multiple objects of the same class "Minesweeper" - minesweeper

Question

im new in java and my question might be stupid but i really dont know how to solve this problem, im making a Minesweeper and im using javafx, im using a class for the mines, so im using a "stackPane" and im puting it inside a grid, the problem i have is that i don't know hot to make multiples instances of it, and i have no clue how to start, im makinga 10*10 board and the mines are suposed to apear randomly, so im using "math.random" to decide if one space will be empti or if it will have a mine, i hope some one out there can help me
well i find a solution, but the thing i dont know how to do now is how to set a "setaction" for each button, im trying to put setonactio(new eventhandler() ...
here is my code:
package buscaminas2;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.layout.FlowPane;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
/**
*
* #author ALIENWARE R4
*/
public class Buscaminas2 extends Application {
#Override
public void start(Stage primaryStage) {
primaryStage.setTitle("buscaminas");
GridPane mainGrid = new GridPane();
GridPane flowPane = new GridPane();
flowPane.setPadding(new Insets(2, 2, 2, 2));
flowPane.setVgap(2);
flowPane.setHgap(2);
//flowPane.setPrefWrapLength(210);
HBox score = new HBox();
Button btn = new Button();
for (int i = 0; i < 10; i++) {//-----------------bob the constructor------------------//
for (int j = 0; j < 10; j++)
{
int abc = (int)(Math.random()*10);
System.out.print(abc);
if( abc > 2)
{
btn = new Button(" ");
btn.setId(STYLESHEET_MODENA);
btn.setPrefSize(35, 35);
flowPane.add(btn, i, j);
flowPane.getChildren().get(i);
}
else
{
StackPane boomb = new StackPane();//---------------------bombs--------------------//
boomb.setPrefSize(35, 35);
Label num = new Label("X");
num.setPrefSize(40, 40);
boomb.getChildren().add(num);
Button xyz = new Button();
xyz.setPrefSize(40, 40);
boomb.getChildren().add(xyz);
flowPane.add(boomb, i, j);// agrega bombas en xy agregando "boomb" en el grid
}
}
}
Scene scene = new Scene(flowPane);
primaryStage.setScene(scene);
primaryStage.show();
}
}