fixed bug

src/sample/sample.fxml

@@ -6,14 +6,14 @@
 <?import javafx.scene.layout.AnchorPane?>
 <?import javafx.scene.text.Text?>
 
-<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="498.0" prefWidth="700.0" xmlns="http://javafx.com/javafx/11.0.1" fx:controller="sample.Controller" xmlns:fx="http://javafx.com/fxml/1">
+<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="498.0" prefWidth="700.0" xmlns="http://javafx.com/javafx/11.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="sample.Controller">
    <children>
-      <Button id="submitButton" layoutX="100.0" layoutY="423.0" mnemonicParsing="false" prefHeight="35.0" prefWidth="129.0" text="Submit thought" />
-      <TextArea id="textBox" layoutX="59.0" layoutY="299.0" prefHeight="106.0" prefWidth="307.0" promptText="Write your thought here..." />
+      <Button id="submitButton" layoutX="100.0" layoutY="423.0" mnemonicParsing="false" onAction="#handleSubmit" prefHeight="35.0" prefWidth="129.0" text="Submit thought" />
+      <TextArea id="textBox" fx:id="textArea" layoutX="59.0" layoutY="299.0" prefHeight="106.0" prefWidth="307.0" promptText="Write your thought here..." />
       <Text id="thoughtField" layoutX="65.0" layoutY="31.0" strokeType="OUTSIDE" strokeWidth="0.0" text="Your thoughts" />
       <ScrollPane id="scrollyboi" layoutX="1.0" layoutY="40.0" prefHeight="258.0" prefWidth="700.0">
          <content>
-            <Text id="thoughtId" strokeType="OUTSIDE" strokeWidth="20.0"  wrappingWidth="33.22460746765137" text="Text" />
+            <Text id="thoughtId" strokeType="OUTSIDE" strokeWidth="20.0" text="Text" wrappingWidth="33.22460746765137" />
          </content>
       </ScrollPane>
    </children>