Develop a Java program that performs two essential string manipulation tasks:

• Convert a given string to lowercase.
• Convert a given string to uppercase.

• Method Signature:

  public static String toLowerCase(String value)
• Description:
  • This method converts the given string into lowercase without using built-in string manipulation methods.

• Method Signature:

  public static String toUpperCase(String value)
• Description:
  • This method converts the given string into uppercase without using built-in string manipulation methods.

• Method Signature:

  public static void main(String[] args)
• Functionality:
  1. Prompt the user to input a string.
  2. Call toLowerCase() to convert the string to lowercase.
  3. Call toUpperCase() to convert the string to uppercase.
  4. Display both the lowercase and uppercase results.

• The program should handle all possible string inputs without restrictions.
• Do not use built-in string manipulation methods such as toLowerCase(), toUpperCase(), substring(), or toCharArray().
• The only allowed method from the String class is length().
• You must use loops (for or while) to iterate through the string and manipulate characters.

A HashMap is an efficient way to store character mappings because:

• It provides O(1) lookup time, making conversions fast.
• It allows us to map uppercase letters (A-Z) to lowercase (a-z) and vice versa.

• In ASCII, uppercase and lowercase letters differ by 32:
  • 'A' (65) → 'a' (97), 'B' (66) → 'b' (98), etc.
  • Lowercase letters (a-z) can be mapped back to uppercase using the same logic.

1. Create Two HashMap Objects

   • lowerMap: Maps uppercase letters (A-Z) to lowercase (a-z).
   • upperMap: Maps lowercase letters (a-z) to uppercase (A-Z).

2. Populate the Maps

   • Iterate through uppercase letters (A-Z), mapping each to its lowercase counterpart.
   • Repeat for lowercase letters (a-z), mapping them to uppercase.

3. Perform the Conversion

   • Iterate through the string, checking each character in the respective map.
   • If a character is found in the map, replace it; otherwise, keep it unchanged.

• If HashMap is not used, the conversion can be done using ASCII arithmetic:
  • If a character is between 'A' and 'Z', add 32 to convert it to lowercase.
  • If a character is between 'a' and 'z', subtract 32 to convert it to uppercase.