calculator_app.java

a calculator applet developed in java to perform mathematical calculations

	if(str.compareTo("0")==0||op!="")
		str=e.getActionCommand();
		else str=str+e.getActionCommand();
			str3=str;
		textf.setText(str);
		showStatus(e.getActionCommand());
	}
	else if ((e.getSource()==button[37])|| (e.getSource()==button[35])||(e.getSource()==button[33])||(e.getSource()==button[31])||(e.getSource()==button[25]))
	{ // "+" "+" "-" "*" "/" Buttons 
		cond5=true;
		String tempStr="";
		op=e.getActionCommand();
		str1=str;
		str3=str;
		tempStr = str;
		str="0";
		textf.setText(tempStr);
	}
	else if ((e.getSource()==button[18])) // "=" Button
		{ 	calculate();
			//f.CreateFile();	
			}
		else if (e.getSource()==button[5]) //  "BackSpace" Button 
		{
			if(str.length() != 0)
			{
				str=str.substring(0,str.length()-1);
				textf.setText(str);
			}
			else
			JOptionPane.showMessageDialog(null, "Do not use backspace now.");
		}
		else if (e.getSource()==button[3]) // "C" Button 
		{
			op="";
			str=str3;
			textf.setText(str);
		}
		else if (e.getSource()==button[4]) //"CE" Button 
		{
			textf.setText("0");
			cond5=true;
			str="0";
			str1="";
			str2="";
		}
		else if (e.getSource()==button[27]) //  "1/X" button  
		{
			pressed=true;
			float g=0,p=0;
			p=Float.valueOf(str).floatValue();
			if(p==0)
			{
				str="0";
				textf.setText("Infinite");
			}
			else
			{
				g=(1/p);
				str=""+g;
				str3=str;
				textf.setText(str);
				f.CreateFile();
				f.addTofile("1/"+p+"="+str);
			}
		}
		else if (e.getSource()==button[28]) // "+/-" Button
		{
            if (!(str.compareTo("0")==0))
            {
                if(str.charAt(0)=='-')
					str=str.substring(1,str.length());
            	else
      		      	str="-"+str;
			textf.setText (str);
            }
        }
	else if(e.getSource()==button[34]) // "Me" button 
	{
		pressed=true;
		memoryTagLabel.setText("M");
		mem = Double.valueOf(str).doubleValue();
		if(mem==0)
			memoryTagLabel.setText(" ");
		showStatus("Memory="+mem);
	}
	else if(e.getSource()==button[36]) //"M+" Button
	{
		pressed=true;
		memoryTagLabel.setText("M");
		mem=mem+(Double.valueOf(str).doubleValue());
		if(mem==0)
			memoryTagLabel.setText(" ");
		showStatus("Memory="+mem);
	}
	else if(e.getSource()==button[38]) //"M-" Button
	{
		pressed=true;
		memoryTagLabel.setText("M");
		mem=mem-(Double.valueOf(str).doubleValue());
		if(mem==0)
			memoryTagLabel.setText(" ");
		showStatus("Memory="+mem);

	}
	else if(e.getSource()==button[39]) //"MR" Button
	{
		str=""+mem;
		str3=str;
		textf.setText(str3);
	}
	
	else if(e.getSource()==button[23])
	{
			pressed=true;
	   		double y=0;
			double x=Double.valueOf(str).doubleValue();
			y=Math_class.sqr_func(x);
			textf.setText(""+y);
			str=""+y;
			str3=str;
			f.CreateFile();
			f.addTofile("sqr("+x+")="+str);
	}
	else if(e.getSource()==button[24])
    {
	   	pressed=true;
		int x=Integer.valueOf (str).intValue();
		if(x>39)
			textf.setText("Infinite");
		else
		{
			str=""+Math_class.fact_func(x);
			textf.setText(""+str);
			str3=str;
			f.CreateFile();
			f.addTofile(""+x+"!="+str);
	    }

	}
	else if(e.getSource()==button[2]) //"Shift" Button
	{
		if(!cond3)
		{
			button[20].setLabel("arcSin");
			button[21].setLabel("arcCos");
			cond3=true;
		}
		else
		{
			cond3=false;
			button[20].setLabel ("Sin");
			button[21].setLabel ("Cos");
		}
	}
	else if(e.getSource()==button[40]) //" R" Button
	{
		textf.setText("0");
		mem=0;
		memoryTagLabel.setText("");
	}
	else if(e.getSource()==button[26])
	{
		pressed=true;
		float p,r;
		p=Float.valueOf(str).floatValue();
		r=p/100;
		str=""+r;
		str3=str;
		textf.setText(str);
		f.CreateFile();
		f.addTofile(""+p+"%="+str);
	}
	else if(e.getSource()==button[22])
	{
		pressed=true;
		double l=0;
		m=Double.valueOf(str).doubleValue();
		l=Math.sqrt(m);
		str=""+l;
		str3=str;
		textf.setText(str);
		f.CreateFile();
		f.addTofile("sqrt("+m+") ="+str);
	}
	else if (e.getSource()==button[19])
	{
		pressed=true;
	  	textf.setText(str3);
		str=str3;
		showStatus(str3);
	}
	else if (e.getSource()==button[17])
	{
		pressed=true;
		textf.setText(""+3.1415926);
		str=""+3.1415926;
	}
	
}//Method ends action performed.

public void calculate()
{
	double l=0;
	int o=0;
	String opp="";
	str2=str;
	str="0";
	m=Double.valueOf(str1).doubleValue();
	n=Double.valueOf(str2).doubleValue();
	opp=op;
	if (op.compareTo("+")==0)
	{	
			l=m+n;
			op="";
	}
    else if (op.compareTo("-")==0)
    {
		l=m-n;
		op="";
	}
    else if (op.compareTo("*")==0)
    {
       	l=m*n;
		op="";
    }
    else if (op.compareTo("/")==0)
    {
		l=m/n;
		op="";
	}
    else if (op.compareTo("")==0)
    {
		l=Double.valueOf(str2).doubleValue();
    }
    else if (op.compareTo("Pow")==0)
    {
		o=Integer.valueOf(str2).intValue();
		l=Math_class.pow_func(m,o);
		op="";
    }
    cond5=true;
    pressed=true;//pressed=true specify the
//End user has pressed a symbol key such as, +, -, /.
    str=""+l;
    textf.setText(str);
    f.CreateFile();
    f.addTofile(str1+opp+str2+"="+l);
}//End of method declaration "calculate".



class File_class
{
	DataOutputStream Of;
	
public void WriteFileOnTextArea()// Method to write in the file.
{
    String str;
 	char st;
	str="";
	try
	{
		DataInputStream If=new DataInputStream(new FileInputStream("FileOut.txt"));
	    while(If.readLine()!=null)
        {
	       	if ((st=If.readChar())!='E')
        	{
               	str=st+str;
        	}
        	if (st=='E')
        	{
        		textarea1.setText("");
	    		textarea1.append(str);
        		textarea1.append("\n");
      	   		str="";
        	}
      	}//Ed while.
      	If.close();
	}//End try.
 	catch(FileNotFoundException e){}  	 //Catches the error if the file is not found.
    catch(IOException e) {}
}// End of method WriteFileOnTextArea().

public void CreateFile()
{
	try
 	{
		Of = new DataOutputStream(new  FileOutputStream("FileOut.txt"));
  		Of.writeChars("Begin\n");
    }
    catch(IOException e) 
    {
		System.err.println("File not opened properly\n"+e.toString());
	    System.exit(1);
    }
}




public void endStore()
{
	try
 	{
		Of.close();
    }
    catch(IOException e) 
    {
		System.err.println("File not closed properly\n"+e.toString());
	    System.exit(1);
    }
}


public void addTofile(String str)
{
	try
	{
		for(int i=str.length()-1;i>=0;i--)
		{
			Of.writeChar(str.charAt(i));
			Of.writeChars("\n");
		}
		Of.writeChar('E');
		Of.writeChars("\n");
	}
	catch (IOException io){}
}

public void delFile()
{
	CreateFile();
	try
	{
		Of.close();
	}
	catch (IOException io){}
}


} //End of File_class

}  // End of class Calculate_class




class Math_class  // MATH CLASS
{

	public static double sin_func(double x)
	{
		if (x<=0.0005)
			x=x+((x*x*x)/6);
		else
		 	x=2*sin_func(x/2)*cos_func(x/2);
		return x;
	}

	public static double cos_func (double x)
	{
		if (x<=0.0005)
			x=1-((x*x*x)/2);
		else
			x=(cos_func(x/2)*cos_func(x/2))-(sin_func(x/2)*sin_func(x/2));
		return x;
	}// End of cos_func() method.

	public static double convert_rad_deg (double x)
	{
		//converting from radian to degree 	
		double y;
		y=(180*x)/Math.PI;
		return y;
	}

	public static double convert_deg_rad (double x)
	{
		//Converting from degree to radian. 
		double y;
		y=(Math.PI*x)/180;
		return y;
	}

	public static double pow_func(double x,int y)
	{
		double s;
		s=1;
		for(int i=1;i<=y;i++)
			s=s*x;
		return s;
	}

	public static double sqr_func (double x)
	{
		double s=x*x;
		return s;
	}

	public static long fact_func (int x)
	//Factorial method.	
	{
		long t=1;
		for(int i=x;i>0;i--)
			t=i*t;
		return t;
	}

} // END of class Math_class