调用setText（）

Question

（我的英语不好。）

我是javafx的新秀，这是我第一次发布到论坛。

我有一个有关剧院预订的项目。我的程序中有3个剧院，我正在使用标签在每个剧院中显示电影数据，但是当我叫NullPointerException时得到setText()。

我检查了fx:controller和fx:id没关系。我还尝试从标签打印getText()，但得到同样的错误。 （我已经在标签上设置了文本“无电影”。）

这是我的代码

MainController：

package movie.view;

import java.io.IOException;

import javafx.fxml.FXML;
import javafx.scene.control.Label;
import movie.Main;

public class MainPageController {

    private Main main;
    @FXML public Label theaterData1;
    @FXML public Label theaterData2;
    @FXML public Label theaterData3;
    private String display;

    public MainPageController() {}
    @FXML
    private void goLogInPage() throws IOException{
        main.showLogInPageScene();
    }

    public void recieveData(String data)
    {
        display = data;     
    }

    @FXML
    public void setDataForTheater1()
    {
        theaterData1.setText(display);
    }

    @FXML
    public void setDataForTheater2()
    {
        theaterData2.setText(display);
    }

    @FXML
    public void setDataForTheater3()
    {
        theaterData3.setText(display);
    }
}

MainView FXML：

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.text.*?>
<?import javafx.geometry.*?>
<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.layout.BorderPane?>

<BorderPane prefHeight="768.0" prefWidth="1024.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="movie.view.MainPageController">
   <bottom>
      <HBox alignment="BOTTOM_RIGHT" prefHeight="100.0" prefWidth="200.0" BorderPane.alignment="CENTER">
         <children>
            <Button mnemonicParsing="false" onAction="#goLogInPage" text="For Admin Only">
               <HBox.margin>
                  <Insets bottom="15.0" right="15.0" />
               </HBox.margin>
            </Button>
         </children>
      </HBox>
   </bottom>
   <top>
      <Label text="Welcome to CSCU Theater" BorderPane.alignment="CENTER">
         <font>
            <Font size="30.0" />
         </font>
         <BorderPane.margin>
            <Insets top="20.0" />
         </BorderPane.margin>
      </Label>
   </top>
   <center>
      <GridPane BorderPane.alignment="CENTER">
        <columnConstraints>
          <ColumnConstraints hgrow="SOMETIMES" maxWidth="852.0" minWidth="10.0" prefWidth="817.0" />
            <ColumnConstraints hgrow="SOMETIMES" maxWidth="502.0" minWidth="10.0" prefWidth="207.0" />
        </columnConstraints>
        <rowConstraints>
          <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
          <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
          <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
        </rowConstraints>
         <children>
            <GridPane>
              <columnConstraints>
                <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
              </columnConstraints>
              <rowConstraints>
                <RowConstraints maxHeight="90.0" minHeight="10.0" prefHeight="51.0" vgrow="SOMETIMES" />
                <RowConstraints maxHeight="159.0" minHeight="10.0" prefHeight="150.0" vgrow="SOMETIMES" />
              </rowConstraints>
               <children>
                  <Label text="Theater 1">
                     <font>
                        <Font size="24.0" />
                     </font>
                     <GridPane.margin>
                        <Insets left="20.0" />
                     </GridPane.margin>
                  </Label>
                  <Label fx:id="theaterData1" text="No movie avaliable :(" GridPane.rowIndex="1">
                     <GridPane.margin>
                        <Insets left="20.0" />
                     </GridPane.margin>
                     <font>
                        <Font size="18.0" />
                     </font>
                  </Label>
               </children>
            </GridPane>
            <GridPane GridPane.rowIndex="1">
              <columnConstraints>
                <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
              </columnConstraints>
              <rowConstraints>
                <RowConstraints maxHeight="90.0" minHeight="10.0" prefHeight="55.0" vgrow="SOMETIMES" />
                <RowConstraints maxHeight="146.0" minHeight="10.0" prefHeight="146.0" vgrow="SOMETIMES" />
              </rowConstraints>
               <children>
                  <Label text="Theater 2">
                     <font>
                        <Font size="24.0" />
                     </font>
                     <GridPane.margin>
                        <Insets left="20.0" />
                     </GridPane.margin>
                  </Label>
                  <Label fx:id="theaterData2" text="No movie avaliable :(" GridPane.rowIndex="1">
                     <font>
                        <Font size="20.0" />
                     </font>
                     <GridPane.margin>
                        <Insets left="20.0" />
                     </GridPane.margin>
                  </Label>
               </children>
            </GridPane>
            <GridPane GridPane.rowIndex="2">
              <columnConstraints>
                <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
              </columnConstraints>
              <rowConstraints>
                <RowConstraints maxHeight="90.0" minHeight="10.0" prefHeight="54.0" vgrow="SOMETIMES" />
                <RowConstraints maxHeight="147.0" minHeight="10.0" prefHeight="147.0" vgrow="SOMETIMES" />
              </rowConstraints>
               <children>
                  <Label text="Theater 3">
                     <padding>
                        <Insets left="20.0" />
                     </padding>
                     <font>
                        <Font size="24.0" />
                     </font>
                  </Label>
                  <Label fx:id="theaterData3" text="No movie avaliable :(" GridPane.rowIndex="1">
                     <font>
                        <Font size="20.0" />
                     </font>
                     <GridPane.margin>
                        <Insets left="20.0" />
                     </GridPane.margin>
                  </Label>
               </children>
            </GridPane>
            <GridPane maxHeight="150.0" vgap="5.0" GridPane.columnIndex="1">
              <columnConstraints>
                <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
              </columnConstraints>
              <rowConstraints>
                <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
                <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
                <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
              </rowConstraints>
               <children>
                  <Label text="Select Round">
                     <font>
                        <Font size="18.0" />
                     </font>
                  </Label>
                  <ComboBox prefWidth="150.0" GridPane.rowIndex="1" />
                  <Button mnemonicParsing="false" text="Select Seat" GridPane.rowIndex="2" />
               </children>
            </GridPane>
            <GridPane maxHeight="150.0" GridPane.columnIndex="1" GridPane.rowIndex="1">
              <columnConstraints>
                <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
              </columnConstraints>
              <rowConstraints>
                <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
                <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
                <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
              </rowConstraints>
               <children>
                  <Label text="Select Round">
                     <font>
                        <Font size="18.0" />
                     </font>
                  </Label>
                  <ComboBox prefWidth="150.0" GridPane.rowIndex="1" />
                  <Button mnemonicParsing="false" text="Select Seat" GridPane.rowIndex="2" />
               </children>
            </GridPane>
            <GridPane maxHeight="150.0" GridPane.columnIndex="1" GridPane.rowIndex="2">
              <columnConstraints>
                <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
              </columnConstraints>
              <rowConstraints>
                <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
                <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
                <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
              </rowConstraints>
               <children>
                  <Label text="Select Round">
                     <font>
                        <Font size="18.0" />
                     </font>
                  </Label>
                  <ComboBox prefWidth="150.0" GridPane.rowIndex="1" />
                  <Button mnemonicParsing="false" text="Select Seat" GridPane.rowIndex="2" />
               </children>
            </GridPane>
         </children>
      </GridPane>
   </center>
</BorderPane>

我在这里得到NullPointerException theaterData1.setText(display);

任何帮助将不胜感激，请解释为什么会发生此错误。