Moving all Upper case letters to the end of the String using Java RegEx

The subexpression “[ ]” matches all the characters specified in the braces. Therefore, to move all the upper case letters to the end of a string −

• Iterate through all the characters in the given string.

• Match all the upper case letters in the given string using the regular expression "[A-Z]".

• Concatenate the special characters and the remaining characters to two different strings.

• Finally, concatenate the special characters string to the other string.

Example 1

public class RemovingSpecialCharacters {
   public static void main(String args[]) {
      String input = "sample B text C with G upper case LM characters in between";
      String regex = "[A-Z]";
      String specialChars = "";
      String inputData = "";
      for(int i=0; i< input.length(); i++) {
         char ch = input.charAt(i);
         if(String.valueOf(ch).matches(regex)) {
            specialChars = specialChars + ch;
         } else {
            inputData = inputData + ch;
         }
      }
      System.out.println("Result: "+inputData+specialChars);
   }
}

Output

Result: sample text with upper case characters in betweenBCGLM

Example 2

Following is the Java program which moves the upper case letters of a string to its end using the methods of Regex package.

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Test {
   public static void main(String args[]) {
      String input = "sample B text C with G upper case LM characters in between";
      String regex = "[A-Z]";
      String specialChars = "";
      System.out.println("Input string: \n"+input);
      //Creating a pattern object
      Pattern pattern = Pattern.compile(regex);
      //Matching the compiled pattern in the String
      Matcher matcher = pattern.matcher(input);
      //Creating an empty string buffer
      StringBuffer sb = new StringBuffer();
      while (matcher.find()) {
         specialChars = specialChars+matcher.group();
         matcher.appendReplacement(sb, "");
      }
      matcher.appendTail(sb);
      System.out.println("Result: \n"+ sb.toString()+specialChars );
   }
}

Output

Input string:
sample B text C with G upper case LM characters in between
Result:
sample text with upper case characters in betweenBCGLM