The CustomString class also has a “remove” method which returns a new string version of the current string where the alphabetical * characters specified in the given arg, are removed.  For CustomString "my lucky numbers are 6, 8, and 19.", calling remove("ra6") * will return "my lucky numbes e 6, 8, nd 19.".

package customstring;

import static org.junit.jupiter.api.Assertions.assertEquals;

import java.util.*; 

/**
* In this assignment, you will implement a simple class called CustomString.  This class represents a more customizable version
* of a String, with additional attributes and methods. 
* For example, the CustomString class has a “reverse” method
* capitalization is reversed (i.e., lowercase to uppercase and uppercase to lowercase) for the alphabetical characters specified
* in the given arg.  For CustomString “abc, XYZ; 123.”, calling reverse("bcdxyz@3210.") will return "aBC, xyz; 123.". 
*
* The CustomString class also has a “remove” method which returns a new string version of the current string where the alphabetical
* characters specified in the given arg, are removed.  For CustomString "my lucky numbers are 6, 8, and 19.", calling remove("ra6")
* will return "my lucky numbes e 6, 8, nd 19.".
*
*/
public class CustomString {

//instance variables

/**
* Current string.
*/
String myString;

/**
* Indicates if the current string myString has been set (not null).
*/
boolean isSet;

//constructor

/**
* Initializes current string myString to null.
* Initializes isSet to false.
*/
public CustomString() {
// TODO Implement constructor
}

// methods

    /**
     * Returns the current string.
     * If the current string is null, or has not been set to a value with setString, it should return null.
     * @return current string
     */
public String getString() {
// TODO Implement method

return null;
}

/**
     * Sets the value of the current string and sets this.isSet to true.
     * If the given string is null, sets this.isSet to false.
     * @param string value to be set
     */
public void setString(String string) {
// TODO Implement method
}

     * All non-alphabetical characters are unaffected.
     * If the current string is null, empty, or has not been set to a value, this method should return an empty string.
     *
     * Example(s):
     * - For a current string "my lucky numbers are 6, 8, and 19.", calling remove("ra6") would return "my lucky numbes e 6, 8, nd 19."
     * - For a current string "my lucky numbers are 6, 8, and 19.", calling remove("6,.") would return "my lucky numbers are 6, 8, and 19."
     * - For a current string "my lucky numbers are 6, 8, and 19.", calling remove("") would return "my lucky numbers are 6, 8, and 19."
     *
     * Remember: This method builds and returns a new string, and does not directly modify the myString field.
     *
     * @param arg the string containing the alphabetical characters to be removed from the current string
     * @return new string in which the alphabetical characters specified in the arg are removed
     */
public String remove(String arg) {
// TODO Implement method

  return null;
}

/**
* Returns a new string version of the current string where the capitalization is reversed (i.e., lowercase to uppercase,
*  
* All non-alphabetical characters are unaffected.
* If the current string is null, empty, or has not been set to a value, this method should return an empty string.
*
* Example(s):
* - For a current string "abc, XYZ; 123.", calling reverse("bcdxyz@3210.") would return "aBC, xyz; 123."
* - For a current string "abc, XYZ; 123.", calling reverse("6,.") would return "abc, XYZ; 123."
* - For a current string "abc, XYZ; 123.", calling reverse("") would return "abc, XYZ; 123."
* - For a current string "", calling reverse("") would return ""
*
* Remember: This method builds and returns a new string, and does not directly modify the myString field.
*
* @param arg the string containing the alphabetical characters to have their capitalization reversed in the current string
* @return new string in which the alphabetical characters specified in the arg are reversed
*/
public String reverse(String arg) {
// TODO Implement method

return null;
}

    /**
     * Returns a new string version of the current string where all the letters either >= or <= the given char n, are removed. 
     *
     * The given letter may be a-z or A-Z, inclusive.
     * The letters to be removed are case insensitive.
     *
     * If 'more' is false, all letters less than or equal to n will be removed in the returned string.
     * If 'more' is true, all letters greater than or equal to n will be removed in the returned string.
     *
     * If the current string is null, the method should return an empty string.
     * If n is not a letter (and the current string is not null), the method should return an empty string.
     *
     * Example(s) 
     * - For a current string "Abcdefg", calling filterLetters('c', false) would return "defg"
     * - For a current string "Hello 90, bye 2", calling filterLetters('h', true) would return "e 90, be 2
     *
     * @param n char to compare to
     * @param more indicates whether letters <= or >= n will be removed
     * @return new string with letters removed
     */
public String filterLetters(char n, boolean more) {
// TODO Implement method
return null;
}
}