Java Calculator Pro

Simple Calculator in Java

import java.util.Scanner;

           public class Calculator

           {

           public static void main(String[] args)

           {

           Scanner input = new Scanner(System.in);

           Maths Maths = new Maths();

              double answer = 0;

    double inputA, inputB;

    char operator;

    boolean done = false;

                 while (done == false)

                   {

        System.out.print("Please enter your sum: ");

                   inputA = input.nextDouble();

        operator = input.next().charAt(0);

        inputB = input.nextDouble();       

        switch (operator)

        {

            case '+': answer = Maths.add(inputA, inputB);

                      break;

            case '-': answer = Maths.subtract(inputA, inputB);

                      break;

            case '*': answer = Maths.multiply(inputA, inputB);

                      break;

            case '/': answer = Maths.divide(inputA, inputB);

                      break;

            case '^': answer = Maths.power(inputA, inputB);

                      break;

        }

                        System.out.println(answer);            

    }      

             input.close();

              }

             }

public class Maths

{

    double add(double a, double b)

     {

        double answer = a+b;

        return answer;         

     }

              double subtract(double a, double b)

              {

        double answer = a-b;

        return answer;         

    }

    double multiply(double a, double b) 

    {

        double answer = a*b;

        return answer;         

    }

              double divide(double a, double b)

              {

        double answer = a/b;

        return answer;         

    }

              double power(double a, double b)

              {

        double answer =a;

                 for (int x=2; x<=b; x++)

                  {

            answer *= a;

        }

                   return answer;

    }

Java applet program for calculator

import java.awt.*;

import java.awt.event.*;

import java.applet.*; 

public class Cal extends Applet

implements ActionListener

{

   String msg=" ";

   int v1,v2,result;

   TextField t1;

   Button b[]=new Button[10];

   Button add,sub,mul,div,clear,mod,EQ;

   char OP;

   public void init()

   {

               Color k=new Color(120,89,90);

               setBackground(k);

               t1=new TextField(10);

               GridLayout gl=new GridLayout(4,5);

               setLayout(gl);

               for(int i=0;i<10 i="" span="">

               {

                   b[i]=new Button(""+i);

               }

               add=new Button("add");

               sub=new Button("sub");

               mul=new Button("mul");

               div=new Button("div");

               mod=new Button("mod");

               clear=new Button("clear");

               EQ=new Button("EQ");

               t1.addActionListener(this);

               add(t1);

               for(int i=0;i<10 i="" span="">

               {

                           add(b[i]);

               }

               add(add);

               add(sub);

               add(mul);

               add(div);

               add(mod);

               add(clear);

               add(EQ);

               for(int i=0;i<10 i="" span="">

               {

                           b[i].addActionListener(this);

               }

               add.addActionListener(this);

               sub.addActionListener(this);

               mul.addActionListener(this);

               div.addActionListener(this);

               mod.addActionListener(this);

               clear.addActionListener(this);

               EQ.addActionListener(this);

   }

   public void actionPerformed(ActionEvent ae)

   {

               String str=ae.getActionCommand();

               char ch=str.charAt(0);

               if ( Character.isDigit(ch))

               t1.setText(t1.getText()+str);

               else

               if(str.equals("add"))

               {

                           v1=Integer.parseInt(t1.getText());

                           OP='+';

                           t1.setText("");

               }

               else if(str.equals("sub"))

               {

                           v1=Integer.parseInt(t1.getText());

                           OP='-';

                           t1.setText("");

               }

               else if(str.equals("mul"))

               {

                           v1=Integer.parseInt(t1.getText());

                           OP='*';

                           t1.setText("");

               }

               else if(str.equals("div"))

               {

                           v1=Integer.parseInt(t1.getText());

                           OP='/';

                           t1.setText("");

                }

               else if(str.equals("mod"))

               {

                           v1=Integer.parseInt(t1.getText());

                           OP='%';

                           t1.setText("");

               }

               if(str.equals("EQ"))

               {

                           v2=Integer.parseInt(t1.getText());

                           if(OP=='+')

                                       result=v1+v2;

                           else if(OP=='-')

                                       result=v1-v2;

                           else if(OP=='*')

                                       result=v1*v2;

                           else if(OP=='/')

                                       result=v1/v2;

                           else if(OP=='%')

                                       result=v1%v2;

                           t1.setText(""+result);

               }          

               if(str.equals("clear"))

               {

                           t1.setText("");

               }

   }

}