Phoenix's Calculator
Java Source:
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
public class Calculator extends Applet implements ActionListener
{
/**************************
Data Members
***************************/
private TextField Panel; //To accept user input and display result
private Button Button0, //This button to pass 0 to panel
Button1, //This button to pass 1 to panel
Button2, //This button to pass 2 to panel
Button3, //This button to pass 3 to panel
Button4, //This button to pass 4 to panel
Button5, //This button to pass 5 to panel
Button6, //This button to pass 6 to panel
Button7, //This button to pass 7 to panel
Button8, //This button to pass 8 to panel
Button9, //This button to pass 9 to panel
ButtonDiv, //This button operate division
ButtonMul, //This button operate multiplication
ButtonAdd, //This button operate addition
ButtonSub, //This button opearte subtraction
ButtonAss, //This button return result
ButtonOpar, //This button call open parentheses
ButtonCpar, //This button call close parentheses
ButtonPoint, //This button to pass . to panel
ButtonClear; //This button clear panel
private int Flag, //Record the state after calculating
Err_lve; //State the error level
/*************************
Initialize similar like Constructor, that is use for Applet
**************************/
public void init()
{
setBackground(Color.white); //Set white backgroud
setLayout(null);
resize(205, 210);
Flag = 0;
Err_lve = 0;
Panel = new TextField();
Panel.setBounds( 20, 20, 165, 25);
add(Panel);
Button0 = new Button("0");
Button0.setBounds (20, 160, 25, 25);
add(Button0);
Button1 = new Button("1");
Button1.setBounds (20, 125, 25, 25);
add(Button1);
Button2 = new Button("2");
Button2.setBounds (55, 125, 25, 25);
add(Button2);
Button3 = new Button("3");
Button3.setBounds (90, 125, 25, 25);
add(Button3);
Button4 = new Button("4");
Button4.setBounds (20, 90, 25, 25);
add(Button4);
Button5 = new Button("5");
Button5.setBounds (55, 90, 25, 25);
add(Button5);
Button6 = new Button("6");
Button6.setBounds (90, 90, 25, 25);
add(Button6);
Button7 = new Button("7");
Button7.setBounds (20, 55, 25, 25);
add(Button7);
Button8 = new Button("8");
Button8.setBounds (55, 55, 25, 25);
add(Button8);
Button9 = new Button("9");
Button9.setBounds (90, 55, 25, 25);
add(Button9);
ButtonDiv = new Button("/");
ButtonDiv.setBounds (160, 90, 25, 25);
add(ButtonDiv);
ButtonMul = new Button("*");
ButtonMul.setBounds (125, 90, 25, 25);
add(ButtonMul);
ButtonAdd = new Button("+");
ButtonAdd.setBounds (125, 55, 25, 25);
add(ButtonAdd);
ButtonSub = new Button("-");
ButtonSub.setBounds (160, 55, 25, 25);
add(ButtonSub);
ButtonAss = new Button("=");
ButtonAss.setBounds (90, 160, 25, 25);
add(ButtonAss);
ButtonOpar = new Button("(");
ButtonOpar.setBounds (125, 125, 25, 25);
add(ButtonOpar);
ButtonCpar = new Button(")");
ButtonCpar.setBounds (160, 125, 25, 25);
add(ButtonCpar);
ButtonPoint = new Button(".");
ButtonPoint.setBounds (55, 160, 25, 25);
add(ButtonPoint);
ButtonClear = new Button("Clear");
ButtonClear.setBounds (125, 160, 60, 25);
add(ButtonClear);
Panel.addActionListener(this);
Button0.addActionListener(this);
Button1.addActionListener(this);
Button2.addActionListener(this);
Button3.addActionListener(this);
Button4.addActionListener(this);
Button5.addActionListener(this);
Button6.addActionListener(this);
Button7.addActionListener(this);
Button8.addActionListener(this);
Button9.addActionListener(this);
ButtonDiv.addActionListener(this);
ButtonMul.addActionListener(this);
ButtonAdd.addActionListener(this);
ButtonSub.addActionListener(this);
ButtonAss.addActionListener(this);
ButtonOpar.addActionListener(this);
ButtonCpar.addActionListener(this);
ButtonPoint.addActionListener(this);
ButtonClear.addActionListener(this);
}
/*
Method: paint
Purpose: Draw the outline of calculator *(this method can auto. draw when develop Applet, but it isn't Applet's method)
Parameters: Graphics
Returns: None
*/
public void paint(Graphics graphic)
{
graphic.setColor(Color.yellow);
graphic.drawRoundRect(0, 0, 190, 195, 15, 15);
graphic.setColor(Color.lightGray);
graphic.drawRoundRect(1, 1, 191, 196, 15, 15);
graphic.drawRoundRect(2, 2, 192, 197, 15, 15);
graphic.drawRoundRect(3, 3, 193, 198, 15, 15);
graphic.drawRoundRect(4, 4, 194, 199, 15, 15);
graphic.setColor(Color.black);
graphic.fillRoundRect(5, 5, 195, 200, 15, 15);
graphic.setColor(Color.green);
graphic.drawRoundRect(5, 5, 195, 200, 15, 15);
graphic.setColor(Color.yellow);
graphic.drawString("Phoenix's Calculator", 45, 200);
}
/*
Method: actionPerformed
Purpose: Event-handling
Parameters: Action event
Returns: None
*/
public void actionPerformed(ActionEvent event)
{
if (event.getSource() instanceof Button)
{
Button clickedButton = (Button) event.getSource();
if (clickedButton == ButtonClear)
{
ClearPanel();
Flag = 0;
}
else if (clickedButton == ButtonAss)
{
Err_lve = 0;
Compute();
Flag = 1;
}
else
{
if (Flag == 1)
{
ClearPanel(); //clear panel after calculation
Flag = 0;
}
DisplayEx(clickedButton);
}
}
else
{
Err_lve = 0;
Compute();
Flag = 1;
}
}
/*
Method: ClearPanel
Purpose: Clear Panel TextField objects
Parameters: None
Returns: None
*/
private void ClearPanel()
{
Panel.setText("");
}
/*
Method: DisplayEx
Purpose: Display the whole expression that the user enters
Parameters: clickedButton
Returns: None
*/
private void DisplayEx(Button ClickedButton)
{
String tmpstr;
tmpstr = Panel.getText();
if (ClickedButton == Button0) Panel.setText(tmpstr+"0");
if (ClickedButton == Button1) Panel.setText(tmpstr+"1");
if (ClickedButton == Button2) Panel.setText(tmpstr+"2");
if (ClickedButton == Button3) Panel.setText(tmpstr+"3");
if (ClickedButton == Button4) Panel.setText(tmpstr+"4");
if (ClickedButton == Button5) Panel.setText(tmpstr+"5");
if (ClickedButton == Button6) Panel.setText(tmpstr+"6");
if (ClickedButton == Button7) Panel.setText(tmpstr+"7");
if (ClickedButton == Button8) Panel.setText(tmpstr+"8");
if (ClickedButton == Button9) Panel.setText(tmpstr+"9");
if (ClickedButton == ButtonDiv) Panel.setText(tmpstr+"/");
if (ClickedButton == ButtonMul) Panel.setText(tmpstr+"*");
if (ClickedButton == ButtonAdd) Panel.setText(tmpstr+"+");
if (ClickedButton == ButtonSub) Panel.setText(tmpstr+"-");
if (ClickedButton == ButtonOpar)Panel.setText(tmpstr+"(");
if (ClickedButton == ButtonCpar)Panel.setText(tmpstr+")");
if(ClickedButton == ButtonPoint)Panel.setText(tmpstr+".");
}
/*
Method: Compute
Purpose: Calculate the expression and shown the result, when the user hit return key or "=" button.
Parameters: The whole expression
Returns: None
*/
private void Compute()
{
String Tmpstr, Result="";
char ch;
int i, no_of_char,
no_of_par = 0;
Tmpstr = Panel.getText();
no_of_char = Tmpstr.length();
//Expression brief checking
for (i = 0; i < no_of_char; i++)
{
ch = Tmpstr.charAt(i);
if (ch == ')') no_of_par--;
if (no_of_par < 0) Err_lve = 1;
if (ch == '(') no_of_par++;
if (ch < '(' || ch > '9' || ch == ',') Err_lve = 2;
if (ch == '.' && (i+1 < Tmpstr.length()) )
for ( int j = i+1; (j < Tmpstr.length()) && ((Character.isDigit(Tmpstr.charAt(j))) || ((Tmpstr.charAt(j))) == '.'); j++ )
if (Tmpstr.charAt(j) == '.') Err_lve = 3;
//If an operand has more than one point return error
}//End of expression brief checking
if (no_of_par != 0) Err_lve = 1; //If open and close parentheses do not match return error
if (Err_lve != 0) Err_msg(Err_lve); //An error perform to prompt error message
else Result = Calculate(Tmpstr); //No error perform to calculate expression
if (Err_lve != 0) Err_msg(Err_lve); //An error perform to prompt error message
else Panel.setText(Result); //No error show result
}
/*
Method: Calculate
Purpose: Implement the expression
Parameters: Expression
Returns: None
*/
private String Calculate(String expression)
{
String result = expression, f_operand, r_operand;
char cha;
int index, f_index, r_index,
no_of_cha = result.length(),
no_of_pare = 0, pare_match = 0, op_index = 0, cp_index = 0;
if (Err_lve == 0)
{
//Checking Parentheses
for (index = 0; index < no_of_cha; index++)
{
cha = result.charAt(index);
if (cha == '(')
{
if (pare_match == 0) op_index = index;
pare_match ++;
no_of_pare ++;
}
if (cha == ')')
{
pare_match --;
if (pare_match == 0) cp_index = index;
}
}//End of checking Parentheses
if (op_index+1 == cp_index) Err_lve = 3;
//Recursive Calculate, when parentheses existed
if (Err_lve == 0 && no_of_pare > 0)
{
if ((op_index == 0) && (cp_index == (no_of_cha - 1)) && (op_index != cp_index)) result = Calculate(result.substring(op_index + 1, cp_index));
else if (op_index == 0 && cp_index > 0)
{
if ( (Character.isDigit(result.charAt(cp_index+1))) ) Err_lve = 3;
else
{
result = Calculate(result.substring(op_index + 1, cp_index)) + result.substring(cp_index + 1);
no_of_pare--;
while(no_of_pare != 0)
{
result = Calculate(result);
no_of_pare--;
}
}
}
else if ((op_index > 0) && (cp_index > 0) && (cp_index != no_of_cha -1))
{
if ( (Character.isDigit(result.charAt(cp_index+1))) || (Character.isDigit(result.charAt(op_index-1))) ) Err_lve = 3;
else
{
result = result.substring(0, op_index) + Calculate(result.substring(op_index +1, cp_index)) + result.substring(cp_index +1);
no_of_pare--;
while(no_of_pare != 0)
{
result = Calculate(result);
no_of_pare--;
}
}
}
else if (cp_index == no_of_cha -1 && op_index > 0)
{
if ( (Character.isDigit(result.charAt(op_index-1))) ) Err_lve = 3;
else
{
result = result.substring(0, op_index) + Calculate(result.substring(op_index + 1, cp_index));
no_of_pare--;
while(no_of_pare != 0)
{
result = Calculate(result);
no_of_pare--;
}
}
}
}//End of recursive Calculate statement
//Implement algorithm
if (no_of_pare == 0 && Err_lve == 0)
{
if ( (!(Character.isDigit(result.charAt(0))) && (result.charAt(0) != '-')) || !(Character.isDigit(result.charAt(result.length()-1))) ) Err_lve = 3;
//Implement multiply and divide first
for (index = 0; index < result.length() && (Err_lve == 0); index++)
{
cha = result.charAt(index);
if (cha == '*' || cha == '/')
{
if ( !(Character.isDigit(result.charAt(index-1))) || ( !(Character.isDigit(result.charAt(index+1))) && (result.charAt(index+1) != '-') ) ) Err_lve = 3;
if (result.charAt(index+1) == '-')
if ( !(Character.isDigit(result.charAt(index+2))) ) Err_lve = 3;
if (Err_lve == 0)
{
f_index = index - 1;
if (f_index > 2)
if ( ((result.charAt(f_index-1)) == '-') && ((result.charAt(f_index-2)) == 'E') )
f_index = f_index - 2;
while ( (f_index > 0) && ((Character.isDigit(result.charAt(f_index-1))) || ((result.charAt(f_index-1)) == '.') || ((result.charAt(f_index-1)) == 'E')) )
{
f_index--;
}
if (f_index ==1)
if ((result.charAt(f_index-1)) == '-')
f_index--;
if (f_index > 2)
if ( ((result.charAt(f_index-1)) == '-') && !(Character.isDigit(result.charAt(f_index-2))) )
f_index--;
f_operand = result.substring(f_index, index);
r_index = index + 1;
while ( (r_index < result.length()-1) && ((Character.isDigit(result.charAt(r_index+1))) || ((result.charAt(r_index+1)) == '.') || ((result.charAt(r_index+1)) == 'E')) )
{
r_index++;
if (r_index < result.length()-2)
if ( ((result.charAt(r_index)) == 'E') && ((result.charAt(r_index+1)) == '-') )
r_index++;
}
r_operand = result.substring(index+1, r_index+1);
if ( (f_index != 0) && (r_index != result.length()-1) )
{
if (Algorithm(cha, f_operand, r_operand).charAt(0) == 'N') Err_lve = 4; //If an answer is not a number return error
if (Algorithm(cha, f_operand, r_operand).charAt(0) == 'I') Err_lve = 5; //If an answer is Infinity return error
result = result.substring(0, f_index) + Algorithm(cha, f_operand, r_operand) + result.substring(r_index+1);
index = 0;
}
else if ( (f_index == 0) && (r_index == result.length()-1) )
{
if (Algorithm(cha, f_operand, r_operand).charAt(0) == 'N') Err_lve = 4; //If an answer is not a number return error
if (Algorithm(cha, f_operand, r_operand).charAt(0) == 'I') Err_lve = 5; //If an answer is Infinity return error
result = Algorithm(cha, f_operand, r_operand);
}
else if (f_index == 0)
{
if (Algorithm(cha, f_operand, r_operand).charAt(0) == 'N') Err_lve = 4; //If an answer is not a number return error
if (Algorithm(cha, f_operand, r_operand).charAt(0) == 'I') Err_lve = 5; //If an answer is Infinity return error
result = Algorithm(cha, f_operand, r_operand) + result.substring(r_index+1);
index = 0;
}
else if (r_index == result.length()-1)
{
if (Algorithm(cha, f_operand, r_operand).charAt(0) == 'N') Err_lve = 4; //If an answer is not a number return error
if (Algorithm(cha, f_operand, r_operand).charAt(0) == 'I') Err_lve = 5; //If an answer is Infinity return error
result = result.substring(0, f_index) + Algorithm(cha, f_operand, r_operand);
}
}
}
}//End of implement multiply and divide
//Implement add and subtract
for (index = 0; index < result.length() && (Err_lve == 0); index++)
{
if (index == 0 && result.charAt(index) == '-') index = 1;
if (index > 0)
if ( ((result.charAt(index)) == 'E') && ((result.charAt(index+1)) == '-') )
index = index + 2;
cha = result.charAt(index);
if (cha == '+' || cha == '-')
{
if ( !(Character.isDigit(result.charAt(index-1))) || ( !(Character.isDigit(result.charAt(index+1))) && (result.charAt(index+1) != '-') ) ) Err_lve = 3;
if (result.charAt(index+1) == '-')
if ( !(Character.isDigit(result.charAt(index+2))) ) Err_lve = 3;
if (Err_lve == 0)
{
f_index = 0;
f_operand = result.substring(f_index, index);
r_index = index + 1;
while ( (r_index < result.length()-1) && ((Character.isDigit(result.charAt(r_index+1))) || ((result.charAt(r_index+1)) == '.') || ((result.charAt(r_index+1)) == 'E')) )
{
r_index++;
if (r_index < result.length()-2)
if ( ((result.charAt(r_index)) == 'E') && ((result.charAt(r_index+1)) == '-') )
r_index++;
}
r_operand = result.substring(index+1, r_index+1);
result = Algorithm(cha, f_operand, r_operand) + result.substring(r_index+1);
index = 0;
}
}
}//End of implement add and subtract
}//End of implement algorithm
}
return result;
}
/*
Method: Algorithm
Purpose: Implement the simple expression
Parameters: Operator, front value and rear value
Returns: None
*/
private String Algorithm(char Operator, String F_operand, String R_operand)
{
Double F, R;
double f, r,
ans = 0;
String res;
F = new Double(F_operand);
R = new Double(R_operand);
f = F.doubleValue();
r = R.doubleValue();
if (Operator == '+') ans = f + r;
if (Operator == '-') ans = f - r;
if (Operator == '*') ans = f * r;
if (Operator == '/') ans = f / r;
res = Double.toString(ans);
return res;
}
/*
Method: Err_msg
Purpose: Prompt error message
Parameters: Error level
Returns: None
*/
private void Err_msg(int Err_lve)
{
switch(Err_lve)
{
case 1:
Panel.setText("Parentheses do not match");
break;
case 2:
Panel.setText("Invalid input");
break;
case 3:
Panel.setText("Invalid expression");
break;
case 4:
Panel.setText("Not a number exist");
break;
case 5:
Panel.setText("Infinity exist");
break;
default:
Panel.setText("Unknow error");
break;
}
}
}
/*... End of Calculator.java ...*/
Back to Calculator
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