Ask user to input a string. (assume length of input string is 1) If the string is lower case, print its upper case If the string is upper case, print its lower case If the input string is a number, stop program, otherwise repeat it. (In java)

import java.util.*;

import java.util.Scanner;

class Main

{

public static void main(String[] args) {

System.out.println("Enter String");

Scanner sc1=new Scanner(System.in);

String s1= sc1.nextLine();

boolean b= isNumerc(s1);

if (b== true)

{

    System.out.println("Its number: Sorry");

}

else

{

boolean a=isStringUpperCas(s1);

if(a == false)

{

    System.out.println(s1.toUpperCase());

}

else

{

    System.out.println(s1.toLowerCase());

}

}

}

private static boolean isStringUpperCas(String st1){

      char[] arr = st1.toCharArray();

      int k =0; boolean flag=true;

      while(k<arr.length)

      {

          if( Character.isUpperCase( arr[k] ))

          {

              flag=true;

              k++;

          }

          else

          {

              flag=false;

              k++;

          }

      }

      return flag;

}

  public static boolean isNumerc(final String st1) {

      if (st1 == null || st1.length() == 0) {

          return false;

      }

      for (char ch : st1.toCharArray()) {

          if (!Character.isDigit(ch)) {

              return false;

          }

      }

      return true;

  }

}

Explanation:

Please find the program above.