Java 按钮事件处理

Question

我的任务是制作一款名为“猜数字”的游戏。用户猜测一个介于 1 和 1000 之间的数字，单击“确定”并收到一条消息，说明它是否正确、过高或过低。我的问题是事件处理。当我按下“确定”时，程序会崩溃。我做错了什么？

package application;

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;

public class GjettTalletSpill extends Application implements EventHandler<ActionEvent> {

Button ok;
Label text;
Label message;
TextField TF;

public static void main(String[] args) {
    launch(args);


}// Main.

@Override
public void start(Stage primaryStage) throws Exception {
    primaryStage.setTitle("Gjett tallet spill");

    ok = new Button("OK");
    ok.setOnAction(this);
    ok.setPrefSize(100,20);
    text = new Label("Guess a number between 1 and 1000: ");
    TF = new TextField();
    message = new Label("");

    GridPane gp = new GridPane();

    gp.add(text,1,1);
    gp.add(TF,3,1);
    gp.add(message,2,2);
    gp.add(ok,2,3);

    Scene scene = new Scene(gp,600,150);
    primaryStage.setScene(scene);
    primaryStage.show();

}


@Override 
public void handle(ActionEvent event) {

    int uGuessed;
    int theNumber;

    tallet = 1 + (int)(Math.random() * 1000); 
    uGuessed = Integer.parseInt(TF.getText());

    while (uGuessed != theNumber){

        if (uGuessed<theNumber){
            message.setText("The number was too low. Try again!");
        } else {
            message.setText("The number was too high. Try again!");

        }// if/else.
    }// while.

    message.setText("Congratulations! You guessed the roght number! :D");
}// ActionEvent.

}// Class.

Answer 1

您的程序当然会冻结。当您按下按钮时，您的程序会调用句柄函数并且永远不会返回（除非您在第一次尝试时输入了正确的数字）。所以你的程序在处理事件时卡住了，e。 G。不会再调用repaint-method了。

只需删除 while 循环。请记住，每次按下确定按钮时都会调用您的句柄方法。所以不要在句柄方法中生成你的随机数。移动

private int theNumber;
    @Override
    public void start(Stage primaryStage) throws Exception {
        theNumber = 1 + (int) (Math.random() * 1000);

在您的启动方法之上，在您启动应用程序后生成一个随机数。

并替换您的 Action 处理程序，使其只检查一次数字，更新消息标签然后返回。

@Override
    public void handle(ActionEvent event) {
        int uGuessed;
        uGuessed = Integer.parseInt(TF.getText());

        if (uGuessed < theNumber) {
            message.setText("The number was too low. Try again!");
        } else if (uGuessed > theNumber) {
            message.setText("The number was too high. Try again!");
        } else {
            message.setText("Congratulations! You guessed the roght number! :D");
        } // ActionEvent.
    }

你的程序应该可以工作:)。