java 將 list 字符串用逗號隔開拼接字符串

第一種：使用谷歌Joiner方法

import com.google.common.base.Joiner;

public static <T> String parseListToStr(List<T> list){
    String result = Joiner.on(",").join(list);
    return result;
}

第二種：循環插入逗號

//java項目www.fhadmin.org
public static <T> String parseListToStr(List<T> list){
    StringBuffer sb = new StringBuffer();
    if(listIsNotNull(list)) {
        for(int i=0;i<=list.size()-1;i++){
            if(i<list.size()-1){
                sb.append(list.get(i) + ",");
            }else {
                sb.append(list.get(i));
            }
        }
    }
    return sb.toString();
}

第三種：stream流

public static <T> String parseListToStr3(List<T> list){
    String result = list.stream().map(String::valueOf).collect(Collectors.joining(","));
    return result;
}

第四種：lambda表達式遍歷並加入逗號

public static <T> String parseListToStr2(List<T> list){
     StringBuffer sb = new StringBuffer();
     list.stream().forEach(str->{
         sb.append(str).append(",");
     });
     sb.deleteCharAt(sb.length()-1);
     return sb.toString();
}