I am making a ping pong game using JavaFX, but before I am going to make that, I like to test the KeyEvents.
I made a simple ping pong game about 2 years ago, but I like to improve my game.
And was pretty bad controlls back when I made the ping pong game, because of the not smooth controls.

so here is the problem:
whenever I holdpress A and switch quickly to holdpress D or D to A, same with (W to S and S to W).
it just takes a little break and then move, is there something I can change, improve?
I don't know why it does this.

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If you start to press the next key before you have fully released the previous one then the release will override the press. Maybe that's part of the problem???

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//here is my code

import javafx.animation.AnimationTimer;
import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;

public class SmoothKeyEvents extends Application {

    public final static String TITLE = "simple key-input program";
    public final static short WIDTH = 1280;
    public final static short HEIGHT = 720;

    private Stage window;
    private Scene mainS;
    private Group groupS;
    private Rectangle rect;

    private int x = 50;
    private int y = 50;
    private int velX = 0;
    private int velY = 0;

    @Override
    public void start(Stage primaryStage) {
        groupS = new Group();
        mainS = new Scene(groupS, WIDTH, HEIGHT, Color.DARKBLUE);
        window = primaryStage;
        window.setScene(mainS);
        window.setTitle(TITLE);
        window.show();
        window.requestFocus();

        rect = new Rectangle();
        rect.setFill(Color.MEDIUMSPRINGGREEN);
        rect.setX(x);
        rect.setY(y);
        rect.setWidth(150);
        rect.setHeight(150);
        groupS.getChildren().add(rect);

        mainS.setOnKeyPressed(new EventHandler<KeyEvent>(){

            @Override
            public void handle(KeyEvent ke) {
                if(ke.getCode() == KeyCode.A) {
                    setVelX(-9);
                }
                if(ke.getCode() == KeyCode.S) {
                    setVelY(9);
                }
                if(ke.getCode() == KeyCode.D) {
                    setVelX(9);
                }
                if(ke.getCode() == KeyCode.W) {
                    setVelY(-9);
                }
            }
        });

        mainS.setOnKeyReleased(new EventHandler<KeyEvent>(){

            @Override
            public void handle(KeyEvent ke) {
                if(ke.getCode() == KeyCode.A) {
                    setVelX(0);             
                }
                if(ke.getCode() == KeyCode.S) {
                    setVelY(0);
                }
                if(ke.getCode() == KeyCode.D) {
                    setVelX(0);
                }
                if(ke.getCode() == KeyCode.W) {
                    setVelY(0);
                }
            }
        });

        final AnimationTimer at = new AnimationTimer() {

            @Override
            public void handle(long arg0) {
                x += velX;
                rect.setX(x);
                y += velY;
                rect.setY(y);
            }
        };
        at.start();
    }

    public void setVelX(int velX) {
        this.velX = velX;
    }

    public void setVelY(int velY) {
        this.velY = velY;
    }

    public void stop() {
        System.out.println("program exited");
    }

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

If you start to press the next key before you have fully released the previous one then the release will override the press. Maybe that's part of the problem???

yes, that is the problem

nvm, my keys already are smooth enough XD
I am dumb, this is a dumb post, I facepalmed myself.

commented: Smooth. Don't laugh. Optimizing too much is a thing. I was going to comment about something then I see you already did it so you're fine. Good going. +15