Eu continuo recebendo esse erro ao criar um método de pesquisa no meu código para pesquisar por string. Eu já passei por muitos exemplos tentando corrigir isso, mas não consigo encontrar nenhum. Obrigado por qualquer ajuda e aconselhamento que você pode dar.

public class runNote {

public static void main(String[] args) {
    // TODO Auto-generated method stub
    Notebook note = new Notebook();
    note.storeNote("happy");
    note.storeNote("hello there");
    note.storeNote("work at 5");
    note.storeNote("BBQ Time");
    note.storeNote("UNI!!!!");
    note.storeNote("Dont miss lecture at 9:15");
    System.out.println(note.numberOfNotes());
    note.showNote(1);
    note.searchNotes("hap");

}}




public class Notebook{


/**
 * Perform any initialization that is required for the
 * notebook.
 */
public Notebook()
{
    notes = new ArrayList();
}

/**
 * Store a new note into the notebook.
 * @param note The note to be stored.
 */
public void storeNote(String note)
{
    notes.add(note);
}

/**
 * @return The number of notes currently in the notebook.
 */
public int numberOfNotes()
{
    return notes.size();
}

/**
 * A simple search engine to find the correct notes.
 */
public void searchNotes(String search){ 
    for (String item : notes){
        if (item.contains(search)){
        System.out.println(item);
        }
    }
}

/**
 * Show a note.
 * @param noteNumber The number of the note to be shown.
 */
public void showNote(int noteNumber)
{
    if(noteNumber < 0) {
        // This is not a valid note number, so do nothing.
    }
    else if(noteNumber < numberOfNotes()) {
        // This is a valid note number, so we can print it.
        System.out.println(notes.get(noteNumber));
    }
    else {
        // This is not a valid note number, so do nothing.
    }
}
}