I just wanna test my event,but it doesnt work,anything wrong?
Pls help...thanks..
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
class Frame extends JFrame
{
private static final Font numFont = new Font("monspaced", Font.PLAIN, 14);
private static final Font font = new Font("monspaced", Font.PLAIN, 14);
private JTextField displayField; // display result / input.
//... Variables representing state of the calculator
String Status; //String to hold the status of various parts
//of the program
boolean OperatorKey; //the 'flag' that will signify whether or not any
//operator button has been pressed
boolean FunctionKey; //the 'flag' that will signify whether or not any f
//function button has been pressed
int Counter; //counts the number of digits entered
double Result; //the answer displayed, as well as the second
//operator taken for an operation
int Operator; //an integer value to indicate which operator
//button was pressed
double Operand; //the first number entered for an operation
double Mem; //the variable which holds whatever value the user
//wants kept in "memory"
boolean DecimalFlag; //the 'flag' that will signify whether or not the
//decimal button has been pressed
boolean SignFlag; //the 'flag' that will signify whether or not the
//plus/minus button has been pressed
JButton button1 = new JButton("1");
JButton button2 = new JButton("2");
JButton button3 = new JButton("3");
JButton button4 = new JButton("4");
JButton button5 = new JButton("5");
JButton button6 = new JButton("6");
JButton button7 = new JButton("7");
JButton button8 = new JButton("8");
JButton button9 = new JButton("9");
JButton button0 = new JButton("0");
JButton buttonDecimal = new JButton(".");
JButton buttonMinus = new JButton("-");
JButton buttonMultiply = new JButton("x");
JButton buttonPlus = new JButton("+");
JButton buttonEquals = new JButton("=");
JButton buttonDivide = new JButton("/");
JButton buttonClear = new JButton("C");
JButton buttonMPlus = new JButton("M+");
JButton buttonMClear = new JButton("MC");
JButton buttonMR = new JButton("MR");
JButton buttonPercent = new JButton("%");
JButton buttonOneOverX = new JButton("1/X");
JButton buttonSqr = new JButton("sq");
JButton buttonSqrRoot = new JButton("sqrt");
//This label will display all error messages
JLabel errorMsg = new JLabel(" ");
/* This label is just to the left of the Display Label displayField, and will
* indicate whether or not a value is being held in the calculator's "memory"
*/
Label LabelMem = new Label(" ",Label.RIGHT);
public static void main(String[] args)
{
//... Set the Look and Feel to that of system we're running on.
try
{
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
}
catch (Exception unused)
{
; // Ignore exception because we can't do anything. Will use default.
}
//... Create the window.
Frame window = new Frame();
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setVisible(true);
}
public Frame()
{
//... Set attributes of the display field
displayField = new JTextField("0", 12);
displayField.setHorizontalAlignment(JTextField.RIGHT);
displayField.setFont(font);
//... Use one listener for all numeric keys.
ActionListener numListener = new NumListener();
//... Layout numeric keys in a grid. Generate the buttons
// in a loop from the chars in a string.
JPanel buttonPanel = new JPanel();
buttonPanel.setLayout(new GridLayout(5, 3, 2, 2));
// This is the declaration of all numeric buttons to be used in the applet
button1.addActionListener(numListener);
button1.setFont(numFont);
buttonPanel.add(button1);
button2.addActionListener(numListener);
button2.setFont(numFont);
buttonPanel.add(button2);
button3.addActionListener(numListener);
button3.setFont(numFont);
buttonPanel.add(button3);
button4.addActionListener(numListener);
button4.setFont(numFont);
buttonPanel.add(button4);
button5.addActionListener(numListener);
button5.setFont(numFont);
buttonPanel.add(button5);
button6.addActionListener(numListener);
button6.setFont(numFont);
buttonPanel.add(button6);
button6.addActionListener(numListener);
button6.setFont(numFont);
buttonPanel.add(button6);
button7.addActionListener(numListener);
button7.setFont(numFont);
buttonPanel.add(button7);
button8.addActionListener(numListener);
button8.setFont(numFont);
buttonPanel.add(button8);
button9.addActionListener(numListener);
button9.setFont(numFont);
buttonPanel.add(button9);
button0.addActionListener(numListener);
button0.setFont(numFont);
buttonPanel.add(button0);
buttonDecimal.addActionListener(numListener);
buttonDecimal.setFont(numFont);
buttonPanel.add(buttonDecimal);
//... Create panel with gridlayout to hold operator buttons.
JPanel opPanel1 = new JPanel();
opPanel1.setLayout(new GridLayout(4, 2, 2, 2));
buttonPlus.addActionListener(numListener);
buttonPlus.setFont(font);
opPanel1.add(buttonPlus);
buttonMinus.addActionListener(numListener);
buttonMinus.setFont(font);
opPanel1.add(buttonMinus);
buttonMultiply.addActionListener(numListener);
buttonMultiply.setFont(font);
opPanel1.add(buttonMultiply);
buttonDivide.addActionListener(numListener);
buttonDivide.setFont(font);
opPanel1.add(buttonDivide);
buttonEquals.addActionListener(numListener);
buttonEquals.setFont(font);
opPanel1.add(buttonEquals);
buttonSqr.addActionListener(numListener);
buttonSqr.setFont(font);
opPanel1.add(buttonSqr);
buttonPercent.addActionListener(numListener);
buttonPercent.setFont(font);
opPanel1.add(buttonPercent);
buttonOneOverX.addActionListener(numListener);
buttonOneOverX.setFont(font);
opPanel1.add(buttonOneOverX);
JPanel opPanel2 = new JPanel();
opPanel2.setLayout(new GridLayout(4, 1, 2, 2));
buttonMPlus.addActionListener(numListener);
buttonMPlus.setFont(font);
opPanel2.add(buttonMPlus);
buttonMClear.addActionListener(numListener);
buttonMClear.setFont(font);
opPanel2.add(buttonMClear);
buttonMR.addActionListener(numListener);
buttonMR.setFont(font);
opPanel2.add(buttonMR);
buttonMPlus.addActionListener(numListener);
buttonMPlus.setFont(font);
opPanel2.add(buttonMPlus);
JPanel msgPanel = new JPanel();
msgPanel.add(errorMsg);
//... Layout the top-level content panel.
JPanel content = new JPanel();
content.setLayout(new BorderLayout(5, 5));
content.add(displayField, BorderLayout.NORTH );
content.add(buttonPanel , BorderLayout.CENTER);
content.add(opPanel1 , BorderLayout.EAST);
content.add(opPanel2 , BorderLayout.WEST);
content.add(msgPanel , BorderLayout.SOUTH);
content.setBorder(BorderFactory.createEmptyBorder(10,10,10,10));
//... Finish building the window (JFrame)
this.setContentPane(content);
this.pack();
this.setTitle("Calculator");
this.setResizable(false);
this.setLocationRelativeTo(null);
Clicked_Clear();
}//end constructor
/* The following integer values are being set as "final" because
* they are going to be used for determining what button has been
* pushed
*/
public final static int OpMinus=11,
OpMultiply=12,
OpPlus=13,
OpDivide=15,
OpMPlus=19,
OpMClear=20,
OpMR=21;
class NumListener implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
/* Declares an object named "src" to represent the event.getSource()
* method. This shortens the code that follows.
*/
Object src = event.getSource();
/* Checks to see if the source of the event which src is representing
* * is a Button and can behave like a Button
* * */
if (src instanceof Button)
{
/* Checks to see if Status string holds the value ERROR OR if the
* * source of the event is the buttonClear ("C") button
* * */
if ((Status != "ERROR") || (src == buttonClear))
{
/* The following conditions check for numeric buttons that have
* been pressed, and then called the method NumericButton and
* send it an integer value depending on the value of the button
* pressed
*/
if (src == button1)
{
NumericButton(1);
}
if (src == button2)
{
NumericButton(2);
}
if (src == button3)
{
NumericButton(3);
}
if (src == button4)
{
NumericButton(4);
}
if (src == button5)
{
NumericButton(5);
}
if (src == button6)
{
NumericButton(6);
}
if (src == button7)
{
NumericButton(7);
}
if (src == button8)
{
NumericButton(8);
}
if (src == button9)
{
NumericButton(9);
}
if (src == button0)
{
NumericButton(0);
}
/* The following conditions check for operator buttons that have
* been pressed, and then call the OperatorButton method, sending
* the corresponding integer value
*/
if (src == buttonMinus)
{
OperatorButton(11);
}
if (src == buttonMultiply)
{
OperatorButton(12);
}
if (src == buttonPlus)
{
OperatorButton(13);
}
if (src == buttonEquals)
{
OperatorButton(14);
}
if (src == buttonDivide)
{
OperatorButton(15);
}
/* This condition checks if the decimal button has been pressed,
* and then calls the DecimalButton method
*/
if (src == buttonDecimal)
{
DecimalButton();
}
/* This condition checks if the percent button has been pressed,
* and then calls the PercentButton method
*/
if (src == buttonPercent)
{
PercentButton();
}
/* This condition checks if the clear button has been pressed,
* and then calls the Clicked_Clear method
*/
if (src == buttonClear)
{
Clicked_Clear();
}
/* This condition checks if the Plus Minus Button has been
* pressed, and then calls the PlusMinusButton method
*/
//------if (src == buttonNegative)
//------{
//------ PlusMinusButton();
//------}
/* This condition checks if the Square Button has been pressed,
* and then calls the SqrButton method
*/
if (src == buttonSqr)
{
SqrButton();
}
/* This condition checks if the Square Root Button has been
* pressed, and then calls the SqrRootButton method
*/
if (src == buttonSqrRoot)
{
SqrRootButton();
}
/* This condition checks if the One over X Button has been
* pressed, and then calls the OneOverXButton method
*/
if (src == buttonOneOverX)
{
OneOverXButton();
}
/* These conditions checks to see if any of the Memory Buttons
* have been pressed, and then calls the MemoryButton method and
* sends them the corresponding integer values
*/
if (src == buttonMPlus)
{
MemoryButton(19);
}
if (src == buttonMClear)
{
MemoryButton(20);
}
if (src == buttonMR)
{
MemoryButton(21);
}
}
}
}
/* This method is called whenever a numeric button (0-9) is pushed. */
public void NumericButton(int i)
{
DisplayError(" "); //Clears the error message field
/* Declares a String called Display that will initialize to whatever
* is currently displayed in the lcdDisplay of the calculator
*/
String Display = displayField.getText();
/* Checks if an operator key has just been pressed, and if it has,
* then the limit of 20 digits will be reset for the user so that
* they can enter in up to 20 new numbers
*/
if (OperatorKey == true)
{
Counter = 0;
}
Counter = Counter + 1; //increments the counter
/* This is a condition to see if the number currently displayed is zero OR
* an operator key other than +, -, *, or / has been pressed.
*/
if ((Display == "0") || (Status == "FIRST"))
{
Display= ""; //Do not display any new info
}
if (Counter < 21) //if more than 20 numbers are entered
{
//The number just entered is appended to the string currently displayed
Display = Display + String.valueOf(i);
}
else
{
//call the DisplayError method and send it an error message string
DisplayError("Digit Limit of 20 Digits Reached");
}
displayField.setText(Display); //sets the text of the displayField
//Label
Status = "VALID"; //sets the Status string to valid
OperatorKey = false; //no operator key was pressed
FunctionKey = false; //no function key was pressed
}
/* This method is called whenever an operator button is pressed, and is
* sent an integer value representing the button pressed.
*/
public void OperatorButton(int i)
{
DisplayError(" "); //Clears the error message field
/* Creates a new Double object with the specific purpose of retaining
* the string currently on the displayField label, and then immediately
* converts that string into a double-precision real number and then
* gives that number to the variable Result.
*/
Result = (new Double(displayField.getText())).doubleValue();
//If no operator key has been pressed OR a function has been pressed
if ((OperatorKey == false) || (FunctionKey = true))
{
switch (Operator) //depending on the operation performed
{
/* if the user pressed the addition button, add the two numbers
* and put them in double Result
*/
case OpPlus : Result = Operand + Result;
break;
/* if the user pressed the subtraction button, subtract the two
* numbers and put them in double Result
*/
case OpMinus : Result = Operand - Result;
break;
/* if the user pressed the multiplication button, multiply
* the two numbers and put them in double Result
*/
case OpMultiply : Result = Result * Operand;
break;
/* if the user pressed the division button, check to see if
* the second number entered is zero to avoid a divide-by-zero
* exception
*/
case OpDivide : if (Result == 0)
{
//set the Status string to indicate an
//an error
Status = "ERROR";
//display the word "ERROR" on the
//lcdDisplay label
displayField.setText("ERROR");
/* call the DisplayError method and
* send it a string indicating an error
* has occured and of what type
*/
DisplayError("ERROR: Division by Zero");
}
else
{
//divide the two numbers and put the
//answer in double Result
Result = Operand / Result;
}
}
//if after breaking from the switch the Status string is not set
//to "ERROR"
if (Status != "ERROR")
{
Status = "FIRST"; /* set the Status string to "FIRST" to
* indicate that a simple operation was
* not performed
*/
Operand = Result; //Operand holds the value of Result
Operator = i; /* the integer value representing the
* operation being performed is stored
* in the integer Operator
*/
//The lcdDisplay label has the value of double Result
//displayed
displayField.setText(String.valueOf(Result));
//The boolean decimal flag is set false, indicating that the
//decimal button has not been pressed
DecimalFlag = false;
//The boolean sign flag is set false, indicating that the sign
//button has not been pressed
SignFlag = false;
//The boolean OperatorKey is set true, indicating that a simple
//operation has been performed
OperatorKey = true;
//The boolean FunctionKey is set false, indicating that a
//function key has not been pressed
FunctionKey = false;
DisplayError(" "); //Clears the error message field
}
}
} //end of OperatorButton method
/* This is a method that is called whenever the decimal button is
* pressed.
*/
public void DecimalButton()
{
DisplayError(" "); //Clears the error message field
/* Declares a String called Display that will initialize to whatever
* is currently displayed in the displayField of the calculator
*/
String Display = displayField.getText();
//if a simple operation was performed successfully
if (Status == "FIRST")
{
Display = "0"; //set Display string to character 0
}
//If the decimal button has not already been pressed
if (!DecimalFlag)
{
//appends a decimal to the string Display
Display = Display + ".";
}
else
{
/* calls the DisplayError method, sending a string
* indicating that the number already has a decimal
*/
DisplayError("Number already has a Decimal Point");
}
/* calls the setText method of the Label lcdDisplay and
* sends it the string Display
*/
displayField.setText(Display);
DecimalFlag = true; //the decimal key has been pressed
Status = "VALID"; /* Status string indicates a valid
* operation has been performed
*/
OperatorKey = false; //no operator key has been pressed
} //end of the DecimalButton method
/* This method is called whenever the percent button is pressed
*/
void PercentButton()
{
DisplayError(" "); //clears the error message field
/* Declares a String called Display that will initialize to whatever
* is currently displayed in the lcdDisplay of the calculator
*/
String Display = displayField.getText();
/* if the Status string is not set to "FIRST" OR the Display string
* does not currently hold the value "0"
*/
if ((Status != "FIRST") || (Display != "0"))
{
/* Creates a new Double object with the specific purpose of retaining
* the string currently on the lcdDisplay label, and then immediately
* converts that string into a double-precision real number and then
* gives that number to the variable Result.
*/
Result = (new Double(displayField.getText())).doubleValue();
//divide the double Result by 100, getting the percentage
Result = Result / 100;
/* call the setText method of Label lcdDisplay and send it the string
* that represents the value in Result
*/
displayField.setText(String.valueOf(Result));
Status = "FIRST"; //
OperatorKey = true; //an operator key has been pressed
FunctionKey = true; //a function key has been pressed
}
} //end of the PercentButton method
/* This method is called first when the calculator is initialized
* with the init() method, and is called every time the "C" button
* is pressed
*/
/* This method is called whenever the sign button is pressed */
void PlusMinusButton()
{
DisplayError(" "); //clears the error message field
/* Declares a String called Display that will initialize to whatever
* is currently displayed in the lcdDisplay of the calculator
*/
String Display = displayField.getText();
/* if Status is not set to FIRST and the Display string does not
* hold the value "0"
*/
if ((Status != "FIRST") || (Display != "0"))
{
/* Creates a new Double object with the specific purpose of retaining
* the string currently on the lcdDisplay label, and then immediately
* converts that string into a double-precision real number and then
* gives that number to the variable Result.
*/
Result = (new Double(displayField.getText())).doubleValue();
//sets the double Result to it's negative value
Result = -Result;
/* call the setText method of Label lcdDisplay and send it the string
* that represents the value in Result
*/
displayField.setText(String.valueOf(Result));
Status = "VALID"; //sets Status string to VALID
SignFlag = true; //the sign button has been pressed
DecimalFlag = true; //a decimal has appeared
}
} //end of the PlusMinusButton method
/* This method is called whenever the square button is pressed */
void SqrButton()
{
DisplayError(" "); //clears the error message field
/* Declares a String called Display that will initialize to whatever
* is currently displayed in the lcdDisplay of the calculator
*/
String Display = displayField.getText();
/* if Status is not set to FIRST and the Display string does not
* hold the value "0"
*/
if ((Status != "FIRST") || (Display != "0"))
{
/* Creates a new Double object with the specific purpose of retaining
* the string currently on the lcdDisplay label, and then immediately
* converts that string into a double-precision real number and then
* gives that number to the variable Result.
*/
Result = (new Double(displayField.getText())).doubleValue();
/* multiply the double Result by itself, effectively squaring
* the number */
Result = Result * Result;
/* call the setText method of Label lcdDisplay and send it the string
* that represents the value in Result
*/
displayField.setText(String.valueOf(Result));
Status = "FIRST"; //indicates this is the first time
//this button has been pressed
OperatorKey = true; //an operator button has been pressed
FunctionKey = true; //a function button has been pressed
}
} //end of the SqrButton method
/* This method is called whenever the square button is pressed */
void SqrRootButton()
{
DisplayError(" "); //clears the error message field
/* Declares a String called Display that will initialize to whatever
* is currently displayed in the lcdDisplay of the calculator
*/
String Display = displayField.getText();
/* if Status is not set to FIRST and the Display string does not
* hold the value "0"
*/
if ((Status != "FIRST") || (Display != "0"))
{
/* Creates a new Double object with the specific purpose of retaining
* the string currently on the lcdDisplay label, and then immediately
* converts that string into a double-precision real number and then
* gives that number to the variable Result.
*/
Result = (new Double(displayField.getText())).doubleValue();
/* Makes a call to the Math class method "sqrt", which produced the
* square root and stores the value in Result
*/
Result = Math.sqrt(Result);
/* call the setText method of Label lcdDisplay and send it the string
* that represents the value in Result
*/
displayField.setText(String.valueOf(Result));
Status = "FIRST"; //indicates this is the first time
//this button has been pressed
OperatorKey = true; //an operator button has been pressed
FunctionKey = true; //a function button has been pressed
}
} //end of the SqrRootButton method
/* This method is called whenever the OneOverXButton is pressed */
void OneOverXButton()
{
DisplayError(" "); //clears the error message field
/* Declares a String called Display that will initialize to whatever
* is currently displayed in the displayField of the calculator
*/
String Display = displayField.getText();
/* if Status is not set to FIRST and the Display string does not
* hold the value "0"
*/
if ((Status != "FIRST") || (Display != "0"))
{
/* Creates a new Double object with the specific purpose of retaining
* the string currently on the lcdDisplay label, and then immediately
* converts that string into a double-precision real number and then
* gives that number to the variable Result.
*/
Result = (new Double(displayField.getText())).doubleValue();
//divides one by the double Result
Result = 1 / Result;
/* call the setText method of Label lcdDisplay and send it the string
* that represents the value in Result
*/
displayField.setText(String.valueOf(Result));
Status = "FIRST"; //indicates that this is the first time
//this button has been pressed
OperatorKey = true; //an operator key has been pressed
FunctionKey = true; //a function key has been pressed
}
} //end of the OneOverXButton method
/* This method is called whenever one of the three memory buttons is pressed,
* accepting an integer representing the button pressed as an argument
*/
void MemoryButton(int i)
{
DisplayError(" "); //clears the error message field
/* Declares a String called Display that will initialize to whatever
* is currently displayed in the lcdDisplay of the calculator
*/
String Display = displayField.getText();
//depending on the value sent representing the buttons
switch (i)
{
/* if the M+ button is pressed, check if the Display string has the value
* "0." OR just "0", but along with the second condition check if double
* Mem holds the value zero
*/
case OpMPlus : if (((Display == "0.") || (Display == "0")) && (Mem == 0))
{
//clears the LabelMem label
LabelMem.setText(" ");
}
else
{
/* Creates a new double variable called temp, which accepts the
* double value of a new Double object retaining the string
* currently on the lcdDisplay label, and then immediately
* converts that string into a double-precision real number
*/
double temp = (new Double(displayField.getText())).doubleValue();
//set the Mem variable with that the sum of what's currently in
//Mem and the temp variable
Mem = Mem + temp;
/* calls the setText method of the Label LabelMem, sending
* it the character "M"
*/
LabelMem.setText("M");
}
break;
/* if the MR button is pressed, call the setText method of Label lcdDisplay,
* sending it the string that represents what the value of Mem is
*/
case OpMR : displayField.setText(String.valueOf(Mem));
break;
/* if the MC button is pressed, set the Mem variable to zero */
case OpMClear : Mem = 0;
//clears the LableMem field
LabelMem.setText(" ");
break;
}
Status = "FIRST"; //indicates that this is first time
//button has been pressed
OperatorKey = true; //an operator button has been pressed
//if the Mem variable has the value zero
if (Mem == 0)
{
LabelMem.setText(" "); //clear the LabelMem field
}
} //end of the MemoryButton method
}
void Clicked_Clear()
{
Counter = 0; //sets the counter to zero
Status = "FIRST"; //sets Status to FIRST
Operand = 0; //sets Operand to zero
Result = 0; //sets Result to zero
Operator = 0; //sets Operator integer to zero
DecimalFlag = false; //decimal button has not been
//pressed
SignFlag = false; //sign button has not been pressed
OperatorKey = false; //no operator button has been
//pressed
FunctionKey = false; //no function button has been
//pressed
/* calls the setText method of Label lcdDisplay and sends
* it the character "0"
*/
displayField.setText("0");
DisplayError(" "); //clears the error message field
}
/* This method is called whenever anything needs to be displayed
* in the error message field at the bottom of the calculator,
* accepting a String as an argument
*/
void DisplayError(String err_msg)
{
/* calls the setText method of the Label DisplError, sending
* whatever string it received initially
*/
errorMsg.setText(err_msg);
}
}//end of actionPerformed method
