Question

尝试更改ActionEvent上的标签时，我收到nullpointerException。

这是困扰我的代码，我在player1Label.setText（player1.name）上获得了nullpointer异常;线

我尝试通过编写player1Label.setText（“Eric”）手动完成;但仍然得到同样的例外。

Player player1 = new Player();
Player player2 = new Player();


public Label player1Label;
@FXML
public Label player2Label;
@FXML
private TextField player2Field;
@FXML
private TextField player1Field;
@FXML
private Button startButton;

    @FXML
private void startGame(ActionEvent event) throws IOException {

    if (event.getSource() == startButton) {

        player1.name = player1Field.getCharacters().toString();
        player2.name = player2Field.getCharacters().toString();


            player1Label.setText(player1.name);
            player2Label.setText(player2.name);


        Parent Monpoly = FXMLLoader.load(getClass().getResource("FXMLMonopoly.fxml"));
        Scene scene = new Scene(Monpoly);
        Stage stage = (Stage) startButton.getScene().getWindow();
        stage.setScene(scene);
        stage.show();

    }

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

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

<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="528.0" prefWidth="797.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="jope015gop_4.pkg1.FXMLDocumentController">
   <children>
      <ScrollPane fx:id="player1Pane" hbarPolicy="NEVER" layoutX="77.0" layoutY="247.0" prefHeight="200.0" prefWidth="200.0" />
      <ScrollPane fx:id="player2Pane" hbarPolicy="NEVER" layoutX="527.0" layoutY="247.0" prefHeight="200.0" prefWidth="200.0" />
      <Label fx:id="player1Label" layoutX="77.0" layoutY="233.0" text="Player 1" />
      <Label fx:id="player2Label" layoutX="527.0" layoutY="233.0" text="Player 2" />
      <Button id="rollDiceButton" fx:id="rollDiceButton" layoutX="357.0" layoutY="149.0" mnemonicParsing="false" onAction="#nextTurnClicked" prefHeight="43.0" prefWidth="81.0" text="Roll dice" />
      <Label layoutX="319.0" layoutY="55.0" text="MATADOR">
         <font>
            <Font name="System Bold" size="30.0" />
         </font>
      </Label>
   </children>
</AnchorPane>


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

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

<AnchorPane id="AnchorPane" prefHeight="398.0" prefWidth="671.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="jope015gop_4.pkg1.FXMLDocumentController">
   <children>
      <TextField fx:id="player1Field" layoutX="298.0" layoutY="108.0" />
      <TextField fx:id="player2Field" layoutX="298.0" layoutY="162.0" />
      <Label layoutX="225.0" layoutY="112.0" text="Spiller 1" />
      <Label layoutX="225.0" layoutY="166.0" text="Spiller 2" />
      <Button fx:id="startButton" layoutX="279.0" layoutY="281.0" mnemonicParsing="false" onAction="#startGame" prefHeight="25.0" prefWidth="115.0" text="Start" />
   </children>
</AnchorPane>

我也读过这个：label.setText NullPointerException但它无法帮助我。

Answer 1

您没有标记您的标签。你需要像这样编码。

player1Label = new Label();

希望这会有所帮助。

在场景之间切换时，Label.setText为nullPointerException

1 个答案: