I've made a calculator program in java and i need to rewrite the code to use as an applet. Can someone please rewrite this code and explain the changes made in order to make the below code run as an applet?

My Code:

package calculator; import java.awt.event.*; import javax.swing.*; import java.awt.*; public class BasicCalculator1 implements ActionListener{//attributes protected JFrame calWin; protected JPanel keyPad; protected JPanel panel; protected JTextField show; protected JButton b0, b1, b2, b3, b4, b5, b6, b7, b8, b9; protected JButton add, sub, mul, div, com, clr; protected double o1, o2; protected char op; //constructors public BasicCalculator1(){ clean();} //methods public void clean(){ o1 = 0; o2 = 0; op = ' ';} public void createUserInterface() { calWin = new JFrame("Calculator"); keyPad = new JPanel(); keyPad.setLayout(new GridLayout(4,4,4,4)); show = new JTextField(15); show.setEditable(false); show.setBackground(Color.YELLOW); show.setFont(new Font("SERIF", Font.PLAIN, 32)); b0 = new JButton("0"); b0.setBackground(Color.CYAN); b0.setFont(new Font("SERIF", Font.PLAIN, 32)); b1 = new JButton("1"); b1.setBackground(Color.CYAN); b1.setFont(new Font("SERIF", Font.PLAIN, 32)); b2 = new JButton("2"); b2.setBackground(Color.CYAN); b2.setFont(new Font("SERIF", Font.PLAIN, 32)); b3 = new JButton("3"); b3.setBackground(Color.CYAN); b3.setFont(new Font("SERIF", Font.PLAIN, 32)); b4 = new JButton("4"); b4.setBackground(Color.CYAN); b4.setFont(new Font("SERIF", Font.PLAIN, 32)); b5 = new JButton("5"); b5.setBackground(Color.CYAN); b5.setFont(new Font("SERIF", Font.PLAIN, 32)); b6 = new JButton("6"); b6.setBackground(Color.CYAN); b6.setFont(new Font("SERIF", Font.PLAIN, 32)); b7 = new JButton("7"); b7.setBackground(Color.CYAN); b7.setFont(new Font("SERIF", Font.PLAIN, 32)); b8 = new JButton("8"); b8.setBackground(Color.CYAN); b8.setFont(new Font("SERIF", Font.PLAIN, 32)); b9 = new JButton("9"); b9.setBackground(Color.CYAN); b9.setFont(new Font("SERIF", Font.PLAIN, 32)); add = new JButton("+"); add.setBackground(Color.RED); add.setFont(new Font("SERIF", Font.PLAIN, 32)); sub = new JButton("-"); sub.setBackground(Color.RED); sub.setFont(new Font("SERIF", Font.PLAIN, 32)); mul = new JButton("*"); mul.setBackground(Color.RED); mul.setFont(new Font("SERIF", Font.PLAIN, 32)); div = new JButton("/"); div.setBackground(Color.RED); div.setFont(new Font("SERIF", Font.PLAIN, 32)); com = new JButton("="); com.setBackground(Color.RED); com.setFont(new Font("SERIF", Font.PLAIN, 32)); clr = new JButton("Clear"); clr.setBackground(Color.RED); clr.setFont(new Font("SERIF", Font.PLAIN, 20)); calWin.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent windowEvent){ System.exit(0);}}); panel = new JPanel(); panel.setSize(300,300); BorderLayout layout = new BorderLayout(); layout.setHgap(10); layout.setVgap(4); panel.setLayout(layout); keyPad.add(b0); keyPad.add(b1); keyPad.add(b2); keyPad.add(b3); keyPad.add(b4); keyPad.add(b5); keyPad.add(b6); keyPad.add(b7); keyPad.add(b8); keyPad.add(b9); keyPad.add(add); keyPad.add(sub); keyPad.add(mul); keyPad.add(div); keyPad.add(com); keyPad.add(clr); panel.add(show,BorderLayout.NORTH); panel.add(keyPad,BorderLayout.CENTER); calWin.getContentPane().add(panel); calWin.setBackground(Color.lightGray); calWin.setSize(400, 400); calWin.setVisible(true); b0.addActionListener(this); b1.addActionListener(this); b2.addActionListener(this); b3.addActionListener(this); b4.addActionListener(this); b5.addActionListener(this); b6.addActionListener(this); b7.addActionListener(this); b8.addActionListener(this); b9.addActionListener(this); add.addActionListener(this); sub.addActionListener(this); mul.addActionListener(this); div.addActionListener(this); com.addActionListener(this); clr.addActionListener(this);} public void actionPerformed(ActionEvent e){ if(e.getSource() == b0){ show.setText(show.getText() + "0");} if(e.getSource() == b1){ show.setText(show.getText() + "1");} if(e.getSource() == b2){ show.setText(show.getText() + "2");} if(e.getSource() == b3){ show.setText(show.getText() + "3");} if(e.getSource() == b4){ show.setText(show.getText() + "4");} if(e.getSource() == b5){ show.setText(show.getText() + "5");} if(e.getSource() == b6){ show.setText(show.getText() + "6");} if(e.getSource() == b7){ show.setText(show.getText() + "7");} if(e.getSource() == b8){ show.setText(show.getText() + "8");} if(e.getSource() == b9){ show.setText(show.getText() + "9");} if(e.getSource() == add){ o1 = Double.parseDouble(show.getText()); op = '+'; show.setText("");} if(e.getSource() == sub){ if(show.getText().trim().equals("")){ show.setText("-");} else{ o1 = Double.parseDouble(show.getText()); op = '-'; show.setText(""); } } if(e.getSource() == mul){ o1 = Double.parseDouble(show.getText()); op = '*'; show.setText("");} if(e.getSource() == div){ o1 = Double.parseDouble(show.getText()); op = '/'; show.setText("");} if(e.getSource() == com){ o2 = Double.parseDouble(show.getText()); calculate();} if(e.getSource() == clr){ show.setText(""); clean(); } } public void calculate(){ switch(op){ case '+': show.setText(new Double(o1 + o2).toString());break; case '-': show.setText(new Double(o1 - o2).toString());break; case '*': show.setText(new Double(o1 * o2).toString());break; case '/': show.setText(new Double(o1 / o2).toString());break; } } public static void main(String[] args){ try {UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName());} catch (Exception e) { e.printStackTrace(); } BasicCalculator1 c; c = new BasicCalculator1(); c.createUserInterface(); } }