design an awt calculator code example

Example: design an awt calculator

import java.awt.*;import java.awt.event.*; class MyCalculator extends Frame implements ActionListener {  TextField tfInput; Panel panel;  String btnString[] = {"7", "8", "9", "+",                 "4", "5", "6", "-",                 "1", "2", "3", "*",                 "C", "0", "=", "/"};Button btn[] = new Button[16];    int num1 = 0, num2 = 0, result = 0; char op;  public MyCalculator() {   Font f = new Font("Cambria", Font.BOLD, 18);    tfInput = new TextField(10);  tfInput.setFont(f);    panel = new Panel();    add(tfInput, "North");  add(panel, "Center");    panel.setLayout(new GridLayout(4,4));    for(int i=0; i < 16; i++) {      btn[i] = new Button(btnString[i]);   btn[i].setFont(f);   btn[i].addActionListener(this);   panel.add(btn[i]);  }    addWindowListener(new WindowAdapter(){      public void windowClosing(WindowEvent we) {    System.exit(0);   }  }); }  public void actionPerformed(ActionEvent ae) {    String str = ae.getActionCommand();    if(str.equals("+")) {      op = '+';   num1 = Integer.parseInt(tfInput.getText());   tfInput.setText("");  }  else if(str.equals("-")) {   op = '-';   num1 = Integer.parseInt(tfInput.getText());   tfInput.setText("");  }  else if(str.equals("*")) {   op = '*';   num1 = Integer.parseInt(tfInput.getText());   tfInput.setText("");  }  else if(str.equals("/")) {   op = '/';   num1 = Integer.parseInt(tfInput.getText());   tfInput.setText("");  }  else if(str.equals("=")) {      num2 = Integer.parseInt(tfInput.getText());      switch(op) {        case '+' : result = num1 + num2;     break;    case '-' : result = num1 - num2;     break;    case '*' : result = num1 * num2;     break;    case '/' : result = num1 / num2;     break;   }   tfInput.setText(result + "");   result = 0;  }  else if(str.equals("C")) {      tfInput.setText("");   num1 = num2 = result = 0;  }  else {   tfInput.setText(tfInput.getText() + str);  } }  public static void main(String args[]) {    MyCalculator m = new MyCalculator();  m.setTitle("My Calculator");  m.setSize(250,300);  m.setVisible(true); }}