Question

import javafx.application.Application;
import javafx.geometry.Insets;
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 abstract class login extends Application
{
    Stage window;
    public static void main(String arvg[])
    {
        launch(arvg);
    }
    @Override
    public void start(Stage primaryStage) throws Exception
    {
        window= primaryStage;
        window.setTitle("Login");

        GridPane grid=new GridPane();
        grid.setPadding(new Insets(10,10,10,10));
        grid.setVgap(8);
        grid.setHgap(8);

        //Label1
        Label lbl1=new Label("User Name");
        GridPane.setConstraints(lbl1,0,0);

        //label2
        Label lbl2=new Label("Password");
        GridPane.setConstraints(lbl2,0,1);

        //userinput
        TextField username=new TextField();
        username.setPromptText("UserName");
        GridPane.setConstraints(username,1,0);

        //Password
       TextField password=new TextField();
        password.setPromptText("Password");
        GridPane.setConstraints(password,1,1);

        //login
        Button button=new Button("Log In");
        GridPane.setConstraints(button,0,2);

        grid.getChildren().addAll(lbl1,lbl2,username,password,button);
        Scene s=new Scene(grid,300,200);
        window.setScene(s);
        window.show();

    }
}

这是一个登录页面。当我尝试运行它时，它在Application构造函数中显示Exception，并在线程“main”中出现很多错误，例如异常java.lang.RuntimeException：无法构造Application实例：class login 在com.sun.javafx.application.LauncherImpl.launchApplication1（LauncherImpl.java:907） at com.sun.javafx.application.LauncherImpl.lambda $ launchApplication $ 155（LauncherImpl.java:182）在java.lang.Thread.run（Thread.java:745）我不知道是什么问题。那么任何人都可以解释或帮助我解决它？感谢。

Answer 1

为什么要让课程抽象化？如果它是抽象的，应用程序将无法从类中创建对象。从类定义中删除abstract关键字。

当我运行它时，它在Application构造函数中显示Exception

1 个答案: