Java Calculator

Калькулятор с двумя регистрами памяти (апплет)

В этом апплете использованы следующие классы:
Calc - расширяет класс Applet
docalc - определяет ActionListener, его методы :

public double parseDouble(String s) - перевод строки в число
private void compute() - вычисление действия над операндами
private void foperation(char character) - устновка типа задействованой операции
private void addChar(String s) - добавление нажатой цифры к строке ввода
public void actionPerformed(ActionEvent e) - обработка нажатий на клавиши

класс Calculator расширяет класс Panel, его метод :

private void setup(docalc dc) - установка внешнего вида панели калькулятора

Исходный текст апплета калькулятор:

import java.awt.*;
import java.awt.event.*;
import java.lang.*;
import java.applet.*;
//=======================================================================
class Calc extends Applet
{
 public void init()
  {   	
   setLayout(new BorderLayout());
   Calculator Cr = new Calculator();
   add("Center",Cr);
  }
}
//=======================================================================
class docalc implements ActionListener
{
 private static double op1 = 0, op2, op3;
 private static double mem1 = 0,mem2 = 0;
 private static double inputvalue = 0;
 private static char f;
 private static int f1,f2;
 private static String lastkey = "clear";

private static String str_num = "";
 private static double num = 0.0;
//-----------------------------------------------------------------------
public double parseDouble(String s)
 {
	double g=0.0;
	long f=0;
	int i=0;
	int j=0;
	String s1="";
	String s2="";
	j=s.indexOf('.');
	 if (j>=0)
	 {
	  System.out.println(j);
 	  s1=s.substring(j+1);
	  System.out.println(s1);
	  f=Long.parseLong(s1,10);
	  System.out.println(f);
	  s2=s.substring(0,j);
	  System.out.println(s2);
	  i=s1.length();
	  System.out.println(i);
	  g=Math.pow(10,i);
	  System.out.println(g);
	  g=f/g;
	  System.out.println(g);
	  f=Long.parseLong(s2,10);
	  System.out.println(f);
	  return (double)(g+f);
	 }
	 return g=(double)(Long.parseLong(s));
}
//-----------------------------------------------------------------------------------
private void compute()
{
	if(f == '/')
	   inputvalue = op1/op2;
	if(f == '*')
	   inputvalue = op1*op2;
	if(f == '-')
	   inputvalue = op1-op2;
	if(f == '+')
	   inputvalue = op1+op2;
        String s = Double.toString(inputvalue);
	str_num = s;
        Calculator.disp.setText(s);
}
//-----------------------------------------------------------------------------------
private void  foperation(char character)
{
	if(lastkey == "operation")
	 { f = character;
	   return;
	 }
	f2 = 1;
	if(f1 == 0)
	 {
	   op1 = inputvalue;
	   f1 = 1;
	 }
	else
	 {
	   op2 = inputvalue;
	   compute();
	   op1 = inputvalue;
	 }
	lastkey = "operation";
	f = character;
}
//-----------------------------------------------------------------------------------
private void addChar(String s)
{
      if(str_num == "0" || f2 == 1)
	{
         str_num = s;
	 f2 = 0;
	}
	else
 	{
         str_num += s;
	}
      lastkey = "number";
      Calculator.disp.setText(str_num);
}
//-----------------------------------------------------------------------------------
public void actionPerformed(ActionEvent e)
{
  String str = e.getActionCommand();
  char w;
  if ((Character.isDigit(str.charAt(0)))||(str.charAt(0)=='.'))
   {
    if ((str.charAt(0)=='.')&&(str_num.indexOf('.')==-1))
     addChar(".");
    else
     if(Character.isDigit(str.charAt(0)))
      addChar(str);
    return;
   }
  if (str_num.length() >= 1)
   {
      try
       {
	 num=parseDouble(str_num);
       }
      catch(Exception q)
       {
	System.out.println("Found Exception!"+q);
       }
      inputvalue = num;

w = str.charAt(0);
      if((w == '+')||(w == '-')||(w == '*')||(w == '/'))
       {
        foperation(w);
	return;
       }	
   }
   if (str.equals("="))
    {
     if(lastkey == "enter")
       { op2 = op3;          	
     	 op1 = inputvalue;    	
       }                   	
  	else                	
       { op2 = inputvalue;     	
  	 op3 = op2;        	
       };                  	
     compute();	  	
     f1 = 0;   f2 = 1;               	
     lastkey="enter";
     return;
    }
   if (str.equals("C"))
    {	f = 'x';
	op1 = 0;
	f1 = 0;
	f2 = 1;
	inputvalue = 0;
	str_num = "";
        Calculator.disp.setText("0.0");
	lastkey = "clear";
        return;
   }
   if (str.equals("M1+"))
    {      f2 = 1;
           mem1+=num;
           String s = Double.toString(mem1);
           Calculator.disp1.setText(s);
	   lastkey = "memadd";
	   return;
    }
   if (str.equals("M2+"))
    {      f2 = 1;
           mem2+=num;
           String s = Double.toString(mem2);
           Calculator.disp2.setText(s);
	   lastkey = "memadd";
	   return;
    }
   if (str.equals("MC1"))
    {      mem1 = 0;
           String s = Double.toString(mem1);
           Calculator.disp1.setText(s);
	   return;
    }
   if (str.equals("MC2"))
    {      mem2 = 0;
           String s = Double.toString(mem2);
           Calculator.disp2.setText(s);
	   return;
    }
   if (str.equals("MR1"))
    {      f2 = 1;
           String s = Double.toString(mem1);
	   str_num = s;
           Calculator.disp.setText(s);
	   lastkey = "memread";
	   return;
    }
   if (str.equals("MR2"))
    {      f2 = 1;
           String s = Double.toString(mem2);
	   str_num = s;
           Calculator.disp.setText(s);
	   lastkey = "memread";
	   return;
    }
   if (str.equals("<-"))
    {   int i;
	if(str_num == "0")
	 return;
    	if(str_num.length() == 1)
     	  str_num = "0";
	  else
    	 if(str_num.length() == 2 && str_num.substring(0,1) == "-" )
     	  str_num = "0";
	  else
	 if(str_num.charAt(str_num.length()-2)=='.')
	  str_num = str_num.substring(0,str_num.length()-2);
	   else
	  str_num = str_num.substring(0,str_num.length()-1);

Calculator.disp.setText(str_num);
	return;
    }
   if (str.equals("(-)"))
    {
	if(str_num == "0")
	 return;
	if(str_num.substring(0,1) == "-")
	  str_num = str_num.substring(1,str_num.length());
	 else
	  str_num = "-" + str_num;
	
        Calculator.disp.setText(str_num);
    }
}

}
//=======================================================================
class Calculator extends Panel
{ docalc l;
 // constructor
  Calculator()
   {
    l=new docalc();
    setup(l);
   }
// public static Texdispield disp = null;

public static TextField disp = null;
 public static TextField disp1 = null;
 public static TextField disp2 = null;
//-----------------------------------------------------------------------------------
private void setup(docalc dc)
{
 disp = new TextField(30);
 disp.setEditable(false);
 disp.setBackground(Color.green);
 disp.setForeground(Color.black);
 disp.setText("0.0");

disp1 = new TextField(30);
 disp1.setEditable(false);
 disp1.setBackground(Color.green);
 disp1.setForeground(Color.black);

disp2 = new TextField(30);
 disp2.setEditable(false);
 disp2.setBackground(Color.green);
 disp2.setForeground(Color.black);

GridBagConstraints gbc = new GridBagConstraints();

setLayout(new GridBagLayout());

gbc.insets = new Insets(2, 2, 2, 2);

gbc.gridx = 0;
 gbc.gridy = 0;
 gbc.gridwidth = 10;
 gbc.anchor = GridBagConstraints.WEST;

Panel centerPanel=new Panel();
 Panel buttonPanel=new Panel();

buttonPanel.setLayout(new GridLayout(6,6,5,6));
 buttonPanel.setBackground(Color.white);
 centerPanel.setBackground(Color.white);
//--------------------------------------------------------------
    docalc buttonListener = new docalc();

Button b1 = new Button("MR1");
    b1.addActionListener(buttonListener);
    buttonPanel.add(b1);

Button b18 = new Button("7");
    b18.addActionListener(buttonListener);
    buttonPanel.add(b18);

Button b19 = new Button("8");
    b19.addActionListener(buttonListener);
    buttonPanel.add(b19);

Button b20 = new Button("9");
    b20.addActionListener(buttonListener);
    buttonPanel.add(b20);

Button b16 = new Button("/");
    b16.addActionListener(buttonListener);
    buttonPanel.add(b16);
	
    Button b6 = new Button("MR2");
    b6.addActionListener(buttonListener);
    buttonPanel.add(b6);
	
	Button b13 = new Button("4");
    b13.addActionListener(buttonListener);
    buttonPanel.add(b13);

Button b14 = new Button("5");
    b14.addActionListener(buttonListener);
    buttonPanel.add(b14);

Button b15 = new Button("6");
    b15.addActionListener(buttonListener);
    buttonPanel.add(b15);

Button b17 = new Button("*");
    b17.addActionListener(buttonListener);
    buttonPanel.add(b17);

Button b7 = new Button("M1+");
    b7.addActionListener(buttonListener);
    buttonPanel.add(b7);

Button b8 = new Button("1");
    b8.addActionListener(buttonListener);
    buttonPanel.add(b8);

Button b9 = new Button("2");
    b9.addActionListener(buttonListener);
    buttonPanel.add(b9);

Button b10 = new Button("3");
    b10.addActionListener(buttonListener);
    buttonPanel.add(b10);

Button b11 = new Button("-");
    b11.addActionListener(buttonListener);
    buttonPanel.add(b11);

Button b5 = new Button("M2+");
    b5.addActionListener(buttonListener);
    buttonPanel.add(b5);

Button b25 = new Button("0");
    b25.addActionListener(buttonListener);
    buttonPanel.add(b25);
	
    Button b27 = new Button(".");
    b27.addActionListener(buttonListener);
    buttonPanel.add(b27);
	
	Button b30 = new Button("(-)");
    b30.addActionListener(buttonListener);
    buttonPanel.add(b30);

Button b12 = new Button("+");
    b12.addActionListener(buttonListener);
    buttonPanel.add(b12);

Button b21 = new Button("MC1");
    b21.addActionListener(buttonListener);
    buttonPanel.add(b21);

Button b22 = new Button("MC2");
    b22.addActionListener(buttonListener);
    buttonPanel.add(b22);

Button b23 = new Button("C");
    b23.addActionListener(buttonListener);
    buttonPanel.add(b23);

Button b24 = new Button("<-");
    b24.addActionListener(buttonListener);
    buttonPanel.add(b24);

Button b26 = new Button("=");
    b26.addActionListener(buttonListener);
    buttonPanel.add(b26);

centerPanel.add(disp);
    centerPanel.add(disp1);
    centerPanel.add(disp2);

setLayout(new BorderLayout());
    add("Center",centerPanel);
    add("South",buttonPanel);

}
}