/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		System.out.println("Line1\r\nLine 2\r\nLine 3.".replaceAll("[\r\n]+", "%%"));
		// If leading/trailing space should be also removed
		System.out.println("Line1   \r\nLine 2  \r\nLine 3.".replaceAll("\\s*[\r\n]+\\s*", "%%"));
		//or
		System.out.println("Line1   \r\nLine 2  \r\nLine 3.".replaceAll("[^\\S\r\n]*[\r\n]+[^\\S\r\n]*", "%%"));
		//or
		System.out.println("Line1   \r\nLine 2  \r\nLine 3.".replaceAll("[\\p{Zs}\t]*[\r\n]+[\\p{Zs}\t]*", "%%"));
		//or
		System.out.println("Line1   \r\nLine 2  \r\nLine 3.".replaceAll("[\\s&&[^\n\r]]*[\r\n]+[\\s&&[^\n\r]]*", "%%"));
	}
}

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