import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.geometry.Rectangle2D;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.input.MouseEvent;
import javafx.stage.Stage;

public class Test extends Application {
    public void start(Stage stage) {
        final Image missingimg = new Image("http://wjpijpijpqwef.com/foo.png");
        Image goodimg = new Image("car.png");
        ImageView iv = new ImageView(goodimg);
        iv.setViewport(new Rectangle2D(5, 5, 20, 20));
        iv.setX(100);
        iv.setY(100);
        iv.setFitWidth(100);
        iv.setFitHeight(100);

        Scene scene = new Scene(new Group(iv), 500, 500);
        scene.addEventHandler(MouseEvent.MOUSE_PRESSED, new EventHandler<MouseEvent>() {
            public void handle(MouseEvent event) {
                iv.setImage(missingimg);
            }
        });

        stage.setScene(scene);
        stage.show();
    }
}