用分隔符连接字符串值以处理空字符串和空字符串? [英] Concatenate string values with delimiter handling null and empty strings?

问题描述

在Java 8中，我有一些String值，并且我想以逗号分隔的有效值列表结尾.如果String为 null或为空，我想忽略它.我知道这似乎很常见，很像

In Java 8 I have some number of String values and I want to end up with a comma delimited list of valid values. If a String is null or empty I want to ignore it. I know this seems common and is a lot like this old question; however, that discussion does not address nulls AND spaces (I also don't like the accepted answer).

我看过Java 8 StringJoiner，Commons StringUtils(join)和可信赖的Guava(Joiner)，但似乎没有一个完整的解决方案.愿景:

I've looked at Java 8 StringJoiner, Commons StringUtils (join) and trusty Guava (Joiner) but none seems like a full solution. The vision:

 where: val1 = "a", val2 = null, val3 = "", val4 = "b"

  String niceString = StringJoiner.use(",").ignoreBlanks().ignoreNulls()
    .add(val1).add(val2).add(val3).add(val4).toString();

...将导致niceString = a,b

...would result in niceString = a,b

有没有一种好方法(不涉及for循环，将字符串加载到列表中和/或使用regex替换来删除不良条目)?

Isn't there a nice way to do this (that doesn't involve for loops, loading strings into a list, and/or regex replaces to remove bad entries)?

推荐答案

String joined = 
    Stream.of(val1, val2, val3, val4)
          .filter(s -> s != null && !s.isEmpty())
          .collect(Collectors.joining(","));

这篇关于用分隔符连接字符串值以处理空字符串和空字符串?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！