You have a String instance of finite length consisting of only 'a' and 'b's in it. Write the following solution class with the exact target function to separate all of the 'a' and 'b' in the string so that all 'a' appear before 'b' in it:

Required code and output is given below:

Explanation:

import java.util.Scanner;

public class HomworkAssignment3_1

{

  public static void main(String[] args)

  {

      String str;

      Scanner console=new Scanner(System.in);

      System.out.printf("Input: ");

      //read input from user

      str=console.nextLine();  

      //check if length of the string is above 50

      if(str.length()>50)

      {

          System.out.println("Input string size must be less than 50.");

      }

      //check if string is null or empty

      else if(str==null || str.equals(""))

      {

          System.out.println("Input string should not be null or empty.");

      }

      //call method isvalid that takes string,str is not true

      else if(!isvalid(str))

      {

          System.out.println("Input string must contains only a and b letters");

      }

      else

      {

          //create an instance of Solution

          Solution solution=new Solution();

          //call the method,separateLetters

          System.out.println("Output: "+solution.separateLetters(str));

      }      

  }

  /*The method, isvalid that takes string and

  * return true if the str is valid otherwise

  * returns false.*/

  public static boolean isvalid(String str)

  {

      boolean valid=true;

      for (int i = 0; i < str.length() && valid; i++) {

          if(str.charAt(i)!='a' && str.charAt(i)!='b')

              valid=false;

      }

      return valid;

  } //end of the method isvalid

} //end of the class

//Solution.java

public class Solution

{

  /*The method that sorts the */

  public String separateLetters(String input)

  {

      //convert the string to character array

      char ch[]=input.toCharArray();

      //apply sorting algorithm

      for (int outer = 0; outer < input.length(); outer++)

      {

          for (int inner = 0; inner < input.length()-outer-1; inner++)

          {

              if(ch[inner]>ch[inner+1])

              {

                  char temp=ch[inner];

                  ch[inner]=ch[inner+1];

                  ch[inner+1]=temp;

              }

          }  

      }

      //returns the sorted string

      return new String(ch);

  }

}

Sample output:

Run1:

Input: bababa

Output: aaabbb

Run2:

Input: a

Output: