由于 ArrayList,主构造函数中的 JavaFX 异常
JavaFX Exception in Main Constructor due to ArrayList
我是 JavaFx 编程的新手,现在在我的初始阶段,我正在用 javaFX 构建地址簿,但问题仍然存在,它在 Main Class 的构造函数中抛出异常。
当我使用 ObserverableList 时,我没有得到任何类型的 Exception,而当我尝试使用数组存储实体对象时,我得到了异常。
谁能给我解决这个问题的方法?
我想做的主要事情是 save ObserverableList 或 ArrayList object to a file.
package com.company;
import com.company.Controllers.DatabaseConnectJDBC;
import com.company.Controllers.MainWindowController;
import com.company.Controllers.secondWindowController;
import com.company.Model.EmployeeEntity;
import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.layout.AnchorPane;
import javafx.stage.Stage;
import java.io.*;
import java.util.ArrayList;
public class Main extends Application {
Stage primaryStage;
@Override
public void start(Stage primaryStage) throws Exception {
this.primaryStage=primaryStage;
mainWindow();
}
public void mainWindow() {
try{
FXMLLoader loader=new FXMLLoader(this.getClass().getResource("Views/MainWindow.fxml"));
AnchorPane pane=loader.load();
Scene scene=new Scene(pane);
MainWindowController controller=loader.getController();
controller.setMain(this);
primaryStage.setScene(scene);
primaryStage.setResizable(false);
primaryStage.show();
}catch (Exception e){
e.printStackTrace();
}
}
public void secondaryWindow() {
try{
FXMLLoader loader=new FXMLLoader(this.getClass().getResource("Views/secondaryWindow.fxml"));
AnchorPane pane=loader.load();
Scene scene=new Scene(pane);
Stage secondaryStage=new Stage();
secondWindowController controller=loader.getController();
controller.setMain(this,secondaryStage);
secondaryStage.setScene(scene);
secondaryStage.setResizable(false);
secondaryStage.show();
}catch (Exception e){
e.printStackTrace();
}
}
private ObservableList<EmployeeEntity> employeeObserveList= FXCollections.observableArrayList();
private ArrayList<EmployeeEntity> arrayList;
public ObservableList<EmployeeEntity> getEmployeeObserveList(){return employeeObserveList;}
public void setEmployeeObserveList(EmployeeEntity person){
getEmployeeObserveList().add(person);
}
public Main()
{
arrayList.add(new EmployeeEntity("3","126-B Millat Town","030123456","Abubaker","Usman"));
arrayList.add(new EmployeeEntity("4","127-B Millat Town","032123456","Asma","Rasool"));
arrayList.add(new EmployeeEntity("5","128-B Millat Town","035123456","Talha","Farooq"));
employeeObserveList = FXCollections.observableArrayList(arrayList);
employeeObserveList.addAll(arrayList);
}
异常
Exception in Application constructor
Exception in thread "main" java.lang.RuntimeException: Unable to construct Application instance: class com.company.Main
at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:907)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication6(LauncherImpl.java:182)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication12(LauncherImpl.java:819)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait6(PlatformImpl.java:326)
at com.sun.javafx.application.PlatformImpl.lambda$null4(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater5(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null9(WinApplication.java:191)
... 1 more
Caused by: java.lang.NullPointerException
at com.company.Main.<init>(Main.java:68)
... 13 more
更改此行
private ArrayList<EmployeeEntity> arrayList;
到
private List<EmployeeEntity> arrayList = new ArrayList<EmployeeEntity>();
您从未初始化 ArrayList。
我是 JavaFx 编程的新手,现在在我的初始阶段,我正在用 javaFX 构建地址簿,但问题仍然存在,它在 Main Class 的构造函数中抛出异常。 当我使用 ObserverableList 时,我没有得到任何类型的 Exception,而当我尝试使用数组存储实体对象时,我得到了异常。 谁能给我解决这个问题的方法? 我想做的主要事情是 save ObserverableList 或 ArrayList object to a file.
package com.company;
import com.company.Controllers.DatabaseConnectJDBC;
import com.company.Controllers.MainWindowController;
import com.company.Controllers.secondWindowController;
import com.company.Model.EmployeeEntity;
import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.layout.AnchorPane;
import javafx.stage.Stage;
import java.io.*;
import java.util.ArrayList;
public class Main extends Application {
Stage primaryStage;
@Override
public void start(Stage primaryStage) throws Exception {
this.primaryStage=primaryStage;
mainWindow();
}
public void mainWindow() {
try{
FXMLLoader loader=new FXMLLoader(this.getClass().getResource("Views/MainWindow.fxml"));
AnchorPane pane=loader.load();
Scene scene=new Scene(pane);
MainWindowController controller=loader.getController();
controller.setMain(this);
primaryStage.setScene(scene);
primaryStage.setResizable(false);
primaryStage.show();
}catch (Exception e){
e.printStackTrace();
}
}
public void secondaryWindow() {
try{
FXMLLoader loader=new FXMLLoader(this.getClass().getResource("Views/secondaryWindow.fxml"));
AnchorPane pane=loader.load();
Scene scene=new Scene(pane);
Stage secondaryStage=new Stage();
secondWindowController controller=loader.getController();
controller.setMain(this,secondaryStage);
secondaryStage.setScene(scene);
secondaryStage.setResizable(false);
secondaryStage.show();
}catch (Exception e){
e.printStackTrace();
}
}
private ObservableList<EmployeeEntity> employeeObserveList= FXCollections.observableArrayList();
private ArrayList<EmployeeEntity> arrayList;
public ObservableList<EmployeeEntity> getEmployeeObserveList(){return employeeObserveList;}
public void setEmployeeObserveList(EmployeeEntity person){
getEmployeeObserveList().add(person);
}
public Main()
{
arrayList.add(new EmployeeEntity("3","126-B Millat Town","030123456","Abubaker","Usman"));
arrayList.add(new EmployeeEntity("4","127-B Millat Town","032123456","Asma","Rasool"));
arrayList.add(new EmployeeEntity("5","128-B Millat Town","035123456","Talha","Farooq"));
employeeObserveList = FXCollections.observableArrayList(arrayList);
employeeObserveList.addAll(arrayList);
}
异常
Exception in Application constructor
Exception in thread "main" java.lang.RuntimeException: Unable to construct Application instance: class com.company.Main
at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:907)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication6(LauncherImpl.java:182)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication12(LauncherImpl.java:819)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait6(PlatformImpl.java:326)
at com.sun.javafx.application.PlatformImpl.lambda$null4(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater5(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null9(WinApplication.java:191)
... 1 more
Caused by: java.lang.NullPointerException
at com.company.Main.<init>(Main.java:68)
... 13 more
更改此行
private ArrayList<EmployeeEntity> arrayList;
到
private List<EmployeeEntity> arrayList = new ArrayList<EmployeeEntity>();
您从未初始化 ArrayList。