替换所有空格分隔的字符串

Question

I am trying to replace some strings delimited by whitespace. Pattern matching works as expected but at the time of replacement the whitespace is also replaced (like newline in following example) which I want to avoid. This is what I have so far:

String myString = "foo bar,\n"+
                   "is a special string composed of foo bar and\n"+
                   "it is foo bar\n"+
                   "is indeed special!";

String from = "foo bar";
String to = "bar foo";
myString = myString.replaceAll(from + "\\s+", to)

expected output = "foo bar,
                   is a special string composed of bar foo and
                   it is bar foo
                   is indeed special!";


actual output = "foo bar,
                 is a special string composed of bar foo and
                 it is bar foo is indeed special!";

Answer 1

Match and capture the whitespace at the end of the from string, and then use it in the replacement:

String from = "foo bar";
String to = "bar foo";
myString = myString.replaceAll(from + "(\\s+)", to + "$1");
System.out.println(myString);

Note that you could also just use a single string foo bar\\\\s+ for the pattern, but maybe you don't want this, because you want the pattern to be flexible.

Output:

foo bar,
is a special string composed of bar foo and
it is bar foo
is indeed special!