shar_img_gif.setVisible(true);
    Thread s1 = new Thread(new Runnable(){
        public void run(){
            try {
                Thread.sleep(1000);
                shar_img_gif.setVisible(false);
                int i = (int)(Math.random()*o.x);
                shar_otv1.setText(o.otv[i]);
                shar_vopros.setText(shar_text.getText()+"?");
                shar_text.setText(null);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    });
    s1.start();

shar_otv1.setText(o.otv[i]);
shar_vopros.setText(shar_text.getText()+"?");

shar_img_gif.setVisible(true);
Thread timer = new Timer(1000/*Time in millis*/,e->
{
    Platform.runLater(()->
    {
        shar_img_gif.setVisible(false);
        int i = (int)(Math.random()*o.x);
        shar_otv1.setText(o.otv[i]);
        shar_vopros.setText(shar_text.getText()+"?");
        shar_text.setText(null);
    }/*Runnable*/);
}/*ActionListener*/);
timer.setRepeats(false);
timer.start();

Platform.runLater(()->
{
    //Your code there
});