24. Write a program on Java that determines if an input sentence is a palindrome, for example, A man, a plan, a canal, Panama! You ignore the punctuation marks, blanks, and case of the letters. Repeat the operation until an empty string is entered. The output should be like this:

Enter Sentence: A man, a plan, a canal, Panama! Palindrome ! ! ! Enter Sentence: john, tree, river Not a Palindrome Enter Sentence: Received empty string, exiting now...