So I am making a very basic cash register program currently for my college class. Basically every time I press a button it adds to a total, and when I press total it sums it all up. The the problem is that I can't seem to call the value from the variable into the total button. It always stays 0.0 even though I am making that variable have a value when I press the other events. I need to get past this point so I can check to see if the if statements are working properly.
The end result would be a register that I can always change its total by pressing a different combination of buttons. If I press one button, it will come up with a sum. So if I press button one once, it will only be 1.50 for example. But if I press it two times, it will be 3.0. I know I probably should use a counter for each event and get the product of that counter with the predetermined value that I am setting. But right now I can't seem to get past the problem with my total button event. Here is my code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class BobsBurgerPanel extends JPanel
{
private int test1 = 1;
private double totalResult;
private double total1, total2, total3, total4, total5, total6;
private JButton push1, push2, push3, push4, push5, push6, total;
private JTextField text;
private JLabel label;
public BobsBurgerPanel()
{
push1 = new JButton("Small Drink");
push2 = new JButton("Large Drink");
push3 = new JButton("Small Fry");
push4 = new JButton("Large Fry");
push5 = new JButton("Veggie Burger");
push6 = new JButton("Bison Burger");
total = new JButton("Total");
label = new JLabel(" Your total is: ");
// Lining the text up with the JTectfield. \t or \n do not work.
text = new JTextField(10);
total.addActionListener(new TempListener());
add(push1);
add(push2);
add(push3);
add(push4);
add(push5);
add(push6);
add(total);
add(label);
add(text);
setPreferredSize(new Dimension(400,300));
setBackground(Color.red);
}
private class TempListener implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
int counter1 = 0, counter2 = 0, counter3 = 0,
counter4 = 0, counter5 = 0, counter6 = 0, counter7 = 0;
double totalR;
if (event.getSource() == push1)
{
counter1++;
total1 = counter1 * 1.50;
}
if (event.getSource() == push2)
{
counter2++;
total2 = counter2 * 2.10;
}
if (event.getSource() == push3)
{
counter3++;
total3 = counter3 * 2.00;
}
if (event.getSource() == push4)
{
counter4++;
total4 = counter4 * 2.95;
}
if (event.getSource() == push5)
{
counter5++;
total5 = counter5 * 4.55;
}
if (event.getSource() == push6)
{
counter6++;
total6 = counter6 * 7.95;
}
if (event.getSource() == total)
totalResult =
(total1+total2+total3+total4+total5+total6);
text.setText(Double.toString(totalResult));
}
}
Any help or additional ideas would be great. Thanks for reading.
Your counter variables are declared local and therefore are 0 at every iteration. I recommend you declare them outside of your method since you need them to be incremented every time an action is performed.
Also, since your code can only be in one state at a time, you would benefit from else statements instead of just if.
Dude you've added listener only to your JButton total. So the actionPerformed method always and only gets through
if (event.getSource() == total)
totalResult =(total1+total2+total3+total4+total5+total6);
statement, because JButton total is the only source of click event. That's why you're getting 0 over and over again.
Related
I am trying to simulate a coin flipper using Java and window builder. I have a button called "Flip" when that button is pressed the coin image changes depending on which number the random generator I created generates.
I now am trying to figure out a way to display the number of times the coin lands a heads or a tails in their respective JTextFields. I was thinking of using a counter, but I am struggling with how to update that into the text field, so far it only puts in that I have flipped each coin once.
I am very new to programming so any advice or guidance is much appreciated.
// this button flips the coin
btnFlip = new JButton("Flip");
btnFlip.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
int headCounter = 0;
int tails = 0;
// this implements the random flip of the coin when the checkbox Run Multiple
// flips is unchecked
if (chckbxNewCheckBox.isSelected() == false) {
Random r = new Random();
int flipper = r.nextInt(2);
if (flipper == 1) {
lblImages.setIcon(new ImageIcon(FinalPrep.class.getResource("/finalPrep/heads.png")));
textFieldHeads.setText(String.valueOf(headCounter));
} else {
lblImages.setIcon(new ImageIcon(FinalPrep.class.getResource("/finalPrep/tails.png")));
textFieldTails.setText(String.valueOf(tails));
}
}
}
});
btnFlip.setFont(new Font("Tahoma", Font.PLAIN, 15));
panel_1.add(btnFlip);
You have to create something like 2 layers. One that contains the window itself along with the title (think of it like a receptor) then you have to create another "layer" that contains the buttons and the textfields. Something like this:
import javax.swing.*;
public class MyFrame extends JFrame {
private JPanel panel;
private JTextField textField;
private JButton button;
public MyFrame(){
panel = new JPanel(); //Step 1. Creation of a receptor
tfCount = new JTextField(10); //Step 2.
button = new JButton("Press Me"); //Creation of buttons & textfields.
panel.add(tfCount); //Step 3.
panel.add(button); //Add those graphics to the receptor
this.setContentPane(panel); //Step 4 Adjust the receptor to the object
this.setVisible(true);
this.setSize(400, 400);
this.setTitle("My 1st GUI!");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
(Sorry for the random example but you did not post any sample of code so I am trying to explain as best as I can)
Then you should put a "flag" depending of the number that was generated for example:
boolean flag = true; //Flag
int counter = 0; //The counter for the heads
int x; //The number you received from the generator
int counter_b; //The counter for the tails
if(x%2 == 0){ //If the number is even
flag = false; // You set down the flag
counter++; //And counter raises its value
}
else
counter_b++;
tfCount.setEditable(true); //This makes your textfield editable
tfCount.setText(String.valueOf(counter)); //And this prints the counter's value
Keep in mind that the counters for the tails and the heads are just examples for you to understand how to use "flags". I hope that I was able to help you because I am new too!! :)
I created a dialog box and have the user enter 5 colors in it from memory. That all completely works, there's just a slight aesthetic problem. Upon entering all 5 colors correctly, or getting one incorrect, it's suppose to wipe the contents within the dialog box and print a message "Sorry! Incorrect color" or "Congratulations". It prints the message, but the JTextField can still be seen somewhat behind the message (A left over portion/clipping).
I've tried using the hide() and remove() methods but they didn't seem to work (Or I'm using them incorrectly), I tried re-making a dialog box upon either but I couldn't seem to solve the issue still. What am I doing wrong/how can I make the JTextField disappear upon completion? Thank you in advance for any help!
Here's the portion where if the user enters a color incorrectly or gets them all correct (txtName is the JTextField):
if(count == 6)//User either finished or entered a color incorrectly
{
//Entered color incorrectly
if(incorrect == true)
{
txtName.setEnabled(false); //Doesn't work
homeScreen.remove(txtName); //Doesn't work
labelName.setText("Incorrect! Sorry - Wrong color.");
//txtName.removeActionListener(new MyButtonListener());
}
else//Correctly finished the game.
{
labelName.setText("Congratulations - your memory skills are perfect!");
//txtName.removeActionListener(new MyButtonListener());
homeScreen.remove(txtName);//Doesn't work
}
}
Here's my entire program (I can't get it format properly in the post):
package memorygame;
import java.util.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.FlowLayout;
public class MemoryGame
{
private JFrame homeScreen;
private JLabel labelName;
private JTextField txtName;
private JLabel correct;
Vector<String> name = new Vector();
private int count = 1;
private MyButtonListener listen1 = new MyButtonListener();
//Constructor - Method to be called when MemoryGame object called
public void MemoryGame ()
{
homeScreen = new JFrame();
homeScreen.setSize(400,200);
homeScreen.setTitle("Memory Game");
homeScreen.setDefaultCloseOperation(homeScreen.EXIT_ON_CLOSE);
homeScreen.setLayout(new FlowLayout());
labelName = new JLabel();
txtName = new JTextField(10);
createContents();
homeScreen.setVisible(true);
}//End Constructor
//Create components and add them to the window/dialog box
private void createContents()
{
labelName.setText("Enter the color " + count + ":");
System.out.println("The current count is: " + count);
homeScreen.add(labelName);
homeScreen.add(txtName);
txtName.addActionListener(new MyButtonListener());//Allows you to press enter to invoke action
}
//Upon user hitting enter
private class MyButtonListener implements ActionListener
{
public void actionPerformed (ActionEvent e)//When event occurs
{
Scanner in = new Scanner (System.in);//For program input
String answer = "";
//Make memColor an array for randomized colors
/*
Random r = new Random();
String[] memColors = new String[5];
String[] colors = {"red", "green", "blue", "yellow", "brown", "purple"};
for(int i =0; i < memColors.length; i++)
{
memColors[i] = colors[r.nextInt(6)];
}
*/
String memColor1 = "red";
String memColor2 = "black";
String memColor3 = "yellow";
String memColor4 = "green";
String memColor5 = "blue";
boolean incorrect = false;
//If answered incorrectly set count to 5(it'll be 6)
//And have a boolean for if count== 6 for congrats and failure
if(e.getSource() == txtName)
{
answer = txtName.getText();
System.out.println(answer);
}
else
{}
//Check if user entered Correct color, 1= Red, 2= Black, etc.
if(count == 1)
{
if(answer.equalsIgnoreCase(memColor1))
{
txtName.setText("");
}
else
{//Needs to be a custom message box
count = 5;
incorrect = true;
}
}
else if(count == 2)
{
if(answer.equalsIgnoreCase(memColor2))
{
txtName.setText("");
}
else
{
count = 5;
incorrect = true;
}
}
else if(count == 3)
{
if(answer.equalsIgnoreCase(memColor3))
{
txtName.setText("");
}
else
{
count = 5;
incorrect = true;
}
}
else if(count == 4)
{
if(answer.equalsIgnoreCase(memColor4))
{
txtName.setText("");
}
else
{
count = 5;
incorrect = true;
}
}
else if(count == 5)
{
if(answer.equalsIgnoreCase(memColor5))
{
txtName.setText("");
}
else
{
count = 5;
incorrect = true;
}
}
else
{
JOptionPane.showMessageDialog(null, "Something went wrong!");
}
count += 1;
//User has completed the game or entered a color incorrectly
if(count == 6)
{
if(incorrect == true) //Incorrect color
{
txtName.setEnabled(false);
homeScreen.remove(txtName);
labelName.setText("Incorrect! Sorry - Wrong color.");
//txtName.removeActionListener(new MyButtonListener());
}
else //Completed the game correctly
{
labelName.setText("Congratulations - your memory skills are perfect!");
//txtName.removeActionListener(new MyButtonListener());
homeScreen.remove(txtName);
}
}
else
{
labelName.setText("Enter the color " + count + ":");
}
}//End Listener
}//End Button class
public static void main(String[] args) {
//Show message box
//Randomize colors
JOptionPane.showMessageDialog(null, "How good is your memory?\nTry to memorize this color sequence:\n\n red black yellow green blue");
MemoryGame mem = new MemoryGame();
mem.MemoryGame();
}//End Main
}// End Class
Use txtName.setVisible(false); instead of homeScreen.remove(txtName);
Basically, if you want to call remove, you will need to revalidate and repaint container...
You'll also want to ensure that your UI is create within the context of the Event Dispatching Thread, see Initial Threads for more details
Change the code
homeScreen.remove(txtName);
to
homeScreen.remove(txtName);
homeScreen.revalidate();
homeScreen.repaint();
The reason why remove() does not imply revalidate() + repaint() is that remove() is not atomic. The caller might want to perform multiple updates, a sequence of several add() and remove() calls. revalidate() basically "completes" your "UI update transaction", repaint() "pushes it to the screen".
As a side note, your code will be easier to understand and maintain, if you perform a small tiny improvements on variable names. What's homeScreen? And why is it called labelName - what name? And what's txtName - the name of what text? count of what, icecreams?
I suggest the following improvements:
incorrect -> isIncorrect (also change if (incorrect == true) to if (isIncorrect)
homeScreen -> mainFrame or just frame (as you only have one frame)
labelName -> infoLabel or just label (as you only have one label - and remove JLabel correct, it's unused)
txtName -> answerTextField
count -> answerCount
Remove variable listen1, it's not used.
Plus, if you look at the code that does if (count == 1) and the following four if clauses, they are all identical except for the number. A perfect situation for an array. You can convert the variables memColor* to an array String[] memColor. Or maybe that's what the Vector was for. You might instead want to use ArrayList, nobody uses Vector these days in such situations.
So I'm making a Java Calculator and walking into some errors upon clicking the function buttons (it compiles perfectly fine though).
The error on the 1st line in my CMD was a NumberFormat Exception. After some searching I figured out that somewhere in my code I was trying to get a double out of an empty string (basically what I'm trying to do is parse a double from the label text). I'm guessing it's this part:
// if statement that puts the labels text into the first or second number
if(firstNumber)
{
number1 = Double.parseDouble(label.getText().trim());
} else {
number2 = Double.parseDouble(label.getText().trim());
}
Basically the problems are when i push the / * + or - button i get a NumberFormatExeption: For input string "/" etc.
I can't quite figure out how i have to fix this error (I'm still (somewhat) a beginner in Java).
Further down the line of errors (there were quite alot) were a whole lot of errors I didn't understand such as EventDispatchThread, EventQueue and many others. I couldn't find an explanation on my level of experience either so I'm asking for help here.
The numeric buttons all work fine.
At run: [http://gyazo.com/71cb4dde449ccf7ece44017388a71a0f]
Putting in numbers: [http://gyazo.com/5c7ab6c54ac6da180845c66866d66f8f]
All other buttons give errors in my CMD.
Here's my code (the spacing might be messed up in some parts):
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
// import for Nimbus look
import javax.swing.UIManager.*;
public class Calculator extends JFrame implements ActionListener
{
private JPanel bottom = new JPanel(); private JPanel top = new JPanel();
private JLabel label = new JLabel(" ");
private JButton[] buttons = new JButton[16];
// booleans for calculator functions
boolean add = false, substract = false, devide = false, multiply = false, firstNumber = true;
// numbers that will be calculated
double number1, number2;
public Calculator()
{
setLayout(new BoxLayout(getContentPane(), BoxLayout.PAGE_AXIS));
// bottom panel
bottom.setPreferredSize(new Dimension(100,100));
bottom.setLayout(new BorderLayout());
//add bottom panel to frame
add(bottom);
// top panel
top.setPreferredSize(new Dimension(300,400));
top.setLayout(new GridLayout(4,4,3,3));
top.setBackground(Color.BLACK);
//dont add top panel to frame: you want top to be on bottom
// add top panel to bottom panel
bottom.add(top);
// label
label.setFont(new Font("Courier", Font.PLAIN, 20));
label.setBackground(Color.BLACK);
label.setForeground(Color.WHITE);
label.setHorizontalAlignment(SwingConstants.RIGHT); // text is right-aligned
label.setOpaque(true);
// add the label to the bottom panel
bottom.add(label, BorderLayout.NORTH);
// creating buttons
for(int i = 0; i < buttons.length; i++)
{
buttons[i] = new JButton("789/456*123+c0=-".substring(i, i+1));
buttons[i].addActionListener(this);
// add them to the top panel
top.add(buttons[i]);
}
// Nimbus look
try {
for (LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (Exception e) {
// If Nimbus is not available, you can set the GUI to another look and feel.
//set to default somehow o.o
}
// frame setters
setTitle("Calculator");
setSize(400,400);
setVisible(true);
setResizable(false);
setDefaultCloseOperation(EXIT_ON_CLOSE);
}
public void Clear()
{
label.setText(" ");
}
#Override
public void actionPerformed(ActionEvent e)
{
//if's for all function buttons
if(e.getSource() == buttons[3])
{
// devide
devide = true;
substract = false;
add = false;
multiply = false;
firstNumber = false;
Clear();
label.setText("/");
}
if(e.getSource() == buttons[7])
{
// multiply
multiply = true;
substract = false;
devide = false;
add = false;
firstNumber = false;
Clear();
label.setText("*");
}
if(e.getSource() == buttons[11])
{
// add
add = true;
substract = false;
devide = false;
multiply = false;
firstNumber = false;
Clear();
label.setText("+");
}
if(e.getSource() == buttons[12])
{
// clear
label.setText("0");
number1 = 0.00;
number2 = 0.00;
add = false;
substract = false;
devide = false;
multiply = false;
firstNumber = true;
Clear();
}
if(e.getSource() == buttons[15])
{
// substract
substract = true;
add = false;
devide = false;
multiply = false;
firstNumber = false;
Clear();
label.setText("-");
}
// for loops that add the numbers on the buttons to the label
for(int i = 0; i < 3; i++)
{
if(e.getSource() == buttons[i])
{
if(label.getText() == "0")
{
label.setText("");
label.setText(label.getText() + buttons[i].getText());
} else {
label.setText(label.getText() + buttons[i].getText());
}
}
}
for(int i = 4; i < 7; i++)
{
if(e.getSource() == buttons[i])
{
if(label.getText() == "0")
{
label.setText("");
label.setText(label.getText() + buttons[i].getText());
} else {
label.setText(label.getText() + buttons[i].getText());
}
}
}
for(int i = 8; i < 11; i++)
{
if(e.getSource() == buttons[i])
{
if(label.getText() == "0")
{
label.setText("");
label.setText(label.getText() + buttons[i].getText());
} else {
label.setText(label.getText() + buttons[i].getText());
}
}
}
for(int i = 13; i < 14; i++)
{
if(e.getSource() == buttons[i])
{
if(label.getText() == "0")
{
label.setText("");
label.setText(label.getText() + buttons[i].getText());
} else {
label.setText(label.getText() + buttons[i].getText());
}
}
}
// if statement that puts the labels text into the first or second number
if(firstNumber)
{
number1 = Double.parseDouble(label.getText().trim());
} else {
number2 = Double.parseDouble(label.getText().trim());
}
// calculation
if(e.getSource() == buttons[14])
{
// calculate
if(devide){number1 = ((double)(number1) / (double)(number2)); }
if(multiply){number1 = ((double)(number1) * (double)(number2)); }
if(add){number1 = ((double)(number1) + (double)(number2)); }
if(substract){number1 = ((double)(number1) - (double)(number2)); }
label.setText(Double.toString(number1));
}
}
public static void main(String[] args)
{
new Calculator();
}
}
Lastly, the calculations made by the calculator are incorrect. I also can't wrap my head around what's causing that. Please bear in mind that I'm a beginner at Java and this is my first question on stackoverflow. Thanks in advance for helping me, whoever will :)
UPDATE: i fixed the errors by putting my code as follows:
if(e.getSource() == buttons[15])
{
// substract
substract = true;
add = false;
devide = false;
multiply = false;
firstNumber = false;
isNumberKey = false;
if(isNumberKey)
{
if(firstNumber)
{
label.setText(label.getText().replace("/",""));
label.setText(label.getText().replace("*",""));
label.setText(label.getText().replace("+",""));
label.setText(label.getText().replace("-",""));
number1 = Double.parseDouble(label.getText().trim());
} else {
label.setText(label.getText().replace("/",""));
label.setText(label.getText().replace("*",""));
label.setText(label.getText().replace("+",""));
label.setText(label.getText().replace("-",""));
number2 = Double.parseDouble(label.getText().trim());
}
}
Clear();
label.setText("-");
}
All i need to do now is fix the calculations...
Thanks for the help everyone!
Cannot delve totaly into your logic there, but here's some hints:
First, you don't have to guess where the error is. In case of uncaught exception like here, thread that produced it will print it's stack trace to console. It looks like this:
Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: "/"
at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1222)
at java.lang.Double.parseDouble(Double.java:510)
at mypackage.Calculator.actionPerformed(Calculator.java:229)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
at java.awt.Component.processMouseEvent(Component.java:6297)
From here you see that exception happened in thread named AWT-EventQueue-0, which is swing's standard event dispatching thread (all GUI applications handles events in single thread). Another thing you search in stack trace is to find what line in your code thrown it. Here it's the line:
at mypackage.Calculator.actionPerformed(Calculator.java:229)
In source, it is line:
number2 = Double.parseDouble(label.getText().trim());
, so you guessed right. What you can do is add another boolean there which will be set only if number button is hit, and then change that part of code to something like:
if( isNumber){
if(firstNumber)
{
number1 = Double.parseDouble(label.getText().trim());
} else {
number2 = Double.parseDouble(label.getText().trim());
}
}
Apart from that, instead of using multiple boolean flags for operation, use Java enum type
enum Operation {devide, substract, add, multiply};
your code will be more readable and "java" styled.
Good starting point, just go ahead!
Disclaimer: I'm on my phone so it's hard to parse your code; with that being said, I believe your number format exception deals with what is stored in the label text.
From the looks of it if you hit an operator button (like multiply), the labelText will be "*", then if you hit number button (like 5), the labelText will be "*5". Finally, if you hit the enter button now to go calculate the answer, Double.parseDouble(label.getText().trim()), will be ran which will throw the NumberFormatException. Using the operation flags, it looks like you don't even need to store the operator (unless you're trying to display the operator to the user); in that case you need to strip the operator from the string before trying the parse the double.
label.setText(label.getText().replace("/",""));
label.setText(label.getText().replace("*",""));
label.setText(label.getText().replace("+",""));
label.setText(label.getText().replace("-",""));
As for the other exceptions, in eclipse you can set a breakpoint to halt the program when a specific exception occurs. This will help you debug your code further.
more info on that here
I am having issues trying to get this program to run, the applet loads, but when I enter a number and click ok, nothing seems to happen... I am not sure if I have an issue with the array or where my issue might lie.
I can't seem to figure out what exactly I am doing wrong.
import java.awt.*;
import java.applet.*;
import java.awt.event.*;
import javax.swing.JOptionPane;
public class LargestApplet extends Applet implements ActionListener {
private static final long serialVersionUID = 1L;
int number =0;
double highNumber=-1;
double lowNumber=-1;
// Create components for applet
Label numberLabel = new Label("Enter a number:");
TextField numberField = new TextField(5);
Button okButton = new Button("OK");
Button cancelButton = new Button("Cancel");
Label highNumberOutputLabel = new Label("The Highest number is: 0 ");
public void init() {
add(numberLabel);
add(numberField);
numberField.requestFocus();
add(okButton);
add(cancelButton);
add(highNumberOutputLabel);
setSize(400, 500); // Sets the size of the applet window
}
public void actionPerformed(ActionEvent e) {
int number = 0, highNumber = -1;
if (numberField.getText().length() == 0) {
numberField.requestFocus();
JOptionPane.showMessageDialog(null,
"Number Cannot blank", "D A T A E R R O R",
JOptionPane.ERROR_MESSAGE);
return;
}
try {
number = Integer.parseInt(numberField.getText());
} catch (NumberFormatException ex) {
numberField.requestFocus();
JOptionPane.showMessageDialog(null, "Number is invalid",
"D A T A E R R O R", JOptionPane.ERROR_MESSAGE);
return;
}
if (number < 0 || number > 10) {
numberField.requestFocus();
JOptionPane.showMessageDialog(null,
"Number must be between 0 and 10",
"D A T A E R R O R", JOptionPane.ERROR_MESSAGE);
return;
}
// Determine highest number
Integer [] numberAr = {number};
for(int i = 0; i < numberAr.length; i++)
{
number += numberAr[i];
if (numberAr[i] < lowNumber)
lowNumber = numberAr[i];
else if (numberAr[i] > highNumber)
highNumber = numberAr[i];
}
// Display the results
highNumberOutputLabel.setText("The Highest Number is: "
+ (highNumber));
}
}
You aren't adding the ActionListener to your buttons, and so pushing a button will have no effect. Fix that by calling addActionListener(this) on the relevant Button. Just having your GUI class extend ActionListener (which is also not a good idea in general) does not magically give buttons the action listener code, and pressing a button will have no effect if you don't first give it code to have a behavior.
More importantly, you should be coding with Swing (JApplet, JButton) not AWT. While Swing is admittedly out of date, AWT is prehistoric in comparison.
And most importantly for us, you should not be posting NullPointerExceptions with your question if you code isn't throwing any.
I need to make the following exceptions: NoSuchRowException if the row is not between 1 and 3, IllegalSticksException if the number of sticks taken is not between 1 and 3, and NotEnoughSticksException if the number of sticks taken is between 1 and 3, but more than the number of sticks remaining in that row. My issue is I really don't understand the syntax. If someone could help me get started with one exception, I think I can figure the others out.
So far I have the main class:
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package nimapp;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
/**
*
* #author jrsullins
*/
public class NimApp extends JFrame implements ActionListener {
private static final int ROWS = 3;
private JTextField[] gameFields; // Where sticks for each row shown
private JTextField rowField; // Where player enters row to select
private JTextField sticksField; // Where player enters sticks to take
private JButton playButton; // Pressed to take sticks
private JButton AIButton; // Pressed to make AI's move
private NimGame nim;
public NimApp() {
// Build the fields for the game play
rowField = new JTextField(5);
sticksField = new JTextField(5);
playButton = new JButton("PLAYER");
AIButton = new JButton("COMPUTER");
playButton.addActionListener(this);
AIButton.addActionListener(this);
AIButton.setEnabled(false);
// Create the layout
JPanel mainPanel = new JPanel(new BorderLayout());
getContentPane().add(mainPanel);
JPanel sticksPanel = new JPanel(new GridLayout(3, 1));
mainPanel.add(sticksPanel, BorderLayout.EAST);
JPanel playPanel = new JPanel(new GridLayout(3, 2));
mainPanel.add(playPanel, BorderLayout.CENTER);
// Add the fields to the play panel
playPanel.add(new JLabel("Row: ", JLabel.RIGHT));
playPanel.add(rowField);
playPanel.add(new JLabel("Sticks: ", JLabel.RIGHT));
playPanel.add(sticksField);
playPanel.add(playButton);
playPanel.add(AIButton);
// Build the array of textfields to display the sticks
gameFields = new JTextField[ROWS];
for (int i = 0; i < ROWS; i++) {
gameFields[i] = new JTextField(10);
gameFields[i].setEditable(false);
sticksPanel.add(gameFields[i]);
}
setSize(350, 150);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
nim = new NimGame(new int[]{3, 5, 7});
draw();
}
// Utility function to redraw game
private void draw() {
for (int row = 0; row < ROWS; row++) {
String sticks = "";
for (int j = 0; j < nim.getRow(row); j++) {
sticks += "| ";
}
gameFields[row].setText(sticks);
}
rowField.setText("");
sticksField.setText("");
}
public void actionPerformed(ActionEvent e) {
// Player move
if (e.getSource() == playButton) {
// Get the row and number of sticks to take
int row = Integer.parseInt(rowField.getText())-1;
int sticks = Integer.parseInt(sticksField.getText());
// Play that move
nim.play(row, sticks);
// Redisplay the board and enable the AI button
draw();
playButton.setEnabled(false);
AIButton.setEnabled(true);
// Determine whether the game is over
if (nim.isOver()) {
JOptionPane.showMessageDialog(null, "You win!");
playButton.setEnabled(false);
}
}
// Computer move
if (e.getSource() == AIButton) {
// Determine computer move
nim.AIMove();
// Redraw board
draw();
AIButton.setEnabled(false);
playButton.setEnabled(true);
// Is the game over?
if (nim.isOver()) {
JOptionPane.showMessageDialog(null, "You win!");
playButton.setEnabled(false);
}
}
}
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
NimApp a = new NimApp();
}
}
The support class:
package nimapp;
import java.util.Random;
import javax.swing.JOptionPane;
import java.io.*;
import java.lang.*;
public class NimGame {
int x = 1;
int[] Sticks; //creating an array of sticks
int totalSticks = 0;
public NimGame(int[] initialSticks){
Sticks = initialSticks;}
public int getRow(int r){
return Sticks[r];}
public void play(int r, int s) throws IllegalSticksException {
try {
Sticks[r]=Sticks[r]-s;
if(s < 0 || s > 3)
throw new IllegalSticksException();
} catch (IllegalSticksException ex){
JOptionPane.showMessageDialog(null, "Not a valid row!");
} catch (IndexOutOfBoundsException e){
JOptionPane.showMessageDialog(null, "Too Many Sticks!");
}
}
public boolean isOver(){
int theTotal = 0;
for (int i = 0; i< Sticks.length; i++){
theTotal = Sticks[i];
System.out.println(Sticks[i]);
System.out.println(theTotal);
}
totalSticks = theTotal;
if (totalSticks <= 0){
return true;
}
else return false;
}
public void AIMove(){
Random randomInt = new Random ();
boolean tryRemove = true;
while(tryRemove && totalSticks >= 1){
int RandomRow = randomInt.nextInt(3);
if(Sticks[RandomRow] <= 0)//the computer can't remove from this row
continue;
//the max number to remove from row
int size = 3;
if( Sticks[RandomRow] < 3)//this row have least that 3 cards
size = Sticks[RandomRow];//make the max number to remove from the row be the number of cards on the row
int RandomDiscard = randomInt.nextInt(size) + 1;
Sticks[RandomRow] = Sticks[RandomRow] - RandomDiscard;
//I don't know if this is needed, but since we remove a RandomDiscard amount lest decrease the totalSticks
totalSticks = totalSticks - RandomDiscard;
//exit loop
tryRemove = false;
}
if(totalSticks <= 1){
int RandomRow = 0;
Sticks[RandomRow] = Sticks[RandomRow]-1;
isOver();
}
}
}
My issue is I really don't understand the syntax.
There is nothing wrong with the syntax as you have written it.
The problem is that you are catching the exception at the wrong place. You are (apparently) intending play to propagate the IllegalSticksException to its caller. But that won't happen because you are catching it within the play method.
There are two possible fixes depending on what you actually intent to happen.
You could remove the throws IllegalSticksException from the play signature.
You could remove the catch (IllegalSticksException ex){ ... } in play and catch/handle the exception at an outer level.