从未给出占位符参数的输出中删除空格

Question

String str = "My name is {0} {1} {2}."

String st = MessageFormat.format(str, "Peter", "", "Maxwell");

基本上，这个印刷品是什么：

My name is Peter (whitespace) Maxwell.

比方说，如果我的字符串有多个占位符并且我传递了一个空白参数，在这种情况下，输出会为该空白参数添加空格。

So, in our previous case, the output should be like:

My name is Peter Maxwell. (No extra whitespace between Peter and Maxwell)

场景 2：

String st = MessageFormat.format(str, "Peter", "Branson", "");

Actual:
**My name is Peter Branson (whitespace).**

Expected:
**My name is Peter Branson.**

What I want to achieve is, for every unsupplied placeholder argument the whitespace should not be part of the final output.

Would appreciate the response !!

Answer 1

您可以使用 正则表达式 将多个白色 space 字符替换为一个字符。喜欢，

String st = MessageFormat.format(str, "Peter", "", "Maxwell")
        .replaceAll("\s+", " ");

或也处理第二种情况

String st = MessageFormat.format(str, "Peter", "", "Maxwell")
        .replaceAll("\s+", " ")
        .replaceAll("\s+\.", ".");

哪些输出（按要求）

My name is Peter Maxwell.

没有其他变化

从未给出占位符参数的输出中删除空格

Remove whitespace from output where placeholder arguments not given

java

string

messageformat