Question

Hello I'm currently having an error that says "main is not abstract and does not override abstract method" is there a way to fix the error?

import java.io.IOException;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.stage.Stage;
import static javafx.application.Application.launch;
import javafx.scene.layout.StackPane;
public class Main extends Application implements EventHandler<ActionEvent>{
    public static void main(String[] args){
        launch(args);
    }
    @Override
    public void Start(Stage stage){
        stage.setTitle("Test");
        Button calcButton = new Button("Steam");
      
        StackPane root = new StackPane();
        calcButton.setOnAction(this);
      
        Scene scene = new Scene(root, 100, 100);
      
        stage.setScene(scene);
        stage.setTitle("Test");      
        stage.show();

    }
    class CalcButtonHandle {
      
        public void handle(ActionEvent event) throws IOException
        {
        Main fo = new Main();
        fo.runOt("D:\\Steam\\Steam.exe");
        }
    }
  
    public void runOt(String path) throws IOException{
        Runtime.getRuntime().exec("rundll32 url.dll,FileProtocolHandler " + path);
    }
}
  

Answer 1

If an interface is implemented by a class, it is necessary for the class to have function body for all the function definitions of the interface, unless the class is abstract or an interface itself.

The Main class implements EventHandler<ActionEvent> interface, therefore, it must also have the body of handle(ActionEvent event) function which is a function definition in EventHandler interface.

There was no need of a separate class CalcButtonHandle to wrap the handle() function. Below is the edited code (in bold), hope it helps!

Code:

import java.io.IOException;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.stage.Stage;
import static javafx.application.Application.launch;
import javafx.scene.layout.StackPane;
public class Main extends Application implements EventHandler<ActionEvent>{
    public static void main(String[] args){
        launch(args);
    }
    @Override
    public void Start(Stage stage){
        stage.setTitle("Test");
        Button calcButton = new Button("Steam");
      
        StackPane root = new StackPane();
        calcButton.setOnAction(this);
      
        Scene scene = new Scene(root, 100, 100);
      
        stage.setScene(scene);
        stage.setTitle("Test");      
        stage.show();

    }

    public void handle(ActionEvent event) throws IOException
{
        Main fo = new Main();
        fo.runOt("D:\\Steam\\Steam.exe");
    }
  
    public void runOt(String path) throws IOException{
        Runtime.getRuntime().exec("rundll32 url.dll,FileProtocolHandler " + path);
    }
}