Need help with calling methods

I have a driver and a main program.

How would I go along with calling the encode method to the driver class that I made so I can have the user inputs affected by the encode method?

Java Code:

public class ShiftEncoderDecoder
{
   
   private int shift;
   
   public ShiftEncoderDecoder(int shift)
   {
      setShift(shift);
   }
   
   public int getShift()
   {
      return shift;
   }
   private String prepareString(String plainText)
   {
      String preparedString = "";
      for(int i = 0 ; i < plainText.length();i++)
      if(Character.isAlphabetic(plainText.charAt(i)))
      {
         preparedString = preparedString+Character.toUpperCase(plainText.charAt(i));        
      }
      return preparedString;
   }
   public String encode(String plainText)  
   {
      int prepareString;
      int shiftChar;
      String preparedString2 = prepareString(plainText);
      
      String cipherText = ""; 
      for(int c = 0 ; c < preparedString2.length();c++)
      if(Character.isAlphabetic(preparedString2.charAt(c)))
      {   
         cipherText = cipherText+shiftChar(preparedString2.charAt(c),shift); 
      }
      return cipherText; 
   }
   public String decode(String cipherText)
   {
      String decodedText ="";
      for(int z = 0 ; z < cipherText.length();z++)
      if(Character.isAlphabetic(cipherText.charAt(z)))
      {
          decodedText = decodedText+shiftChar(cipherText.charAt(z),-shift);
      }
      return decodedText;
   }   
}

Java Code:

import java.lang.*;
import java.util.*;
import java.util.Scanner; 

public class ShiftEncoderDecoderDriver
{
   public static void main(String[] args)
   {
      Scanner uInput = new Scanner(System.in);
      System.out.print("Please enter the code that you wish to encode...");
      String plainText = uInput.nextLine();
      int shift;
      do
      {
         System.out.println("Please enter the amount of spaces the letters will shift... ");
         shift = uInput.nextInt();
         if(shift <= 25 && shift >= -25)
         {
            System.out.println("The letters will shift "+shift+" places.");
            break;
         }
         else if(shift > 25)
         {
            System.out.println("Your input is larger then how far the letters are allowed to shift, try again.");
         }
         else if(shift < -25)
         {
            System.out.println("Your input is smaller then how far the letters are allowed to shift, try again.");
         }
      }
      while(shift <= 25 || shift >= -25);
      {      
      System.out.println("The input you wish to encode... "+plainText);
      System.out.println("How many spaces the letters will shift... "+shift);
      }
      ShiftEncoderDecoder cipher = new ShiftEncoderDecoder();
      plaintText.encode();
  } 
}