Javafx java.lang.reflect.InvocationTargetException当我尝试更改标签时'；s文本值_Javafx_Fxml

Javafx java.lang.reflect.InvocationTargetException当我尝试更改标签时'；s文本值

javafx

Javafx java.lang.reflect.InvocationTargetException当我尝试更改标签时'；s文本值,javafx,fxml,Javafx,Fxml,下面是一个使用fxml和netbeans的javafx的简单标签项目。问题是，当我使用 StartFomulars.setText("abc"); 它只是得到下面给出的一个异常这是main的代码 package main; import javafx.application.Application; import javafx.fxml.FXMLLoader; import javafx.scene.Parent; import javafx.scene.Scene; import ja

下面是一个使用fxml和netbeans的javafx的简单标签项目。问题是，当我使用

StartFomulars.setText("abc");

它只是得到下面给出的一个异常

这是main的代码

package main;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;


public class Start extends Application {

    @Override
    public void start(Stage stage) throws Exception {
        Prove Controller = new Prove();
        Controller.launchController(stage);
    }

    public static void main(String[] args) {
        launch(args);
    }

}

fxml

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

<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.paint.*?>

<AnchorPane id="AnchorPane" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="720.0" prefWidth="1080.0" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/2.2">
  <children>
    <GridPane layoutX="0.0" layoutY="0.0" prefHeight="720.0" prefWidth="1080.0">
      <children>
        <GridPane GridPane.columnIndex="0" GridPane.rowIndex="0">
          <columnConstraints>
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
            <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>
        </GridPane>
        <GridPane GridPane.columnIndex="1" GridPane.rowIndex="1">
          <children>
            <GridPane GridPane.columnIndex="0" GridPane.rowIndex="0">
              <columnConstraints>
                <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
                <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 minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
                <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
              </rowConstraints>
            </GridPane>
          </children>
          <columnConstraints>
            <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
          </columnConstraints>
          <rowConstraints>
            <RowConstraints maxHeight="282.0" minHeight="10.0" prefHeight="282.0" vgrow="SOMETIMES" />
            <RowConstraints maxHeight="281.0" minHeight="10.0" prefHeight="281.0" vgrow="SOMETIMES" />
          </rowConstraints>
        </GridPane>
        <GridPane GridPane.columnIndex="0" GridPane.rowIndex="1">
          <children>
            <Label text="Given: " GridPane.columnIndex="0" GridPane.rowIndex="0" />
            <Label text="Prove: " GridPane.columnIndex="0" GridPane.rowIndex="1" />
            <Label text="Goal: " GridPane.columnIndex="0" GridPane.rowIndex="2" />
            <Label fx:id="StartFomulars" text="StartFomulars" GridPane.columnIndex="1" GridPane.rowIndex="0" />
            <Label fx:id="GoalFomular" text="GoalFomular" GridPane.columnIndex="1" GridPane.rowIndex="2" />
          </children>
          <columnConstraints>
            <ColumnConstraints hgrow="SOMETIMES" maxWidth="457.0" minWidth="10.0" prefWidth="125.0" />
            <ColumnConstraints hgrow="SOMETIMES" maxWidth="802.0" minWidth="10.0" prefWidth="790.0" />
          </columnConstraints>
          <rowConstraints>
            <RowConstraints maxHeight="188.0" minHeight="10.0" prefHeight="156.0" vgrow="SOMETIMES" />
            <RowConstraints maxHeight="364.0" minHeight="10.0" prefHeight="364.0" vgrow="SOMETIMES" />
            <RowConstraints maxHeight="186.0" minHeight="10.0" prefHeight="43.0" vgrow="SOMETIMES" />
          </rowConstraints>
        </GridPane>
      </children>
      <columnConstraints>
        <ColumnConstraints hgrow="SOMETIMES" maxWidth="915.0" minWidth="10.0" prefWidth="915.0" />
        <ColumnConstraints hgrow="SOMETIMES" maxWidth="539.0" minWidth="10.0" prefWidth="165.0" />
      </columnConstraints>
      <rowConstraints>
        <RowConstraints maxHeight="359.0" minHeight="10.0" prefHeight="157.0" vgrow="SOMETIMES" />
        <RowConstraints maxHeight="582.0" minHeight="10.0" prefHeight="563.0" vgrow="SOMETIMES" />
      </rowConstraints>
    </GridPane>
  </children>
</AnchorPane>

你的结构很不寻常。如图所示，构造应用程序类、FXML文件和控制器更为正常

设置好之后，控制器类和FXML之间没有连接。因此，注释为

@FXML

的字段永远不会初始化

其工作方式是，

fxmloader

的

load（…）

方法将解析FXML文件。如果加载器上设置了控制器，则定义了

fx:id

属性的任何元素都将被注入控制器中匹配的

@FXML

注释字段中

在

FXMLLoader

上设置控制器基本上有两种方法。第一个是在FXML文件的根元素上定义一个

fx:controller

属性。这将导致FXML加载程序创建指定类的新实例，并将其用作其控制器。注意，这在您的情况下不起作用，因为您希望控制器是您已经创建的

Prove

实例，而不是

Prove

类的新实例

第二种方法是创建

fxmloader

实例（而不是依赖当前使用的

static

fxmloader.load（URL）

方法），并在该实例上调用

setController（…）

。所以（我认为）取消注释

//fxmlLoader.setController(this);

这条线会让它工作的

您可能还需要分隔字段的声明，即：

@FXML
private Label StartFomulars ;
@FXML
private Label GoalFomular;

（如果没有这种改变，它可能会起作用，我从来没有像你那样尝试过。）

您可能还应该在

Prove

的构造函数中取出

try{…}catch（…）{…}

结构（因为您声明它

抛出IOException

），或者至少在

catch

块中执行一些操作。现在，如果加载FXML时发生异常，您将不知道它，您只需继续尝试并设置标签的文本。

您的结构非常不寻常。如图所示，构造应用程序类、FXML文件和控制器更为正常