Java String.replaceAll() regular expression string replacement

String.replaceAll() regular expression string replacement .
Here are some examples with output.
Replacing all words starting from m to p

String str = "Welcome to plus2net.com";
System.out.println(str);
System.out.println(str.replaceAll("[m-p]","*"));

Output is here

Welcome to plus2net.com
Welc**e t* *lus2*et.c**

Chars m, n, o, p are replaced with a * in above code.
Let us replace all digits.

String str = "Welcome to plus2net.com";
System.out.println(str);
System.out.println(str.replaceAll("[0-9]","*"));

Output

Welcome to plus*net.com

We can also replace all digits by this code

System.out.println(str.replaceAll("\\d","*"));

Let us match the word boundaries and replace them with *

System.out.println(str.replaceAll("\\b","*"));

Output is here ( note our variable str is same as in above codes, we are not repeating here. )

*Welcome* *to* *plus2net*.*com*

Replace all Non digits present in the string

System.out.println(str.replaceAll("\\D","*"));

Output

***************2*******

Replace all upper case chars only.

String str1 = "Welcome to Plus2Net.com";
System.out.println(str1.replaceAll("\\p{Upper}","*"));

Output

*elcome to *lus2*et.com

string.replaceAll()