Please help me with this task. Thank you!
public class CustomString {
String myString;
boolean isSet;
public CustomString() {
this.myString = null;
this.isSet = false;
}
/**
* Returns a new string version of the current string where the alphabetical characters specified in the given arg, are removed.
*
* The alphabetical characters to be removed are case insensitive.
* 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) {
//I don't understand
}
}