一演示案例

1.1 编写一个对象

package com.ljf.spring.boot.demo.model;/** * @ClassName: Users * @Description: TODO * @Author: liujianfu * @Date: 2021/06/11 19:15:53  * @Version: V1.0 **/public class Users {    private String name;    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }}

1.2 pom文件引入一个拼接字符串工具包


       
         
    
     com.google.guava
          
    
     guava
          
    
     18.0

1.3 造数据

//封装造数据        Users u=new Users();        u.setName("北京");        Users u2=new Users();        u2.setName("上海");        List
   
     datalist=new ArrayList
    
     ();        datalist.add(u);        datalist.add(u2);

1.4 遍历

1.传统遍历

//遍历方式1        StringBuffer sb=new StringBuffer();        for(Users us:datalist){            sb.append(us.getName()+",");        }        //去除末尾逗号        String result=sb.toString();        if(result.endsWith(",")){            result=result.substring(0,result.length()-1);        }        System.out.println("sb:"+result);

2.java8的stream遍历

//遍历方式二        String result2="";        if (datalist!=null && !datalist.isEmpty()){            //java8的stream api            Set
   
     set=datalist.stream().map(Users::getName).collect(Collectors.toSet());            result2= Joiner.on(",").join(set);        }        System.out.println("sb2:"+result2);