java - Regular Expression to Replace All But One Character In String -

i need regular expression replace matching characters except first 1 in squence in string.

for example;

for matching 'a' , replacing 'b'

for matching ' ' , replacing 'x'

'[space][space][space]a[space][space][space]' should replaced '[space]xxa[space]xx'

you need use regex replacement:

\\ba

\b (between word characters) assert position \b (word boundary) doesn't match
a matches character a literally

java code:

string repl = input.replaceall("\\ba", "b");

update second part of question use regex replacement:

"(?<!^|\\w) "

code:

string repl = input.replaceall("(?<!^|\\w) ", "x");

My