TextClass.java

public class TextClass {
    private String text;


    /*
        Getter and Setter
     */
    public String getText() {
        return text;
    }

    public void setText(String text) {
        this.text = text;
    }

    /*
        Constructors
     */

    public TextClass(String text) {
        this.text = text;
    }

    public TextClass() {
        this.text = "default";
    }

    /*
        Methods
     */

    public int numberOfWords(String text) {
        String trim = text.trim();
        if (trim.isEmpty())
            return 0;
        return trim.split("\\s+").length; // \s regex metacharacter which finds whitespace character and split returns array of splitted words
    }

    public int numberOfCharacters(String text) {
        String trim = text.trim();
        return trim.toCharArray().length;
    }

    public int numberOfSentences(String text) {
        String trim = text.trim();
        if(trim.equals("")){
            return 0;
        }

        int i;
        int counter = 0; //for counting sentences. Only the dot (.) seperates the sentences in this case

        for (i = 0; i < trim.length(); i++) {
            if (trim.charAt(i) == '.')
                counter++;
        }
        if(counter == 0){
            return counter += 1;
        }
        return counter;
    }

    public boolean doesWordExist(String word, String text) {
        if (text.indexOf(word) != -1) {
            return true;
        } else {
            return false;
        }
    }

}