The difference between replace and ReplaceAll in Java

The parameters of 1>replace are char and charsequence, which can either support character substitution or support string Substitution.  The 2>replaceall parameter is a regex, and Replacement,regex represents a regular Expression. String str = "wel2come3souhe";
String str1 = str.replace ("e", "e");
String STR3 = str.replace (' e ', ' e ');
System.out.println ("replace string = =" + str1);
System.out.println ("replace character = =" +str3);
String str2 = Str.replaceall ("\\d", "a");//replacing A number with a
System.out.println ("replaceall==" + str2); output result: Replace string ==wel2come3souhe
Replace character ==wel2come3souhe
Replaceall==welacomeasouhe comparison results: replace replacement character and string are the same, ReplaceAll is replaced by regular expression

The difference between replace and ReplaceAll in Java