Why my random number cannot randomly display?

1. For Addition and Subtraction questions, both numbers should be no more than 100.
2. For Multiplication, both numbers should not be more than 12.
3. For Division, the first number should not be more than 100, and the second number of the question should not be more than 10.

Why my random number cannot randomly display?

Here is my code below.

HERE is my CODE

import javax.swing.*;
import java.awt.event.*;
import java.awt.*;

public class aaa implements ActionListener{
static JFrame frame;
static JPanel panelCenter,panelBottom,panelHead;
static JLabel Score,Fnumber,operator,Snumber,equals;
static JTextField Type,Answer;
static JButton btnNext;
static int c,d;

public static void main(String[] args){
frame = new JFrame("Mathematics Game");
frame.setSize(350,280);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setLayout(new GridLayout(4,1));
createInterface();

frame.setVisible(true); 
}

public static void createInterface(){
panelHead = new JPanel();
panelHead.setLayout(new FlowLayout(FlowLayout.CENTER));
Score = new JLabel("Scoring Mode");

panelCenter = new JPanel();
panelCenter.setLayout(new FlowLayout(FlowLayout.CENTER));
Fnumber = new JLabel();
operator = new JLabel();
Snumber = new JLabel();
equals = new JLabel("=");
Type = new JTextField(20); 

panelBottom = new JPanel();
Answer = new JTextField(20);

Answer.setEditable(false);

btnNext = new JButton("Next");
btnNext.addActionListener(new aaa());

panelHead.add(Score);
panelCenter.add(Fnumber);
panelCenter.add(operator);
panelCenter.add(Snumber);
panelCenter.add(equals);
panelCenter.add(Type);
panelBottom.add(Answer);

frame.add(panelHead);
frame.add(panelCenter);
frame.add(panelBottom);
frame.add(btnNext); 
}

public static int randomNumber(int min, int max){
int rand = (int) (Math.random() * (max - min + 1)) + min;

return rand;
}

@Override
public void actionPerformed(ActionEvent e){
if(e.getSource() == btnNext){
int opt = randomNumber(1,4);
operator.setText(String.valueOf(randomNumber(1,4)));

c = Integer.parseInt(Fnumber.getText());
d = Integer.parseInt(Snumber.getText());

if(opt == 1){           
operator.setText("+");
Fnumber.setText(String.valueOf(randomNumber(1,100)));
Snumber.setText(String.valueOf(randomNumber(1,100)));
String i=String.valueOf(c+d);
Answer.setText(i);
}else if(opt == 2){
operator.setText("-");
Fnumber.setText(String.valueOf(randomNumber(1,100)));
Snumber.setText(String.valueOf(randomNumber(1,100)));
String i=String.valueOf(c-d);
Answer.setText(i);
}else if(opt == 3){
operator.setText("*");  
Fnumber.setText(String.valueOf(randomNumber(1,12)));
Snumber.setText(String.valueOf(randomNumber(1,12)));
String i=String.valueOf(c*d);
Answer.setText(i);
}else if(opt == 4){
operator.setText("/");
Fnumber.setText(String.valueOf(randomNumber(1,100)));
Snumber.setText(String.valueOf(randomNumber(1,10)));
String i=String.valueOf(c/d);
Answer.setText(i);
}   
}

}
}