import java.util.*;
 
class Ideone {
   public static void main(String[] args) {
String multiLineText = "\tHello        World!" + "\n"        
  + "New line";
 
String lineSeparatorRegex = "\r?\n"; // usually "\n" on Linux/Mac or "\r\n" on Windows
 
List<String> condensedLines = new ArrayList();
String[] lines = multiLineText.split(System.lineSeparator()); // alternative: use the regex 
for (String line : lines) {
  condensedLines.add(line.replaceAll("\\s+", " ")); // condense
}
String condensedPerLine = String.join(System.lineSeparator(), condensedLines);
System.out.println(condensedPerLine);
    }
}
 

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