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所以有人请让我知道我在这里做错了什么。我的目标是将摩托车添加到 mInventory(我已创建并从单独的包导入)。但是，我的代码中仍然出现错误。我参加了 Treehouse 的 Java 类(class)，现在我正尝试使用 IntelliJ，但我不禁觉得他们真的只是把我们扔到那里，而没有真正解释 IntelliJ 的工作原理。有人给我一些建议吗？？？
这是 Main.java:
package sample;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
public class Main extends Application {
@Override
public void start(Stage primaryStage) throws Exception{
Parent root = FXMLLoader.load(getClass().getResource("/fxml/sample.fxml"));
primaryStage.setTitle("Store Motorcycle");
primaryStage.setScene(new Scene(root, 500, 400));
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
这是我的 Controller 类:
package sample;
import javafx.event.ActionEvent;
import sample.com.gardnerwebideas.Inventory;
import sample.com.gardnerwebideas.Motorcycle;
import javafx.fxml.FXML;
import javafx.scene.control.TextField;
import java.util.ArrayList;
public class Controller {
@FXML private TextField bikeYear;
@FXML private TextField bikeMake;
@FXML private TextField bikeModel;
@FXML private TextField bikeColor;
@FXML private TextField bikePrice;
private Inventory mInventory = new Inventory();
public void userCreateBike(ActionEvent actionEvent) {
Motorcycle motorcycle = newMotorcycle();
System.out.printf("Adding: %s", motorcycle);
mInventory.addMotorcycle(motorcycle);
}
public Motorcycle newMotorcycle() {
String year = bikeYear.getText();
String make = bikeMake.getText();
String model = bikeModel.getText();
String color = bikeColor.getText();
String price = bikePrice.getText();
return new Motorcycle(year, make, model, color, price);
}
}
这是我的库存类:
package sample.com.gardnerwebideas;
import java.util.ArrayList;
import java.util.List;
public class Inventory {
private List<Motorcycle> mInventory;
public Inventory() {
mInventory = new ArrayList<>();
}
public void addMotorcycle(Motorcycle motorcycle) {
mInventory.add(motorcycle);
}
public int getInventoryCount() {
return mInventory.size();
}
@Override
public String toString() {
return "Inventory{" +
"mInventory=" + mInventory +
'}';
}
}
最后是摩托车类:
package sample.com.gardnerwebideas;
public class Motorcycle {
private String mYear;
private String mMake;
private String mModel;
private String mColor;
private String mPrice;
public Motorcycle(String year, String make, String model, String color, String price) {
mYear = year;
mMake = make;
mModel = model;
mColor = color;
mPrice = price;
}
public String getYear() {
return mYear;
}
public String getMake() {
return mMake;
}
public String getModel() {
return mModel;
}
public String getColor() {
return mColor;
}
public String getPrice() {
return mPrice;
}
@Override
public String toString() {
return "Motorcycle:" +
"Year: " + mYear + "\n" +
"Make: " + mMake + "\n" +
"Model: " + mModel + "\n" +
"Color: " + mColor + "\n" +
"Price: " + mPrice + "\n";
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Motorcycle that = (Motorcycle) o;
if (mYear != null ? !mYear.equals(that.mYear) : that.mYear != null) return false;
if (mMake != null ? !mMake.equals(that.mMake) : that.mMake != null) return false;
if (mModel != null ? !mModel.equals(that.mModel) : that.mModel != null) return false;
if (mColor != null ? !mColor.equals(that.mColor) : that.mColor != null) return false;
return !(mPrice != null ? !mPrice.equals(that.mPrice) : that.mPrice != null);
}
@Override
public int hashCode() {
int result = mYear != null ? mYear.hashCode() : 0;
result = 31 * result + (mMake != null ? mMake.hashCode() : 0);
result = 31 * result + (mModel != null ? mModel.hashCode() : 0);
result = 31 * result + (mColor != null ? mColor.hashCode() : 0);
result = 31 * result + (mPrice != null ? mPrice.hashCode() : 0);
return result;
}
}
FXML:
<?xml version="1.0" encoding="UTF-8"?>
<?import java.lang.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.text.*?>
<?import javafx.geometry.Insets?>
<?import javafx.scene.layout.GridPane?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.text.Text?>
<?import javafx.scene.control.TextField?>
<GridPane alignment="CENTER"
stylesheets="/css/style.css"
xmlns="http://javafx.com/javafx/8"
xmlns:fx="http://javafx.com/fxml/1"
fx:controller="sample.Controller">
<children>
<Text styleClass="title"
text="Add a motorcycle:"
GridPane.columnSpan="2"
GridPane.halignment="CENTER"
GridPane.rowIndex="0" />
<Text styleClass="textTitle"
text="Year:"
GridPane.columnIndex="0"
GridPane.rowIndex="1" />
<TextField fx:id="bikeYear"
GridPane.columnIndex="1"
GridPane.rowIndex="1" />
<Text styleClass="textTitle"
text="Make:"
GridPane.columnIndex="0"
GridPane.rowIndex="2" />
<TextField fx:id="bikeMake"
alignment="TOP_LEFT"
GridPane.columnIndex="1"
GridPane.rowIndex="2" />
<Text styleClass="textTitle"
text="Model:"
GridPane.columnIndex="0"
GridPane.rowIndex="3" />
<TextField fx:id="bikeModel"
GridPane.columnIndex="1"
GridPane.rowIndex="3" />
<Text styleClass="textTitle"
text="Color:"
GridPane.columnIndex="0"
GridPane.rowIndex="4" />
<TextField fx:id="bikeColor"
GridPane.columnIndex="1"
GridPane.rowIndex="4" />
<Text styleClass="textTitle"
text="Price:"
GridPane.columnIndex="0"
GridPane.rowIndex="5" />
<TextField fx:id="bikePrice"
GridPane.columnIndex="1"
GridPane.rowIndex="5" />
<Button onAction="#userCreateBike"
styleClass="button"
text="Submit"
GridPane.columnSpan="2"
GridPane.halignment="CENTER"
GridPane.rowIndex="6" />
</children>
</GridPane>
如果有任何不清楚的地方，让我重复一遍...导致我出现问题的是以下行:mInventory.addMotorcycle(摩托车);除此之外，我的代码可以工作。它从我的 TextFields 获取信息，甚至将其打印到控制台......但它不会将新的摩托车添加到 mInventory。
哦...这是我收到的错误消息...
java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1774)
at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1657)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Node.fireEvent(Node.java:8411)
at javafx.scene.control.Button.fire(Button.java:185)
at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:182)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:96)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3757)
at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:352)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:275)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$355(GlassViewEventHandler.java:388)
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:387)
at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
at com.sun.glass.ui.View.notifyMouse(View.java:937)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1769)
... 45 more
Caused by: java.lang.NullPointerException
at sample.Controller.userCreateBike(Controller.java:26)
... 55 more
最佳答案
您的 Controller 没有构造函数，也没有 initialize() 方法。
首先在现在所在的位置定义成员private Inventory mInventory;，然后在构造函数或initialize()方法中创建新对象(mInventory = new Inventory();)。
关于java - 无法使用包中的方法将对象存储在 List<Object> 中？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/33159848/
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0
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