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我想從我的java控制器類中的另一個類調用一個方法，但那似乎不起作用，因爲當我嘗試單擊loginbutton時出現錯誤。 這是我正在嘗試做的 加載FXML >>輸入登錄名和密碼>>點擊登錄btn >>調用另一個類的frm方法來檢查憑證 當我單擊登錄按鈕時遇到錯誤作爲運行系統從JavaFX控制器調用另一個類的方法？
第二類（FRM其中i調用方法）
package javafxapplication4;
import static globalmethods.GlobalMethods.Display_Text;
public class CheckLogin{
public static final String USERNAME = "admin";//Store the credentials in a file
public static final String PASSWORD = "admin";//then retrive them here
String username, password;
static void startCheck() {
CheckLogin obj = new CheckLogin();
obj.getVars();
obj.checkLoginCredentials();
}
public void getVars() {
LoginController obj1 = new LoginController();
username = obj1.getUsername_i();
password = obj1.getPassword_i();
}
public void checkLoginCredentials() {
if (username.equals(USERNAME) && password.equals(PASSWORD)) {
Display_Text("Login Successful!");
} else {
Display_Text("Failed to Login. Incorrect Username and/or Password");
}
}
}
JavaFX的FXML
<?xml version="1.0" encoding="UTF-8"?>
<?import com.jfoenix.controls.JFXButton?>
<?import com.jfoenix.controls.JFXTextField?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.effect.ColorAdjust?>
<?import javafx.scene.effect.DropShadow?>
<?import javafx.scene.image.Image?>
<?import javafx.scene.image.ImageView?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.text.Font?>
<?import javafx.scene.text.Text?>
<AnchorPane id="AnchorPane" prefHeight="253.0" prefWidth="417.0" style="- fx-background-color: #03A9F4;" xmlns="http://javafx.com/javafx/8.0.111" xmlns:fx="http://javafx.com/fxml/1" fx:controller="javafxapplication4.LoginController">
<children>
<Text fill="WHITE" layoutX="139.0" layoutY="30.0" strokeType="OUTSIDE" strokeWidth="0.0" text="Welcome" textAlignment="CENTER" wrappingWidth="131.6708984375">
<font>
<Font size="28.0" />
</font>
</Text>
<JFXTextField fx:id="username_text" accessibleText="username_text" alignment="CENTER" focusColor="WHITE" labelFloat="true" layoutX="120.0" layoutY="78.0" promptText="Username" unFocusColor="#bdbdbd">
<effect>
<ColorAdjust />
</effect></JFXTextField>
<JFXTextField fx:id="password_text" accessibleText="password_text" alignment="CENTER" focusColor="WHITE" labelFloat="true" layoutX="121.0" layoutY="127.0" prefHeight="21.0" prefWidth="169.0" promptText="Password" unFocusColor="#bdbdbd" />
<JFXButton fx:id="login_btn" buttonType="RAISED" layoutX="165.0" layoutY="199.0" onAction="#OnLoginClicked" prefHeight="40.0" prefWidth="87.0" style="-fx-background-color: #FFC107;" text="Login" />
<Label fx:id="loginresp_lab" alignment="CENTER" layoutX="76.0" layoutY="159.0" prefHeight="21.0" prefWidth="258.0" textAlignment="CENTER" textFill="#d32f2f">
<font>
<Font name="System Bold" size="15.0" />
</font>
</Label>
<ImageView fx:id="close_btn" fitHeight="29.0" fitWidth="30.0" focusTraversable="true" layoutX="388.0" layoutY="4.0" onMouseClicked="#OnExitClicked" pickOnBounds="true" preserveRatio="true" smooth="false">
<image>
<Image url="@xclose.png" />
</image>
<effect>
<DropShadow blurType="GAUSSIAN" color="#000000af" />
</effect>
</ImageView>
</children>
</AnchorPane>
JAVA CLASS
}
JAVA CONTROLLER 包javafxapplication4;
import com.jfoenix.controls.JFXButton;
import com.jfoenix.controls.JFXTextField;
import static globalmethods.GlobalMethods.Display_Text;
import java.io.IOException;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.event.Event;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.fxml.JavaFXBuilderFactory;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.image.ImageView;
import javafx.scene.input.MouseEvent;
import javafx.stage.Stage;
import static javafxapplication4.CheckLogin.startCheck;
public class LoginController implements Initializable {
CheckLogin obj = new CheckLogin();
private String Username_i, Password_i;
@FXML
private JFXTextField username_text;
@FXML
private JFXTextField password_text;
@FXML
private JFXButton login_btn;
@FXML
private Label loginresp_lab;
@FXML
void OnLoginClicked(ActionEvent event) {
startCheck();
}
public String getUsername_i() {
return Username_i;
}
public String getPassword_i() {
return Password_i;
}
@FXML
private ImageView close_btn;
@FXML
void OnExitClicked(MouseEvent event) {
Display_Text("Exit!");
System.exit(0);
}
@Override
public void initialize(URL url, ResourceBundle rb) {
// TODO
}
}
ERROR
Exception in thread "JavaFX Application Thread" 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:8413)
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$MouseEventNotification.run(GlassViewEventHandler.java:381)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$354(GlassViewEventHandler.java:417)
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:416)
at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
at com.sun.glass.ui.View.notifyMouse(View.java:937)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1769)
... 48 more
Caused by: java.lang.NullPointerException
at javafxapplication4.CheckLogin.checkLoginCredentials(CheckLogin.java:25)
at javafxapplication4.CheckLogin.startCheck(CheckLogin.java:14)
at javafxapplication4.LoginController.OnLoginClicked(LoginController.java:52)
... 58 more
您好！歡迎來到Stack Overflow。請回顧[如何提出一個好問題]（http://stackoverflow.com/help/how-to-ask）。就目前而言，你已經拋棄了一堆代碼，並說你有一個錯誤，但沒有堆棧跟蹤或上下文。 –
比以前好？ –