public static String parseListToStr(List list){
        String result = list.stream().map(String::valueOf).collect(Collectors.joining(","));
        return result;
}

import com.google.common.base.Joiner;
public static String parseListToStr1(List list){
        String result = Joiner.on(",").join(list);
        return result;
}

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();
}

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();
}

public static String parseListToStr3(List list){
       String str= StringUtils.join(list,",");
        return str;
}

 
public static void main(String args[]) {
        String arrayStr="1,2,5,4,1";
        //方式1
        List<Integer> integerList = Arrays.stream(arrayStr.split(",")).map(s -> Integer.valueOf(s.trim())).collect(Collectors.toList());
        //方式2(判空處理,推薦)
        List<Integer> integerList1 = StringUtils.isNotBlank(arrayStr)? Stream.of(arrayStr.split(",")).map(Integer::valueOf).collect(Collectors.toList()): Lists.newArrayList();
        //方式3
//        List<Integer> integerList2 = Arrays.asList((Integer[]) ConvertUtils.convert("1,2".split(","), Integer.class));
        System.out.println(integerList1);
        System.out.println(integerList);
    }