1 Stream流

public static String parseListToStr(List list){

        String result = list.stream().map(String::valueOf).collect(Collectors.joining(","));

        return result;

}

2 使用谷歌Joiner方法

import com.google.common.base.Joiner;

public static String parseListToStr1(List list){

        String result = Joiner.on(",").join(list);

        return result;

}

3 循环插入逗号

public static String parseListToStr2(List list) {

        StringBuffer sb=new StringBuffer();

        if( listIsNotFull ( list ) ){

                for(int i = 0; i < = list.size()-1;i++){

                        sb.append(list.get(i)+",");

                }else{

                        sb.append(list.get(i));

                }

        }

        return sb.toString();

}

4 lambda表达式遍历并加入符号

public static String parseListToStr3(List list){

        StringBuffer sb = new StringBuffer();

        list.stream().forEach(str - > { sb .append(str). append(",");});

        sb.deleteCharAt(sb.length()-1);

        return sb.toString();

}

5 org.apache.commons.lang.StringUtils lang包下面

public static String parseListToStr3(List list){

       String str= StringUtils.join(list,",");

        return str;

}