java拼接逗号的四种方式

1.使用String.join　　

        List list = new ArrayList<>(Arrays.asList("1","2","3","4","5"));
        String result = String.join(",",list);
        System.out.println(result);

2.使用stream

        List list = new ArrayList<>(Arrays.asList("1","2","3","4","5"));        
        String result2 = list.stream().collect(Collectors.joining(","));
        System.out.println(result2);    

3.使用StringBuffer

        StringBuffer sb = new StringBuffer();
        for(String str : list){
            sb.append(str).append(",");
        }
        String result3 = sb.toString().substring(0,sb.length()-1);
        System.out.println(result3);

4.使用for

        List list = new ArrayList<>(Arrays.asList("1","2","3","4","5"));
        String result4 = "";
        for(int i = 0;i < list.size();i++){
            if(i == list.size() - 1){
                result4 += list.get(i);
            }else{
                result4 += list.get(i) + ",";
            }
        }
        System.out.println(result4);