如何在JavaFX后台工作的GUI中进行更改？

Question

从所有的搜索和阅读中可以清楚地看出，我需要调用platform.runlater（）来更改GUI。似乎我还需要使用Runnable接口。也许我也应该使用任务？

但我不知道该怎么用。另外，我不确定我该把他们放到哪一个班。我是JavaFX的超级新手。

我的试用JavaFX项目只有一个Label和一个TextField。标签包含一个问题，而TextField用于回答问题。足够简单。

我遇到了这个问题：

答案检查方法在一个单独的类中。我不知道如何访问GUI/FXML的组件并更改它们。其他类中的方法是静态的，而GUI/FXML的组件是非静态的。

因为我的实际项目会有很多测验，所以我热衷于使用单独的类来检查答案。

这里只有3个小班是相关的：

null

package com.dan.ans;

import com.dan.qn.Qn;
import com.dan.view.ViewController;
public class Ans {
public static void checkAns() {

    // Checks if the ans is correct.
    if (ViewController.getTextFieldInput().equalsIgnoreCase(Qn.getAns())) {

        System.out.println("Correct!");     // Here I want the label to say 'Correct!' rather than it be print out in the console.

        Qn.setQuestion();                   // This gets the next question from the database. But again, I don't know how to make the changes show on the screen. (In the actual code I'd have a separate Label for each of these things)

    } else { // Runs if it's not correct.

        System.out.println("Incorrect!");    // Here I want the label to say 'Incorrect' rather than it be print out in the console.
    }
  }
}

package com.dan.view;

import java.io.IOException;
import java.net.URL;
import java.util.ResourceBundle;

import com.dan.ans.Ans;
import com.dan.qn.Qn;

import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;

public class ViewController implements Initializable {

private static String textFieldInput;      // I don't know how to access the typed info in the textField from another class. So I store it here and get it from it.

// This is the getter I use for it. (See above)
public static String getTextFieldInput() {
    return textFieldInput;
}

@FXML
private Label label;

@FXML
private TextField textField;

@Override
public void initialize(URL location, ResourceBundle resources) {

    Qn.setQuestion();                       // This method is in the Qn class. It retrieves data from the db file and keeps them in variables.

    label.setText(Qn.getQn());              // This sets the label's text using the retrieved data. So you see the first question when the program opens.
}

// Event Listener on TextField[#textField].onAction
public void enter(ActionEvent event) throws IOException {

    textFieldInput = textField.getText();    // Stores the typed info in the variable to be accessed from elsewhere.

    Ans.checkAns();                         // Runs the checkAns to check if the typed answer is correct or not.

  }

}

“Launcher”方法看起来就像任何带有主类的方法。所以我没有在这里分享它的代码。

有人能告诉我如何从其他类（如“ans”）更新GUI中的组件吗？我很确定应该使用platform.runlater（）和runnable。也可能是任务。我看过几个例子，但不清楚如何在上下文中使用它。

提前多谢了！：）

Answer 1

现在还不是很清楚这里的问题是什么。自然的方法（反正对我来说）就是让checkAnswer(...)方法成为一个简单的“按方框所说的做”的方法，即将答案作为参数，检查它，并向调用方返回一个值，以指示它是否正确。

这样还可以避免所有丑陋的静态攻击。

public class Ans {

    public boolean checkAns(String answer) {
        // not really sure what Qn is here, but you can also clean this up and
        // get rid of the static methods
        if (answer.equalsIgnoreCase(Qn.getAns()) {
            // not sure if this really belongs here?
            Qn.setQuestion(); // really takes no parameters? Sets it to what, then?
            return true ;
        } else {
            return false ;
        }
    }
}

然后在你的控制器里，你可以做

public class ViewController implements Initializable {

    private Ans ans ;

    @FXML
    private Label label;

    @FXML
    private TextField textField;

    @Override
    public void initialize(URL location, ResourceBundle resources) {

        ans = new Ans();
        // ...
    }

    // ...

    public void enter(ActionEvent event) {
        if (ans.checkAns(textField.getText())) {
            // update UI to show answer was correct, etc
        } else {
            // update UI to show answer was incorrect...
        }
    }

    // ...
}