JavaFX 中具有静态引用的静态按钮的 java.lang.NullPointerException

Question

好吧，我有一个难题。我有一个 Qaurtz Cron，我想用它来安排和运行一些 Java 测试。这些任务是通过使用 JavaFX 的 GUI 来安排的。但是，作业本身调用运行测试方法。这项工作迫使我将某些元素设为静态，但通过将它们设为静态，我得到了空指针异常。我真的很感激这里的一些帮助。

所以这是强制事物静态的作业类。

public class newJob implements Job{

    public void execute(JobExecutionContext arg0) throws JobExecutionException {
        System.out.println("We are attempting the job now");
        try {
            FXMLDocumentController.runScheduledTests();
        } catch (Throwable e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

在我的 Controller 中我有这样的东西:

public static void runTests() throws SQLException, IOException {
        // Set running to true. In current form we do not use this bool,
        // however, we may
        // make changes that rely on this.
        running = true;
        FileOutputStream fos = null;
        // Verify that users exist, and there is a url with the word max in it
        int count = DBHelpers.getResults("SELECT * FROM USERS;", new String[] { "ID" }).length();

        // Verify that we have both users and a maximo url to work with.
        if ((!userList.isEmpty() || count > 0) && userMaxListChoice.length() > 5) {

            // Set the proper driver, default to chrome if none is selected
            if (IEbutton.isSelected()) {
                BrowserConfig.setDriver(Browsers.IE());
            } else {
                BrowserConfig.setDriver(Browsers.Chrome());
            }

            // Let's assign maximo. If no one has clicked the use UserList
            // button, assume that the data inside
            // maximo name is good to use
            if (userMaxListChoice != null) {
                BrowserConfig.setMaximo(userMaxListChoice);
                // System.out.println("used maxLIst choice");
            } else {
                // If the user has not selected a name from the maximo list,
                // let's grab whatever
                // they have entered in the maximoName field.
                BrowserConfig.setMaximo(maximoName.getText());
            }

            // Set the system pause based on the interval string
            int pause = Integer.parseInt(interval.getText().toString());
            // Make sure the puase is in miliseconds
            pause = pause * 1000;
            BrowserConfig.setInterval(pause);

请注意，runScheduledTests() 方法会进行一些配置并调用 runTest 方法。在运行测试方法内部，我遇到了错误，特别是这一行:

if (IEbutton.isSelected()) {
                BrowserConfig.setDriver(Browsers.IE());
            } else {
                BrowserConfig.setDriver(Browsers.Chrome());
            }

原因是上面我有这个:

@FXML
    public static RadioButton ChromeButton;

    @FXML
    public static RadioButton IEbutton;

正如我所说，这是一个问题，如果我不将它们设为静态，作业类就会因为我进行非静态引用而对我大喊大叫。

如何解决此冲突？

Answer 1

TL;DR:您不应在使用 @FXML 注释的字段上使用 static。

欲了解更多信息，请访问 - javafx 8 compatibility issues - FXML static fields

您可以使用 FXMLLoader 加载 FXML，然后从中获取 Controller 的实例。通过这样做，您可以将方法 runScheduledTests() 转换为非静态方法。

public class newJob implements Job{

    public void execute(JobExecutionContext arg0) throws JobExecutionException {
        try {
            FXMLLoader fxmlLoader = 
                        new FXMLLoader(getClass().getResource("path-to-fxml.fxml"));
            fxmlLoader.load();
            FXMLDocumentController fxmlDocumentController = 
                        (FXMLDocumentController)fxmlLoader.getController();
            fxmlDocumentController.runScheduledTests(); // convert the method to non-static
        } catch (Throwable e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}