p/9817477.html