我试图让TableView在启动时以编程方式调整其列的大小以适应其内容，为了实现这一点，我发现了一种在绑定到侦听器时工作得很好的方法（例如{{1} }）。
但是当我尝试将其绑定到#onKeyPressed的{{1}}以便在没有任何用户操作的情况下调用它时，它会在showingProperty()上抛出primaryStage。
在previous post我暴露了一个类似的问题，不同之处在于我没有使用父布局（NullPointerException）来包裹columnToFitMethod.invoke(tableView.getSkin(), column, -1)。 @DVarga为我提供的solution工作直到我添加RootLayout。
以下是例外：
PersonTable如何设法以编程方式保留RootLaylout的大小？
这是我的代码：
RootLayoutPersonTable.fxml：
Exception in Application start method
java.lang.reflect.InvocationTargetException
...
Caused by: java.lang.RuntimeException: Exception in Application start method
...
Caused by: java.lang.NullPointerException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at columnstofit.MainApp$GUIUtil.fitColumns(MainApp.java:135)
at columnstofit.PersonTableController.setMainApp(PersonTableController.java:30)
at columnstofit.MainApp.showPersonTable(MainApp.java:98)
at columnstofit.MainApp.start(MainApp.java:60)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$162(LauncherImpl.java:863)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$175(PlatformImpl.java:326)
at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
... 1 more
Exception running application columnstofit.MainApp
PersonTableController：
package columnstofit;
import com.sun.javafx.scene.control.skin.TableViewSkin;
import java.awt.AWTException;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import javafx.application.Application;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.layout.AnchorPane;
import javafx.scene.layout.BorderPane;
import javafx.stage.Stage;
public class MainApp extends Application {
public static Stage primaryStage;
private static AnchorPane personTable;
private static BorderPane rootLayout;
PersonTableController controller;
private ObservableList<Person> personData = FXCollections.observableArrayList();
/**
* Constructor
*/
public MainApp() {
// i am entering this name just to force the resizing of the column
personData.add(new Person("Hansgggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg", "Muster"));
personData.add(new Person("Ruth", "Mueller"));
personData.add(new Person("Heinz", "Kurz"));
personData.add(new Person("Cornelia", "Meier"));
personData.add(new Person("Werner", "Meyer"));
personData.add(new Person("Lydia", "Kunz"));
personData.add(new Person("Anna", "Best"));
personData.add(new Person("Stefan", "Meier"));
}
/**
* Returns the data as an observable list of Persons.
* @return
*/
public ObservableList<Person> getPersonData() {
return personData;
}
@Override
public void start(Stage primaryStage) throws AWTException {
MainApp.primaryStage = primaryStage;
MainApp.primaryStage.setTitle("Names Table");
initRootLayout();
showPersonTable();
}
/**
* Initializes the root layout.
* @throws java.awt.AWTException
*/
public void initRootLayout() throws AWTException {
try
{
// Load root layout from fxml file.
FXMLLoader loader = new FXMLLoader();
loader.setLocation(MainApp.class.getResource("RootLayout.fxml"));
rootLayout = (BorderPane) loader.load();
// Show the scene containing the root layout.
Scene scene = new Scene(rootLayout);
MainApp.primaryStage.setScene(scene);
MainApp.primaryStage.show();
}
catch (IOException e) { e.printStackTrace(); }
}
public void showPersonTable() throws AWTException {
try
{
// Load person overview.
FXMLLoader loader = new FXMLLoader();
loader.setLocation(MainApp.class.getResource("PersonTable.fxml"));
personTable = (AnchorPane) loader.load();
// Set person overview into the center of root layout.
rootLayout.setCenter(personTable);
// Give the controller access to the main app.
controller = loader.getController();
controller.setMainApp(this);
}
catch (IOException e) { e.printStackTrace(); }
}
/**
* Returns the main stage.
* @return
*/
public Stage getPrimaryStage() {
return primaryStage;
}
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
launch(args);
}
public static class GUIUtil {
private static Method columnToFitMethod;
static
{
try
{
columnToFitMethod = TableViewSkin.class.getDeclaredMethod("resizeColumnToFitContent", TableColumn.class, int.class);
columnToFitMethod.setAccessible(true);
}
catch (NoSuchMethodException e) {e.printStackTrace();}
}
public static void fitColumns(TableView tableView) {
for (Object column : tableView.getColumns())
{
try { columnToFitMethod.invoke(tableView.getSkin(), column, -1); }
catch (IllegalAccessException | InvocationTargetException e) { e.printStackTrace(); }
}
}
}
public class Person {
private final StringProperty firstName;
private final StringProperty lastName;
public Person() {
this(null, null);
}
public Person(String firstName, String lastName) {
this.firstName = new SimpleStringProperty(firstName);
this.lastName = new SimpleStringProperty(lastName);
}
public String getFirstName() {
return firstName.get();
}
public void setFirstName(String firstName) {
this.firstName.set(firstName);
}
public StringProperty firstNameProperty() {
return firstName;
}
public String getLastName() {
return lastName.get();
}
public void setLastName(String lastName) {
this.lastName.set(lastName);
}
public StringProperty lastNameProperty() {
return lastName;
}
}
}
和RootLaylout.fxml：
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.TableColumn?>
<?import javafx.scene.control.TableView?>
<?import javafx.scene.layout.AnchorPane?>
<AnchorPane id="AnchorPane" stylesheets="@PersonTableStyle.css" xmlns="http://javafx.com/javafx/8.0.60" xmlns:fx="http://javafx.com/fxml/1" fx:controller="columnstofit.PersonTableController">
<TableView fx:id="tableView" layoutX="-39.0" layoutY="39.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
<columns>
<TableColumn fx:id="firstNameColumn" editable="false" minWidth="-1.0" prefWidth="-1.0" text="First Name" />
<TableColumn fx:id="lastNameColumn" editable="false" minWidth="-1.0" prefWidth="-1.0" text="Last Name" />
</columns>
<columnResizePolicy>
<TableView fx:constant="CONSTRAINED_RESIZE_POLICY" />
</columnResizePolicy>
</TableView>
</AnchorPane>