I want to change this code from human vs human player to human vs computer player !

the whole code won't fit in here

i included the important code to change

JavaFx language Please !

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import javafx.event.ActionEvent;

import javafx.event.EventHandler;

import javafx.geometry.Insets;

import javafx.scene.Scene;

import javafx.scene.control.Button;

import javafx.scene.layout.GridPane;

import javafx.stage.Stage;

public class GameBoard {

private boolean alternateTurn = false;

private Button[] buttons = new Button[9];

private int counter = 0;

private Stage stage;

private Scene scene;

public GameBoard(Stage stage) {

createOrganizeAndAssignActionToButtons(buttons);

GridPane gridPane = new GridPane();

gridPane.setPadding(new Insets(20));

int counter = 0;

for (int i = 0; i < 3; i++) {

for (int j = 0; j < 3; j++) {

if (counter > 8) {

break;

}

gridPane.add(buttons[counter], i, j);

counter++;

}

}

scene = new Scene(gridPane, 230, 230);

stage.setScene(scene);

stage.show();

stage.setResizable(false);

this.stage = stage;

}

private void createOrganizeAndAssignActionToButtons(Button[] buttons) {

for (int i = 0; i < 9; i++) {

Button button = new Button();

buttons[i] = button;

button.setPrefWidth(80);

button.setMaxWidth(80);

button.setPrefHeight(80);

button.setMaxHeight(80);

changeTurn(button);

}

}

public Button[] getButtons() {

return buttons;

}

private void changeTurn(Button button) {

button.setOnAction(new EventHandler() {

@Override

public void handle(ActionEvent arg0) {

String winnerString = "";

if (button.getText().isEmpty()) {

if (!alternateTurn) {

button.setText("X");

alternateTurn = true;

} else {

button.setText("O");

alternateTurn = false;

}

winnerString = button.getText();

counter++;

}

// first column

if (buttons[0].getText().equals(winnerString) && buttons[1].getText().equals(winnerString)

&& buttons[2].getText().equals(winnerString) ||

// second column

buttons[3].getText().equals(winnerString) && buttons[4].getText().equals(winnerString)

&& buttons[5].getText().equals(winnerString) ||

// third column

buttons[6].getText().equals(winnerString) && buttons[7].getText().equals(winnerString)

&& buttons[8].getText().equals(winnerString) ||

// first row

buttons[0].getText().equals(winnerString) && buttons[3].getText().equals(winnerString)

&& buttons[6].getText().equals(winnerString) ||

// second row

buttons[1].getText().equals(winnerString) && buttons[4].getText().equals(winnerString)

&& buttons[7].getText().equals(winnerString) ||

// third row

buttons[2].getText().equals(winnerString) && buttons[5].getText().equals(winnerString)

&& buttons[8].getText().equals(winnerString) ||

// first diagonal

buttons[0].getText().equals(winnerString) && buttons[4].getText().equals(winnerString)

&& buttons[8].getText().equals(winnerString) ||

// second diagonal

buttons[2].getText().equals(winnerString) && buttons[4].getText().equals(winnerString)

&& buttons[6].getText().equals(winnerString)) {

PopUp popup = new PopUp(stage);

popup.setMessage(winnerString + " wins");

} else if (counter >= 9) {

PopUp popup = new PopUp(stage);

popup.setMessage("Draw... ");

}

}

});

}

}