- html - 出于某种原因,IE8 对我的 Sass 文件中继承的 html5 CSS 不友好?
- JMeter 在响应断言中使用 span 标签的问题
- html - 在 :hover and :active? 上具有不同效果的 CSS 动画
- html - 相对于居中的 html 内容固定的 CSS 重复背景?
我正在研究 JavaFX 和 SQL 项目。首先,登录窗口打开,如果用户名和密码与我的数据库中存储的用户名和密码匹配,则会弹出 AddCustomer 详细信息窗口[在此之前工作正常]。我的数据库中将有一个表用于用户条目。但是当我点击“保存”按钮时,我收到这样的错误
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: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$MouseEventNotification.run(GlassViewEventHandler.java:394)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$353(GlassViewEventHandler.java:432)
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:431)
at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
at com.sun.glass.ui.View.notifyMouse(View.java:937)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$147(WinApplication.java:177)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1769)
... 48 more
Caused by: java.lang.NullPointerException
at sample.MysqlConnector.<init>(MysqlConnector.java:22)
at sample.AddCustomer.addcustomer(AddCustomer.java:52)
... 58 more
我的Main.java
package sample;
import javafx.application.Application;
import javafx.fxml.*;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
public class Main extends Application {
@Override
public void start(Stage primaryStage) {
try {
Parent root = FXMLLoader.load(getClass().getResource("login1.fxml"));
primaryStage.setTitle("NOVOTEL HOTEL ");
primaryStage.setScene(new Scene(root, 500, 475));
primaryStage.show();
}
catch(Exception e )
{
e.printStackTrace();
}
}
public static void main(String[] args) {
launch(args);
}
}
我的MysqlConnector.java
package sample;
import com.sun.istack.internal.NotNull;
import com.sun.istack.internal.Nullable;
import javafx.fxml.FXML;
import java.sql.*;
public class MysqlConnector {
@FXML
public static Statement stmt;
@FXML
public static Connection conn;
public MysqlConnector() {
Connector();
String TableName = "CustomerDetails";
try {
stmt = conn.createStatement();
DatabaseMetaData dbm = conn.getMetaData();
ResultSet tables = dbm.getTables(null, null, TableName.toUpperCase(), null);
if (tables.next()) {
System.out.println("Ready to go");
} else {
stmt.execute("CREARE TABLE " + TableName + "("
+ " customername varchar(45) primary key,"
+ " customername int" +
"+ customernumber int" +
"+ customerstay int" +
"+ customerguests varchar(45)"
+ ")");
}
} catch (SQLException e1) {
System.err.println(e1.getMessage());
}
}
@Nullable
@NotNull
public static Connection Connector() {
try {
Class.forName("com.mysql.jdbc.Driver");
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/login", "root", "password");
return conn;
} catch (Exception e) {
return null;
}
}
@NotNull
@Nullable
public static ResultSet executeQuery(String query) {
ResultSet result ;
try {
stmt = conn.createStatement();
result=stmt.executeQuery(query);
} catch (SQLException e) {
System.out.println("Error here");
e.printStackTrace();
return null;
}
return result;
}
@NotNull
@Nullable
public boolean executeAction(String qu) {
try {
stmt = conn.createStatement();
stmt.execute(qu);
return true;
} catch (SQLException e) {
e.printStackTrace();
return false;
}
}
}
我的LoginModel.java
package sample;
import com.sun.istack.internal.NotNull;
import com.sun.istack.internal.Nullable;
import javafx.fxml.FXML;
import java.sql.*;
public class MysqlConnector {
@FXML
public static Statement stmt;
@FXML
public static Connection conn;
public MysqlConnector() {
String TableName = "CustomerDetails";
try {
stmt = conn.createStatement();
DatabaseMetaData dbm = conn.getMetaData();
ResultSet tables = dbm.getTables(null, null, TableName.toUpperCase(), null);
if (tables.next()) {
System.out.println("Ready to go");
} else {
stmt.execute("CREARE TABLE " + TableName + "("
+ " customername varchar(45) primary key,"
+ " customername int" +
"+ customernumber int" +
"+ customerstay int" +
"+ customerguests varchar(45)"
+ ")");
}
} catch (SQLException e1) {
System.err.println(e1.getMessage());
}
}
@Nullable
@NotNull
public static Connection Connector() {
try {
Class.forName("com.mysql.jdbc.Driver");
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/login", "root", "password");
return conn;
} catch (Exception e) {
return null;
}
}
@NotNull
@Nullable
public static ResultSet executeQuery(String query) {
ResultSet result ;
try {
stmt = conn.createStatement();
result=stmt.executeQuery(query);
} catch (SQLException e) {
System.out.println("Error here");
e.printStackTrace();
return null;
}
return result;
}
@NotNull
@Nullable
public boolean executeAction(String qu) {
try {
stmt = conn.createStatement();
stmt.execute(qu);
return true;
} catch (SQLException e) {
e.printStackTrace();
return false;
}
}
}
我的 Controller 类
import com.sun.istack.internal.Nullable;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.stage.*;
import javafx.scene.*;
import javafx.scene.layout.*;
import javafx.scene.control.*;
import javafx.geometry.*;
import javafx.fxml.Initializable;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import java.net.URL;
import java.sql.SQLException;
import java.util.ResourceBundle;
import javafx.*;
public class Controller implements Initializable {
@NotNull
@Nullable
public LoginModel loginModel = new LoginModel();
@FXML
private Label isConnected,db;
@FXML
private TextField txtUsername;
@FXML
private TextField txtpassword;
@FXML
Button abutton = new Button("Login");
private AddCustomer addCustomer;
@Override
public void initialize(URL location, ResourceBundle resources) {
// TODO Auto-generated method stub
if (loginModel.isDBConnected()) {
db.setText("Connected to DATABASE");
} else {
db.setText("Not Connected");
}
}
public void Login (ActionEvent event ) {
try {
if (loginModel.isLogin(txtUsername.getText(), txtpassword.getText())) {
isConnected.setText("Correct");
try {
FXMLLoader addCustomer= new FXMLLoader(getClass().getResource("/sample/addcustomer.fxml"));
Parent root1 = (Parent)addCustomer.load();
Stage stage = new Stage();
stage.setScene(new Scene(root1));
stage.setTitle("ENTRY RECORD");
stage.show();
}
catch (Exception e){
e.printStackTrace();
}
} else {
Alert alert=new Alert(Alert.AlertType.ERROR);
alert.setHeaderText(null);
alert.setContentText("YOU ARE NOT AUTHENTICATED");
alert.show();
}
} catch (SQLException e) {
isConnected.setText("Incorrect");
e.printStackTrace();
}
}
}
COntroller类的FXML
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.PasswordField?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.text.Font?>
<AnchorPane prefHeight="335.0" prefWidth="526.0" xmlns="http://javafx.com/javafx/8.0.121" xmlns:fx="http://javafx.com/fxml/1" fx:controller="sample.Controller">
<children>
<Label id="isConnected" fx:id="isConnected" layoutX="69.0" layoutY="27.0" prefHeight="45.0" prefWidth="165.0" textAlignment="CENTER" textFill="#e81313">
<font>
<Font size="15.0" />
</font></Label>
<TextField fx:id="txtUsername" accessibleRole="MENU" layoutX="152.0" layoutY="124.0" promptText="Username" />
<Button fx:id="abutton" layoutX="201.0" layoutY="227.0" mnemonicParsing="false" onAction="#Login" text="Login" />
<PasswordField fx:id="txtpassword" layoutX="152.0" layoutY="154.0" promptText="Password" />
<Label fx:id="db" layoutX="247.0" layoutY="41.0" text="status">
<font>
<Font size="15.0" />
</font>
</Label>
</children>
</AnchorPane>
我的 AddCustomer 类这里我还没有添加取消按钮的功能,只是想先检查“保存”按钮。
package sample;
import com.sun.istack.internal.NotNull;
import com.sun.istack.internal.Nullable;
import com.sun.org.apache.bcel.internal.generic.RETURN;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Alert;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
public class AddCustomer {
@FXML
public TextField number;
@FXML
public TextField name;
@FXML
public TextField stay;
@FXML
public TextField noofguests;
@FXML
public Button savebutton;
@FXML
public Button cancelbutton;
@FXML
@NotNull
@Nullable
public void addcustomer(ActionEvent actionEvent) throws Exception {
String customername = name.getText();
String customernumber = number.getText();
String customerstay = stay.getText();
String customerguests = noofguests.getText();
if (customername.isEmpty() || customerguests.isEmpty() || customernumber.isEmpty() || customerstay.isEmpty()) {
Alert alert = new Alert(Alert.AlertType.ERROR);
alert.setHeaderText(null);
alert.setContentText("PLEASE ENTER ALL THE FIELDS");
alert.show();
return;
}
String qu = "INSERT INTO CustomerDetails VALUES(" + "'" + customername + "'," +
"'" + customernumber + "'," +
"'" + customerstay + "'," +
"'" + customerguests + "'" + ")";
System.out.println(qu);
@NotNull
@Nullable
MysqlConnector mysqlConnector=new MysqlConnector();
try {
if (mysqlConnector.executeAction(qu)) {
@NotNull
@Nullable
Alert alert = new Alert(Alert.AlertType.INFORMATION);
alert.setHeaderText(null);
alert.setContentText("SUCCESS");
alert.show();
} else {
@NotNull
@Nullable
Alert alert = new Alert(Alert.AlertType.ERROR);
alert.setHeaderText(null);
alert.setContentText("FAILED");
alert.show();
}
}
catch(Exception e)
{ e.printStackTrace();}
}
public void cancel(ActionEvent actionEvent) {
}
}
我的添加客户 FXML
<?xml version="1.0" encoding="UTF-8"?>
<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.geometry.Insets?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.VBox?>
<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="599.0" xmlns="http://javafx.com/javafx/8.0.171" xmlns:fx="http://javafx.com/fxml/1" fx:controller="sample.AddCustomer">
<children>
<VBox layoutX="44.0" prefHeight="400.0" prefWidth="513.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="44.0" AnchorPane.rightAnchor="43.0" AnchorPane.topAnchor="0.0">
<children>
<TextField fx:id="name" prefHeight="50.0" prefWidth="492.0" promptText="Customer Name">
<VBox.margin>
<Insets bottom="10.0" left="10.0" right="10.0" top="30.0" />
</VBox.margin>
</TextField>
<TextField fx:id="number" layoutX="10.0" layoutY="10.0" prefHeight="53.0" prefWidth="492.0" promptText="Customer Number">
<VBox.margin>
<Insets bottom="10.0" left="10.0" right="10.0" top="10.0" />
</VBox.margin>
</TextField>
<TextField fx:id="stay" layoutX="10.0" layoutY="10.0" prefHeight="52.0" prefWidth="492.0" promptText="Stay Period ">
<VBox.margin>
<Insets bottom="10.0" left="10.0" right="10.0" top="10.0" />
</VBox.margin>
</TextField>
<TextField fx:id="noofguests" layoutX="10.0" layoutY="35.0" prefHeight="50.0" prefWidth="492.0" promptText="No. Of Guests">
<VBox.margin>
<Insets bottom="10.0" left="10.0" right="10.0" top="10.0" />
</VBox.margin>
</TextField>
<Button fx:id="savebutton" mnemonicParsing="false" onAction="#addcustomer" prefHeight="47.0" prefWidth="109.0" text="Save">
<VBox.margin>
<Insets bottom="10.0" left="100.0" right="10.0" top="10.0" />
</VBox.margin>
</Button>
<Button fx:id="cancelbutton" mnemonicParsing="false" onAction="#cancel" prefHeight="46.0" prefWidth="110.0" text="Cancel">
<VBox.margin>
<Insets bottom="10.0" left="300.0" right="10.0" top="-57.0" />
</VBox.margin>
</Button>
</children>
</VBox>
</children>
</AnchorPane>
请帮助修复此错误。
最佳答案
您收到此错误的原因是因为您尝试在从未初始化的 conn
上调用 conn.createStatement();
,因此 空
。
我看到您有一个名为 Connector()
的函数,它将初始化变量 conn
但您从未调用它,修复方法是调用 Connector ()
在 MysqlConnector
的构造函数中,然后再尝试对变量 conn
执行任何操作。
public MysqlConnector() {
conn = Connector();
if (conn != null) {
// Do your things here
}
}
关于JavaFX应用程序: Exception in thread "JavaFX Application Thread" java. lang.RuntimeException : java. lang.reflect.InitationTargetException,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/52913208/
我是 C 语言新手,我编写了这个 C 程序,让用户输入一年中的某一天,作为返回,程序将输出月份以及该月的哪一天。该程序运行良好,但我现在想简化该程序。我知道我需要一个循环,但我不知道如何去做。这是程序
我一直在努力找出我的代码有什么问题。这个想法是创建一个小的画图程序,并有红色、绿色、蓝色和清除按钮。我有我能想到的一切让它工作,但无法弄清楚代码有什么问题。程序打开,然后立即关闭。 import ja
我想安装screen,但是接下来我应该做什么? $ brew search screen imgur-screenshot screen
我有一个在服务器端工作的 UDP 套接字应用程序。为了测试服务器端,我编写了一个简单的 python 客户端程序,它发送消息“hello world how are you”。服务器随后应接收消息,将
我有一个 shell 脚本,它运行一个 Python 程序来预处理一些数据,然后运行一个 R 程序来执行一些长时间运行的任务。我正在学习使用 Docker 并且我一直在运行 FROM r-base:l
在 Linux 中。我有一个 c 程序,它读取一个 2048 字节的文本文件作为输入。我想从 Python 脚本启动 c 程序。我希望 Python 脚本将文本字符串作为参数传递给 c 程序,而不是将
对于一个类,我被要求编写一个 VHDL 程序,该程序接受两个整数输入 A 和 B,并用 A+B 替换 A,用 A-B 替换 B。我编写了以下程序和测试平台。它完成了实现和行为语法检查,但它不会模拟。尽
module Algorithm where import System.Random import Data.Maybe import Data.List type Atom = String ty
我想找到两个以上数字的最小公倍数 求给定N个数的最小公倍数的C++程序 最佳答案 int lcm(int a, int b) { return (a/gcd(a,b))*b; } 对于gcd,请查看
这个程序有错误。谁能解决这个问题? Error is :TempRecord already defines a member called 'this' with the same paramete
当我运行下面的程序时,我在 str1 和 str2 中得到了垃圾值。所以 #include #include #include using namespace std; int main() {
这是我的作业: 一对刚出生的兔子(一公一母)被放在田里。兔子在一个月大时可以交配,因此在第二个月的月底,每对兔子都会生出两对新兔子,然后死去。 注:在第0个月,有0对兔子。第 1 个月,有 1 对兔子
我编写了一个程序,通过对字母使用 switch 命令将十进制字符串转换为十六进制,但是如果我使用 char,该程序无法正常工作!没有 switch 我无法处理 9 以上的数字。我希望你能理解我,因为我
我是 C++ 新手(虽然我有一些 C 语言经验)和 MySQL,我正在尝试制作一个从 MySQL 读取数据库的程序,我一直在关注这个 tutorial但当我尝试“构建”解决方案时出现错误。 (我正在使
仍然是一个初学者,只是尝试使用 swift 中的一些基本函数。 有人能告诉我这段代码有什么问题吗? import UIKit var guessInt: Int var randomNum = arc
我正在用 C++11 编写一个函数,它采用 constant1 + constant2 形式的表达式并将它们折叠起来。 constant1 和 constant2 存储在 std::string 中,
我用 C++ 编写了这段代码,使用运算符重载对 2 个矩阵进行加法和乘法运算。当我执行代码时,它会在第 57 行和第 59 行产生错误,非法结构操作(两行都出现相同的错误)。请解释我的错误。提前致谢:
我是 C++ 的初学者,我想编写一个简单的程序来交换字符串中的两个字符。 例如;我们输入这个字符串:“EXAMPLE”,我们给它交换这两个字符:“E”和“A”,输出应该类似于“AXEMPLA”。 我在
我需要以下代码的帮助: 声明 3 个 double 类型变量,每个代表三角形的三个边中的一个。 提示用户为第一面输入一个值,然后 将用户的输入设置为您创建的代表三角形第一条边的变量。 将最后 2 个步
我是新来的,如果问题不好请见谅 任务:将给定矩阵旋转180度 输入: 1 4 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 输出: 16 15 14 13 12 11
我是一名优秀的程序员,十分优秀!