Scientific Calculator | Steve Robinson

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.lang.Math;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;

/**
*Calculator GUI Class
*@author Steve Robinson
*@version 1.0
*/

    public class CalculatorFrame extends JFrame {

        public CalculatorFrame()
        {
            setTitle("My Scientific Calculator");

            CalculatorPanel calcPanel=new CalculatorPanel();
            add(calcPanel);
            pack();
        }
    }

    class CalculatorPanel extends JPanel
    {
        private JTextField display1;
        private JTextField display2;
        private JPanel buttonPanel;
        private JPanel displayPanel;

        public CalculatorPanel()
        {
            ActionListener listener=new CalculatorListener();
            ActionListener displayListener=new DisplayListener();


            setLayout(new BorderLayout());

            //Display
            displayPanel=new JPanel();
            displayPanel.setLayout(new GridLayout(2,1));

            display1=new JTextField("");
            displayPanel.add(display1);
            display2=new JTextField("");
            displayPanel.add(display2);

            add(displayPanel,BorderLayout.NORTH);

            //Create a panel for Buttons
            buttonPanel=new JPanel();
            buttonPanel.setLayout(new GridLayout(8,4));

            //Button Creation
            JButton e=new JButton("e");
            e.addActionListener(listener);
            buttonPanel.add(e);

            JButton DEL=new JButton("DEL");
            DEL.addActionListener(displayListener);
            buttonPanel.add(DEL);

            JButton AC=new JButton("AC");
            AC.addActionListener(displayListener);
            buttonPanel.add(AC);

            JButton OFF=new JButton("OFF");
            OFF.addActionListener(displayListener);
            buttonPanel.add(OFF);

            JButton log=new JButton("log");
            log.addActionListener(listener);
            buttonPanel.add(log);

            JButton sin=new JButton("sin");
            sin.addActionListener(listener);
            buttonPanel.add(sin);

            JButton tan=new JButton("tan");
            tan.addActionListener(listener);
            buttonPanel.add(tan);

            JButton cos=new JButton("cos");
            cos.addActionListener(listener);
            buttonPanel.add(cos);

            JButton mod=new JButton("%");
            mod.addActionListener(listener);
            buttonPanel.add(mod);

            JButton x_2=new JButton("x^2");
            x_2.addActionListener(listener);
            buttonPanel.add(x_2);

            JButton x_3=new JButton("x^3");
            x_3.addActionListener(listener);
            buttonPanel.add(x_3);

            JButton sqrt=new JButton("sqrt");
            sqrt.addActionListener(listener);
            buttonPanel.add(sqrt);

            JButton reciprocal=new JButton("1/x");
            reciprocal.addActionListener(listener);
            buttonPanel.add(reciprocal);

            JButton lParan=new JButton("(");
            lParan.addActionListener(listener);
            buttonPanel.add(lParan);

            JButton rParan=new JButton(")");
            rParan.addActionListener(listener);
            buttonPanel.add(rParan);

            JButton ANS=new JButton("ANS");
            ANS.addActionListener(listener);
            buttonPanel.add(ANS);

            JButton seven=new JButton("7");
            seven.addActionListener(listener);
            buttonPanel.add(seven);

            JButton eight=new JButton("8");
            eight.addActionListener(listener);
            buttonPanel.add(eight);

            JButton nine=new JButton("9");
            nine.addActionListener(listener);
            buttonPanel.add(nine);

            JButton add=new JButton("+");
            add.addActionListener(listener);
            buttonPanel.add(add);

            JButton four=new JButton("4");
            four.addActionListener(listener);
            buttonPanel.add(four);

            JButton five=new JButton("5");
            five.addActionListener(listener);
            buttonPanel.add(five);

            JButton six=new JButton("6");
            six.addActionListener(listener);
            buttonPanel.add(six);

            JButton minus=new JButton("-");
            minus.addActionListener(listener);
            buttonPanel.add(minus);

            JButton one=new JButton("1");
            one.addActionListener(listener);
            buttonPanel.add(one);

            JButton two=new JButton("2");
            two.addActionListener(listener);
            buttonPanel.add(two);

            JButton three=new JButton("3");
            three.addActionListener(listener);
            buttonPanel.add(three);

            JButton divide=new JButton("/");
            divide.addActionListener(listener);
            buttonPanel.add(divide);

            JButton zero=new JButton("0");
            zero.addActionListener(listener);
            buttonPanel.add(zero);

            JButton decimal=new JButton(".");
            decimal.addActionListener(listener);
            buttonPanel.add(decimal);

            JButton equal=new JButton("=");
            equal.addActionListener(listener);
            buttonPanel.add(equal);

            JButton multiply=new JButton("*");
            multiply.addActionListener(listener);
            buttonPanel.add(multiply);

            add(buttonPanel,BorderLayout.CENTER);


        }

        //Script Engine Creation
        ScriptEngineManager manager=new ScriptEngineManager();
        ScriptEngine engine=manager.getEngineByName("JavaScript");

        //ActionListener for Display Functions
        private class DisplayListener implements ActionListener
        {
            public void actionPerformed(ActionEvent event)
            {
                String command=event.getActionCommand();

                if(command.equals("AC"))
                {
                    display1.setText("");
                    display2.setText("");
                }
                else if(command.equals("OFF"))
                {
                    System.exit(0);
                }
                else if(command.equals("DEL"))
                {
                    display1.setText(display1.getText().substring(0, display1.getText().length()-1));
                }
            }
        }

        //ActionListener for Calculator Functions
        private class CalculatorListener implements ActionListener
        {
            public void actionPerformed (ActionEvent event)
            {
                String command=event.getActionCommand();
                //double oprOneVal = 0;
                //double oprTwoVal=0;
                //String operator="";
                //boolean operand1=true;
                //boolean operand2=false;

                try{
                    if(command.equals("log"))
                    {
                        double input=evaluateExpression(display1.getText());

                            display2.setText(Double.toString(Math.log(input)));

                    }

                    else if(command.equals("sin"))
                    {
                        double input=evaluateExpression(display1.getText());
                        display2.setText(Double.toString(Math.sin(input)));
                    }


                    else if(command.equals("tan"))
                    {
                        double input=evaluateExpression(display1.getText());
                        display2.setText(Double.toString(Math.tan(input)));
                    }


                    else if(command.equals("cos"))
                    {
                        double input=evaluateExpression(display1.getText());
                        display2.setText(Double.toString(Math.cos(input)));
                    }

                    else if(command.equals("e"))
                    {
                        double input=evaluateExpression(display1.getText());
                        display2.setText(Double.toString(Math.exp(input)));
                    }


                    else if(command.equals("x^2"))
                    {
                        double input=evaluateExpression(display1.getText());
                        display2.setText(Double.toString(input*input));
                    }

                    else if(command.equals("x^3"))
                    {
                        double input=evaluateExpression(display1.getText());
                        display2.setText(Double.toString(input*input*input));
                    }

                    else if(command.equals("sqrt"))
                    {
                        double input=evaluateExpression(display1.getText());
                        display2.setText(Double.toString(Math.sqrt(input)));
                    }
                    else if(command.equals("="))
                    {
                        String input=display1.getText();
                        System.out.println(input);
                        display2.setText(Double.toString(evaluateExpression(input)));
                    }
                    else if(command.equals("ANS"))
                    {
                        String answer=display1.getText();
                        char last=answer.charAt(answer.length()-1);
                        if(Character.isDigit(last)||last==')'||last=='(')
                            display1.setText(display2.getText());
                        else
                            display1.setText(display1.getText()+display2.getText());
                    }
                    else if(command.equals("1/x"))
                    {
                        double input=evaluateExpression(display1.getText());
                        display2.setText(Double.toString(1/input));
                    }
                    else
                    {
                        display1.setText(display1.getText()+command);
                    }
                }
                catch (Exception ex)
                {
                    ex.printStackTrace();
                }


            }

            //Expression Evaluator
            Double evaluateExpression (String expression) throws Exception
            {
                System.out.println(expression);
                return (Double) engine.eval(expression);
            }
        }



}

============================================================================================

//Calculator.java
//MainClass

import java.awt.EventQueue;

import javax.swing.JFrame;


public class Calculator {

    public static void main(String arg[])
    {
        EventQueue.invokeLater(new Runnable()
        {
            public void run()
            {
                CalculatorFrame calculator=new CalculatorFrame();
                calculator.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                calculator.setVisible(true);
            }
        });
    }

}