List转变为逗号分隔的String(Java7和Java8分别实现)

需求：Arrays.asList("AA", "BB") --> "AA,BB"

In Java 8

采用stream的方式

List strList = Arrays.asList("AA", "BB", "CC");
String newStr = strList.stream().collect(Collectors.joining(","));
System.out.println("Output:" + newStr); // Output:AA,BB,CC

使用String.join()函数，给函数传递一个分隔符合一个迭代器，StringJoiner对象会帮助我们完成所有的事情

String newStr = String.join(",", strList);
System.out.println("Output:" + newStr); // Output:AA,BB,CC

In Java 7

Java 7的实现方法

List strList = Arrays.asList("AA", "BB", "CC");
StringBuilder sb = new StringBuilder();
for (int i = 0; i < strList.size(); i++) {
    if (i != 0) {
        sb.append(",");
    }
    sb.append(strList.get(i));
}
System.out.println("Output:" + sb.toString()); // Output:AA,BB,CC

list和以逗号分割的String相互转换(guava)

import com.alibaba.fastjson.JSON;
import com.google.common.base.Joiner;
import com.google.common.collect.Lists;
import com.google.common.base.Splitter;
        List list = Lists.newArrayList("a","b","c"," ");
        String s = Joiner.on(",").join(list); // 以逗号分割
        System.out.println(s); // a,b,c, 
        Splitter split = Splitter.on(',').trimResults().omitEmptyStrings(); // 去前后空格&&去空string
        List list1 = split.splitToList(s);
        System.out.println(JSON.toJSONString(list1)); // ["a","b","c"]

以上为个人经验，希望能给大家一个参考，也希望大家多多支持脚本之家。