WAP to Reverse String Without Affecting Digits Position

WAP to Reverse String Without Affecting Digits Position: In this program InterviewPrograms48, we are reversing the non-numeric substrings within a given string while leaving the numeric substrings unchanged.

Reverse String Without Affecting Digits Position

package com.softwaretestingo.interviewprograms;
public class InterviewPrograms48 
	 * Input string : test986java656hello 
	 * Output : tset986avaj656olleh
	public static void main(String[] args) 
		String str="test986java656hello";
	public static void disp(String str)
		String[] strarr=str.split("(?<=\\D)(?=\\d)|(?<=\\d)(?=\\D)");
		for (int i=0;i<strarr.length;i++)
			if(! Character.isDigit(strarr[i].charAt(0)))

		String s2=String.join("", strarr);

	public static String rev(String str) 
		String rev="";
		for(int i=str.length()-1;i>=0;i--)
		return rev;



Here’s a step-by-step explanation of the program:

  1. public static void main(String[] args): This is the entry point of the program. It starts by defining the input string “test986java656hello”.
  2. disp(str): The program calls the disp method and passes the input string as an argument.
  3. String[] strarr = str.split(“(?<=\\D)(?=\\d)|(?<=\\d)(?=\\D)”);: The input string is split into an array of substrings using regular expressions. The regular expression (?<=\\D)(?=\\d)|(?<=\\d)(?=\\D) matches the boundary between a non-digit and a digit, or the boundary between a digit and a non-digit. This splits the string into segments of continuous non-digits and digits.
  4. for (int i = 0; i < strarr.length; i++): The program iterates through each segment in the strarr array.
  5. if (!Character.isDigit(strarr[i].charAt(0))): If the first character of the segment is a non-digit, the program enters the if condition.
  6. strarr[i] = rev(strarr[i]);: The program calls the rev method and passes the segment as an argument. The rev method reverses the characters in the segment.
  7. String s2 = String.join(“”, strarr);: The program joins the modified segments back into a single string, using an empty string as the delimiter.
  8. System.out.println(s2);: The program prints the resulting string, which is the input string with non-digit segments reversed.

By the end of the program, the output is obtained as “tset986avaj656olleh”, where the non-digit segments in the input string are reversed while the digit segments remain unchanged.

I love open-source technologies and am very passionate about software development. I like to share my knowledge with others, especially on technology that's why I have given all the examples as simple as possible to understand for beginners. All the code posted on my blog is developed, compiled, and tested in my development environment. If you find any mistakes or bugs, Please drop an email to softwaretestingo.com@gmail.com, or You can join me on Linkedin.

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