Remove selected new line in java string and maintain the String order

Question

I want to remove the new line from the given string format

     This is test;
 
 
 
 This is new test;
 
 
 
 
 This is new test2;
 
 This is another string test;
 
 
 
 
 
 
 
 
 this is more space string test; 

Output should be like this:

 This is test;
 This is new test;
 This is new test2;
 This is another string test;
 this is more space string test; 

I know I can use regex expression or replace all with "\n" but in that case, all the string will be replaced in single line and the order of string which i want won't be maintained.?

Answer 1

One option would be to do a regex replacement on the following pattern, in dot all mode:

\r?\n\s*

Then, just replace with a newline, to retain an original single newline.

String input = "Line 1\r\n\n\n\n     Line 2 blah blah blah\r\n\r\n\n   Line 3 the end.";
System.out.println("Before:\n" + input + "\n");
input = input.replaceAll("(?s)\r?\n\\s*", "\n");
System.out.println("After:\n" + input);

This prints:

Before:
Line 1



 Line 2 blah blah blah


   Line 3 the end.

After:
Line 1
Line 2 blah blah blah
Line 3 the end.