我现在正在研究JavaFX应用程序。我的所有GUI都是.fxml
格式,并且通过 Controller 类管理所有GUI组件。但是,在加载FXML加载程序之前,我很难用实例化 Controller 类。我无法从其他关于stackoverflow的问题中找到一个好的解决方案,因此这不是重复的问题。
我实例化 Controller 类的原因是我想传递一些参数,以便这些参数将显示在GUI中。
我通过以下方式加载FXML文件:
/*
* for Work Order button
*/
@FXML
private void pressWorkOrder() throws Exception{
WorkOrderController wo = new WorkOrderController("ashdkjhsahd"); //instantiating constructor
Parent parent = FXMLLoader.load(getClass().getResource("/fxml/WorkOrder.fxml"));
Scene scene = new Scene(parent);
Stage stage = new Stage();
stage.setScene(scene);
stage.setTitle("Word Order");
stage.setResizable(false);
stage.show();
}
这是我实际的Controller类:
public class WorkOrderController implements Initializable{
@FXML
private Button summary;
private String m,n;
public WorkOrderController(String str) {
// TODO Auto-generated constructor stub
m = str;
}
//for testing
public void set(String str){
m = str;
}
@FXML
public void check(){
System.out.println("Output after constructor was initialized " + m);
}
@Override
public void initialize(URL location, ResourceBundle resources) {
// TODO Auto-generated method stub
}
}
我得到这个异常:
at javafx.fxml.FXMLLoader.processStartElement(Unknown Source)
at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml.FXMLLoader.load(Unknown Source)
at MainController.pressWorkOrder(MainController.java:78)
... 57 more
Caused by: java.lang.InstantiationException: WorkOrderController
at java.lang.Class.newInstance(Unknown Source)
at sun.reflect.misc.ReflectUtil.newInstance(Unknown Source)
... 71 more
Caused by: java.lang.NoSuchMethodException: WorkOrderController.<init>()
at java.lang.Class.getConstructor0(Unknown Source)
... 73 more
最佳答案
对于小型应用程序,最简单的两种方法是:
fx:controller
。通过将数据传递给它来创建一个 Controller 实例,然后将其传递给FXMLLoader。 fx:controller
。从FXMLLoader获取 Controller 实例,然后将数据传递给 Controller 。 以下是上述两种类型的示例。每个示例都有3个组成部分:
doesn't have
声明进行fx:controller
,对第二种类型进行声明。 constructor
。第二种类型具有setter methods
。 sets the controller to FXMLLoader
。在第二秒,它是fetches the controller from the FXMLLoader
。 1.手动创建 Controller 实例
FXML -不指定fx:controller
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.layout.FlowPane?>
<?import javafx.scene.control.Label?>
<FlowPane fx:id="root" xmlns:fx="http://javafx.com/fxml">
<children>
<Label fx:id="firstName" text="" />
<Label fx:id="lastName" text="" />
</children>
</FlowPane>
Controller -创建一个构造函数以接受默认值
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Label;
import java.net.URL;
import java.util.ResourceBundle;
public class SampleController implements Initializable {
private StringProperty firstNameString = new SimpleStringProperty();
private StringProperty lastNameString = new SimpleStringProperty();
/**
* Accepts the firstName, lastName and stores them to specific instance variables
*
* @param firstName
* @param lastName
*/
public SampleController(String firstName, String lastName) {
firstNameString.set(firstName);
lastNameString.set(lastName);
}
@FXML
Label firstName;
@FXML
Label lastName;
@Override
public void initialize(URL location, ResourceBundle resources) {
firstName.setText(firstNameString.get());
lastName.setText(lastNameString.get());
}
}
主-创建一个Controller实例,方法是将值传递给它,然后将其传递给FXMLLoader
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.layout.FlowPane;
import javafx.stage.Stage;
public class Main extends Application {
@Override
public void start(Stage primaryStage) throws Exception {
FXMLLoader loader = new FXMLLoader(getClass().getResource("Sample.fxml"));
// Create a controller instance
SampleController controller = new SampleController("itachi", "uchiha");
// Set it in the FXMLLoader
loader.setController(controller);
FlowPane flowPane = loader.load();
Scene scene = new Scene(flowPane, 200, 200);
primaryStage.setScene(scene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
2.从FXMLLoader获取 Controller 实例
FXML -已指定fx:controller
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.layout.FlowPane?>
<?import javafx.scene.control.Label?>
<!-- Controller Specified -->
<FlowPane fx:id="root" xmlns:fx="http://javafx.com/fxml" fx:controller="SampleController">
<children>
<Label fx:id="firstName" text="" />
<Label fx:id="lastName" text="" />
</children>
</FlowPane>
Controller -具有Setter方法来接受输入
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Label;
import java.net.URL;
import java.util.ResourceBundle;
public class SampleController implements Initializable {
@FXML
Label firstName;
@FXML
Label lastName;
@Override
public void initialize(URL location, ResourceBundle resources) {
}
/**
* Accepts a String and sets it to the firstName Label
*
* @param firstNameString
*/
public void setFirstName(String firstNameString) {
firstName.setText(firstNameString);
}
/**
* Accepts a String and sets it to the lastName Label
*
* @param lastNameString
*/
public void setLastName(String lastNameString) {
lastName.setText(lastNameString);
}
}
主要-调用
load()
之后从FXMLLoader获取Controller实例,然后调用setter方法以传递数据。import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.layout.FlowPane;
import javafx.stage.Stage;
public class Main extends Application {
@Override
public void start(Stage primaryStage) throws Exception {
FXMLLoader loader = new FXMLLoader(getClass().getResource("Sample.fxml"));
FlowPane flowPane = loader.load();
// Get the Controller from the FXMLLoader
SampleController controller = loader.getController();
// Set data in the controller
controller.setFirstName("itachi");
controller.setLastName("uchiha");
Scene scene = new Scene(flowPane, 200, 200);
primaryStage.setScene(scene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
关于javafx - JavaFX:在实例化 Controller 类时传递参数,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/30814258/