import java.applet.*; import java.awt.*; import java.awt.event.*; class Calc extends Applet implements ActionListener { String cmd[] = {"+", "-", "*", "/", "=", "C"}; int pv = 0; String op = ""; Button b[] = new Button[16]; TextField t1 = new TextField(10); public void init() { setLayout(new BorderLayout()); add(t1, "North"); t1.setText("0"); Panel p = new Panel(); p.setLayout(new GridLayout(4, 4)); for (int i = 0; i < 16; i++) { if (i < 10) b[i] = new Button(String.valueOf(i)); else b[i] = new Button(cmd[i % 10]); b[i].setFont(new Font("Arial", Font.BOLD, 25)); p.add(b[i]); add(p, "Center"); b[i].addActionListener(this); } } public void actionPerformed(ActionEvent ae) { int res = 0; String cap = ae.getActionCommand(); int cv = Integer.parseInt(t1.getText()); if (cap.equals("C")) { t1.setText("0"); pv = 0; cv = 0; res = 0; op = ""; } else if (cap.equals("=")) { res = 0; if (op == "+") res = pv + cv; else if (op == "-") res = pv - cv; else if (op == "*") res = pv * cv; else if (op == "/") res = pv / cv; t1.setText(String.valueOf(res)); } else if (cap.equals("+") || cap.equals("-") || cap.equals("*") || cap.equals("/")) { pv = cv; op = cap; t1.setText("0"); } else { int v = cv * 10 + Integer.parseInt(cap); t1.setText(String.valueOf(v)); } } } /* */ My lesson highlights! Check it out on your phone in Programming Hub: https://goo.gl/D2iETN