Java replace all method appending the replacement string instead of replacing - regex

Question

I am trying to replace all the words starting with vowels to "XXXXX" in my text file. I am using RegEx to perform this, but when I try to replace it with replaceAll method, my replacement string is getting appended instead of replacing.
Here is my text file, code and output.
Hello 12 I am John
How are you
I am good
Thank you 89767 0
$%^
code:
String dest = data.replaceAll("\\b(?=[AEIOUaeiou])","XXXXX");
System.out.println(dest);
data is the string that contains all my file data.
output :
Hello 12 XXXXXI XXXXXam Manoj
How XXXXXare you
XXXXXI XXXXXam good
Thank you 89767 0
#$%^
Please help me out in solving this issue. I have gone through some answers regarding replaceAll() method but I am not able to find answer to my problem.

Answer 1

Your pattern only contains zero-width assertions: \\b matches a word boundary location and (?=[AEIOUaeiou]) positive lookahead asserts the position before a vowel.
Make the pattern consuming. Use
data = data.replaceAll("\\b[AEIOUaeiou]\\w*","XXXXX");
To only match letters, replace \w with \p{Alpha}.
See regex demo and a Java demo:
String data = "Hello 12 I am John\nHow are you\nI am good\nThank you 89767 0\n#$%^";
data = data.replaceAll("\\b[AEIOUaeiou]\\p{Alpha}*","XXXXX");
System.out.println(data);
Output:
Hello 12 XXXXX XXXXX John
How XXXXX you
XXXXX XXXXX good
Thank you 89767 0
#$%^