Passgen.java

import javax.swing.*;
import javax.swing.UIManager;
import javax.swing.border.*;
import java.awt.Font;
import java.security.SecureRandom;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.datatransfer.*;
import java.awt.Toolkit;
import java.awt.Color;

public class PasswordGenerator {
    public static void main(String[] args) {
        Window w = new Window();
    }
}

class Window extends JFrame { // Extend Windows from Jframe
    private int length;
    private boolean nrIsSet = false;
    private boolean dark = false;
    //private int[] bgcolour = {255,255,255};    //Dark mode : TO DO
    //private int[] kek = {255,255,255};
    private int input = 1;

    Window() {

        //defining basic parameters of our Window
        UIManager UI = new UIManager(); // Dark mode
        setLayout(null);
        setSize(500, 300);
        setTitle("Password Generator");
        setVisible(true);
        setResizable(false);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        Color font_white = new java.awt.Color(84, 84, 84);
        Color co_dark = new java.awt.Color(49, 49, 49);
        Color font_dark = new java.awt.Color(148, 148, 148);


        // Create JTextField component where we want to input number of characters and read output (password
        JTextField textField = new JTextField("Enter length of password");
        textField.addMouseListener(new MouseAdapter() {// This Listener makes the initiate text dissapear on click
            @Override
            public void mouseClicked(MouseEvent e) {
                nrIsSet = false;
                if (!nrIsSet) {
                    textField.setText("");
                }
            }
        });
        //Setting parameters of our Password Field
        Font font1 = new Font("Monoid", Font.BOLD, 13);
        textField.setForeground(font_white);
        textField.setCaretColor(font_white);
        textField.setFont(font1);
        textField.setSize(475, 50);
        textField.setLocation(10, 50);
        JTextField tf = new JTextField();
        textField.setVisible(true);
        textField.setHorizontalAlignment(JTextField.CENTER);

        //Creating generate button
        JButton generateButton = new JButton("Generate");
        generateButton.setLocation(145, 120);
        generateButton.setSize(100, 38);
        generateButton.setVisible(true);
        generateButton.setForeground(font_white);

        //ActionListener starts listening to activites
        generateButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                System.out.println(isNumeric(textField.getText()));
                //Force the necessity of another click for another input for password
                if (!nrIsSet) {
                    //Check if the input we recieved is valid int or not
                    //If not valid then give a hint about the same
                    if (isNumeric(textField.getText())) {
                        length = Integer.parseInt(textField.getText());
                        nrIsSet = true;
                    } else {
                        textField.setText("Invalid input, Provide the length of password in digits.");
                    }
                }
                //Finally a basic check if input isn't null
                if (length != 0) {
                    String pswd = new String(genPass(length));
                    textField.setText(pswd);

                }
            }
        });
        //Copy button which makes it easy to copy the password using only one button.
        JButton copyToClipboardButton = new JButton("Copy");
        copyToClipboardButton.setSize(100, 38);
        copyToClipboardButton.setLocation(255, 120);
        copyToClipboardButton.setVisible(true);
        copyToClipboardButton.setForeground(font_white);
        copyToClipboardButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                //check if the user didn't change the input again for new password.
                if (textField.getText().length() == length) {
                    StringSelection stringSelection = new StringSelection(textField.getText());
                    Clipboard clpbrd = Toolkit.getDefaultToolkit().getSystemClipboard();
                    clpbrd.setContents(stringSelection, null);
                }
            }
        });

        JToggleButton DMButton = new JToggleButton("Dark mode");
        DMButton.setSize(90, 38);
        DMButton.setLocation(390, 220);
        DMButton.setVisible(true);
        DMButton.setForeground(font_white);
        DMButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                Object[] options = {"Yes",
                        "No"};
                if (!dark) {
                    UI.put("OptionPane.messageForeground", font_white);
                    UI.put("OptionPane.background", new java.awt.Color(255, 255, 255));
                    UI.put("Panel.background", new java.awt.Color(255, 255, 255));
                    input = JOptionPane.showOptionDialog(null,
                            "Would you like to enable dark mode?",
                            "Dark mode",
                            JOptionPane.YES_NO_OPTION,
                            JOptionPane.QUESTION_MESSAGE,
                            null,     // font
                            options,  //the titles of buttons
                            null); //default button title
                } else {
                    UI.put("OptionPane.background", new java.awt.Color(29, 29, 29));
                    UI.put("Panel.background", new java.awt.Color(29, 29, 29));
                    UI.put("OptionPane.messageForeground", font_dark);
                    input = JOptionPane.showOptionDialog(null,
                            "Would you like to disable dark mode?",
                            "Dark mode",
                            JOptionPane.YES_NO_OPTION,
                            JOptionPane.QUESTION_MESSAGE,
                            null,     //do not use a custom Icon
                            options,  //the titles of buttons
                            null); //default button title
                }
                if (input == 0) {
                    if (!dark) {
                        getContentPane().setBackground(new java.awt.Color(29, 29, 29));
                        textField.setBackground(co_dark);
                        generateButton.setBackground(co_dark);
                        copyToClipboardButton.setBackground(co_dark);
                        DMButton.setBackground(co_dark);

                        //Enable dark mode
                        generateButton.setOpaque(true);
                        copyToClipboardButton.setOpaque(true);
                        DMButton.setOpaque(true);

                        //Borders
                        Border kek = BorderFactory.createEtchedBorder(new java.awt.Color(69, 69, 69), new java.awt.Color(59, 59, 59));
                        textField.setBorder(kek);
                        generateButton.setBorder(kek);
                        copyToClipboardButton.setBorder(kek);
                        DMButton.setBorder(kek);

                        //Fonts
                        textField.setForeground(font_dark);
                        generateButton.setForeground(font_dark);
                        copyToClipboardButton.setForeground(font_dark);
                        DMButton.setForeground(font_dark);
                        textField.setCaretColor(font_dark);

                        dark = true;
                    } else {
                        //restore Background
                        getContentPane().setBackground(new java.awt.Color(255, 255, 255));
                        textField.setBackground(new java.awt.Color(255, 255, 255));
                        generateButton.setBackground(new JButton().getBackground());
                        copyToClipboardButton.setBackground(new JButton().getBackground());
                        DMButton.setBackground(new JButton().getBackground());

                        //restore Borders
                        textField.setBorder(new JTextField().getBorder());
                        generateButton.setBorder(new JButton().getBorder());
                        copyToClipboardButton.setBorder(new JButton().getBorder());
                        DMButton.setBorder(new JButton().getBorder());

                        //restore fonts
                        textField.setForeground(font_white);
                        generateButton.setForeground(font_white);
                        copyToClipboardButton.setForeground(font_white);
                        DMButton.setForeground(font_white);
                        textField.setCaretColor(font_white);

                        dark = false;
                    }

                }

            }
        });
        //Add all the methods & components to Jframe using add()
        add(textField);
        add(generateButton);
        add(copyToClipboardButton);
        add(DMButton);

        //Refresh the ui
        repaint();
    }

    //Basic function which checks the string's content is numeric or not.
    public static boolean isNumeric(String strNum) {
        if (strNum == null) {
            return false;
        }
        try {
            double d = Double.parseDouble(strNum);
        } catch (NumberFormatException nfe) {
            return false;
        }
        return true;
    }

    //This is a function which uses import java.security's SecureRandom library to create *TRUE* random password and not useless psuedoradom passwords using norm loops.
    // Usage is self explanatory.
    public static String genPass(int len) {
        final String chars = "AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpRrSsTtUuVvWwXxYyZz0123456789!@#$%^&*_=+-/€.?<>)";
        SecureRandom random = new SecureRandom(); // This class provides a cryptographically strong random number generator.
        StringBuilder sb = new StringBuilder(); // Build a changeable string.
        for (int i = 0; i < len; i++) {
            int randomIndex = random.nextInt(chars.length());
            sb.append(chars.charAt(randomIndex));
        }

        return sb.toString(); // Make sure to return string and not the whole object
    }

}