Controller.java

package sample;

import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.TextArea;

public class Controller {

    @FXML
    private TextArea textArea;

    @FXML
    private void handleSubmit() {

        String tmp = textArea.getText();

        Thought t = new Thought(tmp);

        ThoughtManager tm = ThoughtManager.getInstance();

        tm.add(t);

    }
}