import java.awt.*;
import java.awt.event.*;
import java.awt.Graphics;
import ETextField;
public class AwtCalc extends java.applet.Applet implements ActionListener
{
private Button[] buttons = new Button[19];
private String[] buttonText = { " 1 ", " 2 ", " 3 ", " + ", " - ",
" 4 ", " 5 ", " 6 ", " x ", " / ",
" 7 ", " 8 ", " 9 ", "^ ", "sqrt",
" C ", " 0 ", " . ", " = "};
private ETextField result; // Calculator display screen
private String input = ""; // stores user input
private Label label;
private Color forecolor, // Calculator foreground color
backcolor, // Calculator background color
fieldcolor; // the display screen's color
private Font font,
buttonfont;
private int oper = 0, // stores the integer constants representing
oldoper = 0, // the operators
newoper = 0;
private double answer,
num1 = 0.0,
num2 = 0.0,
num3 = 0.0;
private final int ADD=1, // integer constants representing operators
SUB = 2,
MULT = 3,
DIVI = 4,
POW = 5,
SQRT = 6;
private boolean firstpress = true, //determines first button press
morenums = false, //"" if more numbers are being pressed
equals = false, //"" if equal button has been pressed
clearscreen = false, //clears screen
decnumber = false, //"" if a user entered a float
doubleclick = false; //"" if mouse was doubleclicked
public void init() {
font = new Font( "Courier", Font.ITALIC, 10 );
buttonfont = new Font( "Courier", Font.PLAIN, 12 );
setBackground( Color.lightGray );
//initialize colors
result = new ETextField( 125, 18 );
label = new Label( "AWT Calculator" );
setLayout( new FlowLayout() );
add( result );
add( label );
//initialize and add buttons
for ( int i = 0; i < 19; i++ ) {
buttons[i] = new Button( buttonText[i] );
buttons[i].setFont( buttonfont );
buttons[i].addActionListener( this );
if ( i <= 2 )
add( buttons[i] );
else if ( i >= 3 && i <= 7)
add( buttons[i] );
else if ( i >=8 && i <= 12 )
add( buttons[i] );
else if ( i >= 13 && i <= 17 )
add( buttons[i] );
else
add( buttons[i] );
if ( i == 2 )
add( new Label( " " ) );
else if ( i == 7 )
add( new Label( " " ) );
else if ( i == 12 )
add( new Label( " " ) );
else if ( i == 17 )
add( new Label( " " ) );
}
buttons[15].setForeground( Color.red );
result.setBackground( Color.white );
label.setFont( font );
}
//==============================================================================
// Interface method that determines which button was pressed then determines
// the appropriate action.
//==============================================================================
public void actionPerformed( ActionEvent e )
{
// "if" block is not entered if the button is an operator
if ( e.getSource() != buttons[3] && e.getSource() != buttons[4]
&& e.getSource() != buttons[8] && e.getSource() != buttons[9]
&& e.getSource() != buttons[13] && e.getSource() != buttons[14]
&& e.getSource() != buttons[15] && e.getSource() != buttons[18] ) {
if ( clearscreen ) { // clears screen if user enters number before an
clearScreen(); // operator after pressing equals
clearscreen = false;
}
if ( e.getSource() == buttons[0] ) {
input += "1"; // concoctenate "1" to input
result.setText( input );
showAnswer( input );
} // end else if
else if ( e.getSource() == buttons[1] ) {
input += "2"; // concoctenate "2" to input
showAnswer( input );
} // end else if
else if ( e.getSource() == buttons[2] ) {
input += "3"; // concoctenate "3" to input
showAnswer( input );
} // end else if
else if ( e.getSource() == buttons[5] ) {
input += "4"; // concoctenate "4" to input
showAnswer( input );
} // end else if
else if ( e.getSource() == buttons[6] ) {
input += "5"; // concoctenate "5" to input
showAnswer( input );
} // end if
else if ( e.getSource() == buttons[7] ) {
input += "6"; // concoctenate "6" to input
showAnswer( input );
} // end else if
else if ( e.getSource() == buttons[10] ) {
input += "7"; // concoctenate "7" to input
showAnswer( input );
} // end else if
else if ( e.getSource() == buttons[11] ) {
input += "8"; // concoctenate "8" to input
showAnswer( input );
} // end else if
else if ( e.getSource() == buttons[12] ) {
input += "9"; // concoctenate "9" to input
showAnswer( input );
} // end else if
else if ( e.getSource() == buttons[16] ) {
input += "0"; // concoctenate "0" to input
showAnswer( input );
} // end else if
else if ( e.getSource() == buttons[17] ) {
if ( decnumber == false ) {
decnumber = true;
input += ".0"; // concoctenate "." to input
showAnswer( input );
}
}
} // end if
// check if user entered the addition operator
if ( e.getSource() == buttons[3] ) {
clearscreen = false;
decnumber = false;
oper = ADD; // oper is set to addition
clickCheck( input ); // checks if user doubleclicked
if ( doubleclick == false )
processNumbers(); // if no double click continue to process
input = ""; // clear variable to store new input
} // end if
// check if user entered the subtraction operator
else if (e.getSource() == buttons[4] ) {
clearscreen = false;
decnumber = false;
oper = SUB; // oper is set to subtraction
clickCheck( input ); // check if user doubleclicked
if ( doubleclick == false )
processNumbers(); // if no double click continue to process
input = ""; // clear variable to store new input
} // end else if
// check if user entered the multiplication operator
else if (e.getSource() == buttons[8] ) {
clearscreen = false;
decnumber = false;
oper = MULT; // oper is set to multiplication
clickCheck( input ); // check if user doubleclicked
if ( doubleclick == false )
processNumbers(); // if no double click continue to process
input = ""; // clear variable to store new input
} //end else if
// check if user entered the divide operator
else if (e.getSource() == buttons[9] ) {
clearscreen = false;
decnumber = false;
oper = DIVI; // oper is set to divide
clickCheck( input ); // check if user doubleclicked
if ( doubleclick == false )
processNumbers(); // if no double click continue to process
input = ""; // clear variable to store new input
} // end else if
// check if user entered the exponential operator
else if ( e.getSource() == buttons[13] ) {
clearscreen = false;
decnumber = false;
oper = POW; // oper is set to exponential
clickCheck( input ); // check if user doubleclicked
if ( doubleclick == false )
processNumbers(); // if no double click continue to process
input = ""; // clear variable to store new input
} // end else if
// check if user entered the square root operator
else if ( e.getSource() == buttons[14] ) {
clearscreen = false;
oper = SQRT; // oper is set to square root
clickCheck( input ); // check if user doubleclicked
if ( doubleclick == false )
processNumbers(); // if no double click continue to process
input = ""; // clear variable to store new input
} // end else if
// check if user entered the clear operator
if (e.getSource() == buttons[15] ) {
clearScreen();
} // end if
// check if user entered the equal operator
if (e.getSource() == buttons[18] ) {
equals = true;
clearscreen = true;
clickCheck( input ); //check if user double-clicked
if ( doubleclick == false )
processNumbers(); //continue to process numbers if
input = Double.toString( answer ); //if no double-click
} // end if
} // end actionPerformed()
//==============================================================================
//Method processNumbers is where processes the numbers inputed by the user
//==============================================================================
public void processNumbers() {
// the program enters this "if" block when an operator is pressed for the
// first time
if ( firstpress ) {
if ( equals ) {
num1 = answer; //answer is stored in num1 if user enters equal operator
equals = false; // equals is set to false to allow additional input
} // end if
else
num1 = Double.valueOf( input ).doubleValue(); // converts a string number to double
oldoper = oper; // store current operator to oldoper
// if operator is square root, calculation and output is done immediately
if ( oper == SQRT ) {
answer = calculate( oldoper, num1, 0.0 );
showAnswer( Double.toString( answer ) );
morenums = true;
}
firstpress = false; // no longer the first operator
} // end if
// "if" block is entered if now more than two numbers are being entered to
// be calculated
else if ( !morenums ) {
num2 = Double.valueOf( input ).doubleValue(); //converts second num to double
answer = calculate( oldoper, num1, num2 ); //calculate num1 and num2 with
showAnswer( Double.toString( answer) ); //the past operator
newoper = oper; //store current operator to
//new oper
if ( !equals )
morenums = true; //tells program that more than two numbers have
else { //entered
morenums = false; //if equal operator is pressed, firstpress
firstpress = true; //returns to true
} // end else
} // end if
// if more than two numbers are being inputted to calculate, this "if" block
// is accessed
else if (morenums) {
if ( equals ) {
newoper = oper;
morenums = false;
firstpress = true; // if equals is pressed set firstpress to false
} // end if
num3 = Double.valueOf( input ).doubleValue();
answer = calculate( newoper, answer, num3 );
showAnswer( Double.toString(answer) );
newoper = oper;
} // end else if
} // end processNumbers()
//==============================================================================
//Method calculate determines which operator was entered and calculates
//two numbers depending on the operator pressed
//==============================================================================
public double calculate( int oper, double number1, double number2 )
{
double answer = 0.0;
switch( oper ) {
case ADD:
answer = number1 + number2;
break;
case SUB:
answer = number1 - number2;
break;
case MULT:
answer = number1 * number2;
break;
case DIVI:
answer = number1 / number2;
break;
case POW:
answer = Math.pow( number1, number2 );
break;
case SQRT:
answer = Math.sqrt( number1 );
break;
} // end switch
return answer;
} // end calculate()
//==============================================================================
//Method showAnswer outputs the results in the calculators displays screen
//==============================================================================
public void showAnswer( String s )
{
double answer;
answer = Double.valueOf(s).doubleValue();
if ( decnumber )
result.setText( Double.toString(answer) );
else
result.setText( s ); //all output are displayed as integers at start
} // end showAnswer
//==============================================================================
//Method clickCheck determines if the user double clicked and returns a boolean
//value. If doubleclick is true, the program ignores the input
//==============================================================================
public boolean clickCheck( String s ) {
if ( s == "" )
doubleclick = true;
else
doubleclick = false;
return doubleclick;
}
//==============================================================================
//Method clearScreen clears calculator display screen and sets variables to
//default.
//==============================================================================
public void clearScreen()
{
oper = 0; // reinitialize variables to default
input = "";
answer = 0;
decnumber = false;
morenums = false;
firstpress = true;
equals = false;
showAnswer( Integer.toString( (int)answer) );
}
public void paint( Graphics g )
{
//draw border
g.drawRect( 0, 0, size().width - 1, size().height - 1 );
g.drawLine( 0, 0, 0, size().height );
}
} // end program
