how do I code to replace instanceof (see in bold) in this code? please shiw full code!!

WordNode.java

/**

* This is a class for Sentence.

*/

public class WordNode implements Sentence {

private String word;

private Sentence rest;

/**

* This is a constructor for the Sentence Class.

*

* @param word - string.

* @param rest - a Sentence.

*/

public WordNode(String word, Sentence rest) {

this.word = word;

this.rest = rest;

}

/**

* Does: Calculates the total number of words in a Sentence.

*

* @return - The total number of words from "current" + the rest of the words.

*/

@Override

public int getNumberOfWords() {

return 1 + this.rest.getNumberOfWords();

}

/**

* Does: Determines the longest word in the sentence.

*

* @return - A string of the longest word.

*/

@Override

public String longestWord() {

if (word.length() >= this.rest.longestWord().length()) {

return this.word;

}

return this.rest.longestWord();

}

/**

* Does: Adds a period to the end of the string if there none.

*

* @return - a String.

*/

@Override

public String toString() {

if (this.rest.toString().equals("")) {

// If we are at the end of the word nodes

// and check for last node is Empty Node

return this.word + ".";

}

if (rest instanceof PunctuationNode) {

return this.word + this.rest.toString();

}

return this.word + " " + this.rest.toString();

}

/**

* Does: clones a sentence.

*

* @return - a String.

*/

@Override

public Sentence clone() {

return new WordNode(this.word, this.rest.clone());

}

/**

* Does: merges a sentence.

*

* @return - a String.

*/

@Override

public Sentence merge(Sentence secondSentence) {

return new WordNode(this.word, this.rest.merge(secondSentence));

}

}