Minesweeper Mines no se colocará ni aparecerá [cerrado]

Why will this code not load buttons when run? The question is very vague I know but I'm very new to Java and trying to understand lots of things at once. This code is based off of my two previous successful attempts to code TicTacToe and Connect Four both of which worked.

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.applet.Applet;
import java.awt.event.ActionListener;

public class Minesweeper extends Applet implements ActionListener {
    // initializing all data types

    JButton[] a; // The grid boxes
    int counter = 1; // Obsolete
    char[] letter; // Array of mine locations
    int[] numbers; // Array of numbers; values and locations
    boolean explode = false;
    String name1;
    String name2;
    int mines;

    public void init() {
        // The code below initializes and locates the grid
        setLayout(new GridLayout(10, 10));
        a = new JButton[100];
        // The code below fills the grid with buttons that can be clicked

        for (int counter = 0; counter < 100; counter++) {
            a[counter] = new JButton();
            a[counter].setText(" ");
            a[counter].setBackground(Color.white);
            a[counter].addActionListener(this);
            add(a[counter]);
        }

    }

    public void nit() {

        numbers = new int[100];
        letter = new char[100];
        for (counter = 0; counter < 10; counter++) {
            mines = (int) Math.random() * 100;
            if (letter[mines] == '*') {
                counter--;
            } else {
                letter[mines] = '*';
            }
        } 

        for (counter = 0; counter < 100; counter++) {
            numbers[counter] = 0;
        }

        for (int search = 0; search < 10; search++) {
            for (int searchb = 0; searchb < 10; searchb++) {
                if (letter[search * 10 + searchb] == '*') {
                    if (search != 0) {
                        numbers[((search - 1) * 10) + searchb]++;
                    }
                    if (search != 9) {
                        numbers[((search + 1) * 10) + searchb]++;
                    }
                    if (searchb != 0) {
                        numbers[((search * 10) + searchb) - 1]++;
                    }
                    if (searchb != 9) {
                        numbers[((search * 10) + searchb) + 1]++;
                    }
                    if ((search != 0) && (searchb != 0)) {
                        numbers[(((search - 1) * 10) + searchb) - 1]++;
                    }
                    if ((search != 9) && (searchb != 9)) {
                        numbers[(((search + 1) * 10) + searchb) + 1]++;
                    }
                    if ((search != 0) && (searchb != 9)) {
                        numbers[(((search - 1) * 10) + searchb) + 1]++;
                    }
                    if ((search != 9) && (searchb != 0)) {
                        numbers[(((search + 1) * 10) + searchb) - 1]++;
                    }

                }

            }

        }
        for (int counter = 0; counter < 100; counter++) {
            letter[counter] = (char) ('0' + numbers[counter]);
            JOptionPane.showMessageDialog(null, " " + letter[counter]);
        }
    }

    // ActionEvent e is the click
    public void actionPerformed(ActionEvent e) {
        int pickedsquare = 0, coloring, pickedcolumn = 0;
        JButton b = (JButton) e.getSource();
        counter++;
        b.setText("Test");
        for (int f = 0; f < 100; f++) {
            JOptionPane.showMessageDialog(null, " " + letter[f]);
            if (a[f].getText() == "Test") {
                pickedsquare = f;
                JOptionPane.showMessageDialog(null, " " + letter[f]);
                name1 = " " + letter[pickedsquare];
                a[f].setText(name1);
                break;
            }
        }
        if (letter[pickedsquare] == '*')
            explode = true;

        if (explode == true) {
            JOptionPane.showMessageDialog(null, "You are dead!");
            for (int counterb = 0; counterb <= 99; counterb++) {
                a[counterb].setEnabled(false);

            }
        }

        if (counter == 89) {
            JOptionPane.showMessageDialog(null, "You have swept all mines!");
            for (int counterb = 0; counterb <= 99; counterb++) {
                a[counterb].setEnabled(false);

            }
        }
    } 
}