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

All String functions

replace() replaceFirst() startsWith() getChars() Java - Tutorials

Java

Subhendu Mohapatra

Author & Instructor at plus2net

I write and maintain practical tutorials on Python, PHP, SQL, JavaScript, HTML, jQuery, and web development at plus2net. The tutorials focus on clear explanations, working examples, and code that readers can test and adapt while learning.

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Subhendu Mohapatra