java - String.replaceAll() with [\d]* appends replacement String inbetween characters, why? -

i have been trying hours regex statement match unknown quantity of consecutive numbers. believe [0-9]* or [\d]* should want yet when use java's string.replaceall adds replacement string in places shouldn't matching regex.

for example: have input string of "this my99string problem" if replacement string "~"

when run this

mystring.replaceall("[\\d]*", "~" ) 

or

mystring.replaceall("[0-9]*", "~" ) 

my return string "~t~h~i~s~ ~i~s~ ~m~y~~s~t~r~i~n~g~ ~p~r~o~b~l~e~m~"

as can see numbers have been replaced why appending replacement string in between characters.

i want "this my~string problem"

what doing wrong , why java matching this.

\\d* matches 0 or more digits, , matches empty string. , have empty string before every character in string. so, each of them, replaces ~, hence result.

try using \\d+ instead. , don't need include \\d in character class.