Develop Reference

Looping letter input

I'm making a hangman game for school and I've run into a problem that I simply can't solve, maybe I'm overthinking, maybe I'm not. Anyways, I need to let the user input a letter, and if that letter is in the word used for the game (pikachu. I know, stupid choice but it's pretty basic and easy so I used that) then the letter is revealed, the problem is that after inputting a letter, the user can't guess any more letters. I need a way to loop through the letter input and revealing so that I can actually play the game.
I'm sorry if the solution is so simple but I just can't figure out what needs to change in my code in order to fix my problem because I'm very new to java.
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JPanel;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.*;
import java.awt.event.KeyListener;
import javax.swing.*;
public class PanDisp extends JPanel {
JLabel lblOutput;
JLabel lblGuess;
JButton btnUpdateLabel;
Image imgPkmn;
FraImg fraImg;
String sSecret;
public PanDisp() {//Constructor
KeyInput keyInput = new KeyInput();
KeyInput.LabelChangeListener labelChange = keyInput.new LabelChangeListener();
sSecret = "*******";
lblGuess = new JLabel("Type will go here");
lblOutput = new JLabel(sSecret);
btnUpdateLabel = new JButton("Enter");
add(lblOutput);
add(btnUpdateLabel);
addKeyListener(new KeyInput());
setFocusable(true);
btnUpdateLabel.addActionListener(labelChange);
fraImg = new FraImg(imgPkmn);
}
public void GameOver() {
}
class KeyInput implements KeyListener {
String sInput;
String sWord = "pikachu";
String sSecret = "*******";
char chInput;
#Override
public void keyTyped(KeyEvent e) {
}
#Override
public void keyPressed(KeyEvent e) {
chInput = (char) e.getKeyChar();
sInput = String.valueOf(chInput);
lblOutput.setText(sInput);
}
#Override
public void keyReleased(KeyEvent e) {
}
class LabelChangeListener implements ActionListener {
char cWord;
int nCorrect, nIncorrect, nNum;
public void actionPerformed(ActionEvent event) {
if (sWord.contains(sInput)) {
for (int i = 0; i < sWord.length(); i++) {
sSecret.replace(sSecret.charAt(i), sWord.charAt(i));
}
nCorrect += 1;
}
else {
nIncorrect += 1;
if (nIncorrect == 7) {
GameOver();
}
}
}
}
}
}

Your problem is that your mindset is off and has to be changed. Don't think "loop", and in fact get "loop" out of the equation. You're programming in an event-driven programming environment, and the loop you're thinking of belongs in the linear console programming environment. Instead think "state of object" and "behavioral changes to state changes", and you'll move much further in this quest. So change the state of your class -- number of guesses, number of correct guesses, and then change the response to the user's input based on this state
For instance, if you wanted to create a console program that allowed a user to enter 5 Strings, and then displayed those Strings back to the user, it would be pretty straight forward, in that you'd create your String array, and then use a for loop to prompt the user 5 times to enter text, grabbing each entered String within the loop. Here "loops" like the one you're requesting work.
Linear Console Program
import java.util.Scanner;
public class Enter5Numbers1 {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println("Please enter 5 sentences:");
String[] sentences = new String[5];
for (int i = 0; i < sentences.length; i++) {
System.out.printf("Enter sentence #%d: ", (i + 1));
sentences[i] = scanner.nextLine();
}
System.out.println("You entered the following sentences:");
for (String sentence : sentences) {
System.out.println(sentence);
}
scanner.close();
}
}
If on the other hand you wanted to create a GUI that did something similar, that prompted the user for 5 Strings and accepted those Strings into an array, you couldn't use the same type of for loop. Instead you would need to give your class an int String counter, perhaps called enteredSentenceCount, and in a JButton's ActionListener (or Action -- which is something very similar), you would accept an entered String (perhaps typed into a JTextField called entryField), only if the enteredSentenceCount is less than 5, less than the maximum number of Strings allowed. You would of course increment the enteredSentenceCount variable each time a String is entered. And this combination of increase a counter variable and checking its value will need to substutite for the concept of a "loop". So here the "state" of the class is held in the enteredSentenceCount, and the behavioral change we want is to alter what the button's Action does depending on the enteredSentenceCount's value -- if less than 5, accept a String, and if it is equal to or greater than 5, display the entered Strings.
Event Driven GUI Program
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import javax.swing.*;
public class Enter5Numbers2 extends JPanel {
private static final int MAX_SENTENCE_COUNT = 5; // number of Strings to enter
private static final String PROMPT_TEMPLATE = "Please enter sentence number %d:";
private String[] sentences = new String[MAX_SENTENCE_COUNT]; // array to hold entered Strings
private int enteredSentenceCount = 0; // count of number of Strings entered
private JTextField entryField = new JTextField(20); // field to accept text input frm user.
// JLabel to display prompts to user:
private JLabel promptLabel = new JLabel(String.format(PROMPT_TEMPLATE, (enteredSentenceCount + 1)));
public Enter5Numbers2() {
// create GUI
// First create Action / ActionListener for button
EntryAction entryAction = new EntryAction("Enter");
JButton entryButton = new JButton(entryAction); // pass it into the button
entryField.setAction(entryAction); // but give it also to JTextField so that the enter key will trigger it
// JPanel to accept user data entry
JPanel entryPanel = new JPanel(new FlowLayout(FlowLayout.LEFT, 0, 0));
entryPanel.add(entryField);
entryPanel.add(entryButton);
// allow main JPanel to display prompt
setBorder(BorderFactory.createTitledBorder("Please Enter 5 Sentences"));
setLayout(new GridLayout(2, 1));
add(promptLabel);
add(entryPanel);
}
// Action class, similar to an ActionListener
private class EntryAction extends AbstractAction {
public EntryAction(String name) {
super(name);
putValue(MNEMONIC_KEY, (int) name.charAt(0));
}
#Override
public void actionPerformed(ActionEvent e) {
// check that we haven't entered more than the max number of sentences
if (enteredSentenceCount < MAX_SENTENCE_COUNT) {
// if OK, get the entered text
String sentence = entryField.getText();
// put it in our array
sentences[enteredSentenceCount] = sentence;
entryField.setText(""); // clear the text field
entryField.requestFocusInWindow(); // set the cursor back into the textfield
enteredSentenceCount++; // increment our entered sentence count variable
promptLabel.setText(String.format(PROMPT_TEMPLATE, (enteredSentenceCount + 1))); // change prompt
}
// if the number of sentences added equals the number we want, display it
if (enteredSentenceCount == MAX_SENTENCE_COUNT) {
JTextArea textArea = new JTextArea(6, 30);
for (String sentence : sentences) {
textArea.append(sentence + "\n");
}
JScrollPane scrollPane = new JScrollPane(textArea);
JOptionPane.showMessageDialog(Enter5Numbers2.this, scrollPane, "Five Sentences Entered",
JOptionPane.PLAIN_MESSAGE);
}
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
JFrame frame = new JFrame("Enter 5 Numbers");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.add(new Enter5Numbers2());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
});
}
}

JButton stays pressed after a JOptionPane is displayed

Ok, I am sorry I am repeating questions that have already been asked but I have searched and searched and searched and nobody's answers seemed to have helped me... I tried the following questions:
JButton "stay pressed" after click in Java Applet
JButton stays pressed when focus stolen by JOptionPane
(I apologize if I'm just being dumb.. it is hard to relate to my code)
I have tried everything: using another thread to handle all the stuff, changing the JFrame to a JDialog as apparently they are "modal" so it would work independently. But that didn't seem to work either. I am stuck now so I am using my last resource (asking Stack Overflow).
What I am trying to do is get the user to enter some numbers in a textfield (4,2,7) then they press a JButton "Calculate Mean" and it finds the mean of the numbers and displays it in a JOptionPane message. When the user closes the JOptionPane dialog box they should be able to edit the numbers and do it again but the "Calculate Mean" button stays pressed and the user can't do anything but close the window. Even pressing the Tab key doesn't change anything. Does anyone know why this is? My code is down below:
PLEASE FORGIVE ME IF MY CODE IS HARD TO READ! I spent a very long time trying to indent it all correctly and I also tried to make it as short as possible by taking out any bits unrelated to the question. I was unsure which bits to take out so there still might be some unnecessary bits...
I am sorry for my messy code but this is the code:
package MathsProgram_II;
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.Arrays;
public class Mean implements Runnable {
JFrame meanFrame = new JFrame(); //I tried changing this to dialog
JPanel meanPanel = new JPanel(new GridBagLayout());
JLabel enterNums = new JLabel("Enter Numbers: ");
JTextField txtNums = new JTextField(20);
JButton calculate = new JButton("Calculate Mean");
boolean valid = true;
double answer = 0;
ButtonListener bl = new ButtonListener();
public synchronized double[] getArray() {
String nums = txtNums.getText();
String[] numsArray = nums.split(",");
double[] doubleArray = new double[numsArray.length];
if (nums.isEmpty() == true) {
JOptionPane.showMessageDialog(meanFrame, "You did not enter anything!",
"Fail", JOptionPane.ERROR_MESSAGE);
valid = false;
calculate.setEnabled(false);
} else {
for (int i = 0; i < numsArray.length; i++) {
try {
doubleArray[i] = Double.parseDouble(numsArray[i]);
} catch (NumberFormatException nfe) {
JOptionPane.showMessageDialog(meanFrame, "Error getting numbers!",
"Error", JOptionPane.ERROR_MESSAGE);
valid = false;
}
}
}
return doubleArray;
}
public synchronized void calculateMean() {
ArrayList<Double> numbersList = new ArrayList<Double>(20);
double[] theNumbers = getArray();
double tempAnswer = 0;
if (valid == true) {
int length = theNumbers.length;
for (int i = 0; i < theNumbers.length; i++) {
numbersList.add(theNumbers[i]);
}
for (int i = 0; i < length; i++) {
double y = numbersList.get(i);
tempAnswer = tempAnswer + y;
}
this.answer = tempAnswer / length;
//I ALSO TRIED DOING THIS:
txtNums.requestFocus();
calculate.setEnabled(false);
showMean();
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
}
}
}
public void showMean() {
JOptionPane.showMessageDialog(meanFrame, "The Mean: " + answer, "The Mean of Your Numbers", JOptionPane.INFORMATION_MESSAGE);
}
private class ButtonListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == calculate) {
meanFrame.remove(meanPanel);
meanFrame.setVisible(true);
calculateMean();
}
}
}
}

Don't remove the panel from your mainframe.
Don't use "synchronized" on your "calculateMean()" method. The code is executed on the Event Dispatch Thread (EDT) so it will be single threaded.
Don't use a Thread.sleep() on the EDT. This will prevent the GUI from repainting itself.

Program freezing(not responding) after button click no a Java app

Ok so I'm building to show students how a loop goes through an array, I have added 2 images to help explain and the code, the first is the result I get after I click go then it freezes . The Second image is what I'd like it to do after you put in the values of 1 in start, 15 in stop, 3 in step and click the Go Button. And then to be cleared on the click of Clear button. I think they probably related. Can anyone see the problem? Thanks in advanced!
import java.awt.*;
import java.awt.event.*;
import java.awt.Color;
import javax.swing.JOptionPane;
public class Checkerboard extends Frame implements ActionListener
{
int[] blocksTextField = new int[15];
Panel blocksPanel = new Panel();
TextArea blocksDisplay[] = new TextArea[16];
TextField start = new TextField (3);
TextField stop = new TextField (3);
TextField step = new TextField (3);
//Colors
Color Red = new Color(255, 90, 90);
Color Green = new Color(140, 215, 40);
Color white = new Color(255,255,255);
//textField ints
int inputStart;
int inputStop;
int inputStep;
//Lables
Label custStartLabel = new Label ("Start : ");
Label custStopLabel = new Label ("Stop : ");
Label custStepLabel = new Label ("Step : ");
//Buttons
Button goButton = new Button("Go");
Button clearButton = new Button("Clear");
//panel for input textFields and lables
Panel textInputPanel = new Panel();
//Panel for buttons
Panel buttonPanel = new Panel();
public Checkerboard()
{//constructor method
//set the 3 input textFields to 0
inputStart = 0;
inputStop = 0;
inputStep = 0;
//set Layouts for frame and three panels
this.setLayout(new BorderLayout());
//grid layout (row,col,horgap,vertgap)
blocksPanel.setLayout(new GridLayout(4,4,10,10));
textInputPanel.setLayout(new GridLayout(2,3,20,10));
buttonPanel.setLayout(new FlowLayout());
//setEditable()
//setText()
//add components to blocks panel
for (int i = 0; i<16; i++)
{
blocksDisplay[i] = new TextArea(null,3,5,3);
if(i<6)
blocksDisplay[i].setText(" " +i);
else
blocksDisplay[i].setText(" " +i);
blocksDisplay[i].setEditable(false);
// blocksDisplay[i].setBackground(Red);
blocksPanel.add(blocksDisplay[i]);
}//end for
//add componets to panels
//add text fields
textInputPanel.add(start);
textInputPanel.add(stop);
textInputPanel.add(step);
//add lables
textInputPanel.add(custStartLabel);
textInputPanel.add(custStopLabel);
textInputPanel.add(custStepLabel);
//add button to panel
buttonPanel.add(goButton);
buttonPanel.add(clearButton);
//ADD ACTION LISTENRS TO BUTTONS (!IMPORTANT)
goButton.addActionListener(this);
clearButton.addActionListener(this);
add(blocksPanel, BorderLayout.NORTH);
add(textInputPanel, BorderLayout.CENTER);
add(buttonPanel, BorderLayout.SOUTH);
//overridding the windowcClosing() method will allow the user to clisk the Close button
addWindowListener(
new WindowAdapter()
{
public void windowCloseing(WindowEvent e)
{
System.exit(0);
}
}
);
}//end of constructor method
public void actionPerformed(ActionEvent e)
{
//if & else if to see what button clicked and pull user input
if(e.getSource() == goButton) //if go clicked ...
{
System.out.println("go clicked");
try{
String inputStart = start.getText();
int varStart = Integer.parseInt(inputStart);
if (varStart<=0 || varStart>=15 )throw new NumberFormatException();
System.out.println("start = " + varStart);
// roomDisplay[available].setBackground(lightRed);
String inputStop = stop.getText();
int varStop = Integer.parseInt(inputStop);
if (varStop<=0 || varStart>=15 )throw new NumberFormatException();
System.out.println("stop = " + varStop);
String inputStep = step.getText();
int varStep = Integer.parseInt(inputStep);
if (varStep<=0 || varStep>=15 )throw new NumberFormatException();
System.out.println("step = " + varStep);
for (int i = varStart; i<varStop; varStep++)//ADD WHILE LOOP
{
blocksDisplay[i].setBackground(Red);
blocksDisplay[i].setText(" " +i);
}
}
catch (NumberFormatException ex)
{
JOptionPane.showMessageDialog(null, "You must enter a Start, Stop and Step value greater than 0 and less than 15",
"Error",JOptionPane.ERROR_MESSAGE);
}
}
else if(e.getSource() == clearButton ) //else if clear clicked ...
{
System.out.println("clear clicked");
}
//int available = room.bookRoom(smoking.getState());
//if (available > 0)//Rooms is available
}//end action performed method
public static void main(String[]args)
{
Checkerboard frame = new Checkerboard ();
frame.setBounds(50, 100, 300, 410);//changed size to make text feilds full charater size
frame.setTitle("Checkerboarder Array");
frame.setVisible(true);
}//end of main method
}

The problem is your loop: your loop variable name is i but you change the varStep variable instead of i so basically the loop variable never changes and thus the exit condition will never be true.
I believe you want to step i with varStep, so change your loop to:
for (int i = varStart; i<varStop; i += varStep)
// stuff inside loop

Take a look at this loop.
for (int i = varStart; i<varStop; varStep++)//ADD WHILE LOOP
{
blocksDisplay[i].setBackground(Red);
blocksDisplay[i].setText(" " +i);
}
It ends when i >= varStop, but neither i nor varStop change as a consequence of its execution, so it can never stop. You only increment varStep.
I think you want to increment i by varStep on each iteration instead, i.e. i += varStep

You use varStep++ in your for loop. I think you meant to do i+varStep.
The application freezes because you're never increasing i, resulting in an endless loop.

if else -if unexpected Message

I have a swing application that involves a Container, a JButton, a JPanel, a JTextArea and an array. The array of String objects and contains 5 elements.
I want to return all elements in the array by a method and compare each of them with the element entered by end user in the text area, after pressing a JButton.
If they are same a JOptionPane message displaying the matched element should appear. If they are different a JoptionPane should show a message saying Number Entered is not found in myArray else, a message saying please Enter something" should appear
The problem I face is that when the end user enters a valid number a JOptionPane message saying: Number Entered is not found in myArray appear many times, e.g. when entering 4, a JoptionPane message saying
Number Entered is not found in myArray appear 3 times.
How do I prevent this message if the entered element is correct?
import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
public class Array_Search extends JFrame {
String myString[] = { "1", "2", "3", "4", "5" };
public String[] get_Element() {
String str[] = new String[myString.length];
str = myString;
return str;
}
public Array_Search() {
Container pane = getContentPane();
JPanel panel = new JPanel();
final JTextField txt = new JTextField(
" ");
JButton b = new JButton("Click Me ");
panel.add(b);
panel.add(txt);
pane.add(panel);
b.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
String[] str = get_Element();
String s2 = txt.getText().trim();
if (s2 != null && s2.length() > 0)
for (int i = 0; i < str.length; i++) {
if (s2.equals(str[i].trim())) {
JOptionPane option = new JOptionPane();
option.showInputDialog("" + str[i]);
} else {
JOptionPane option = new JOptionPane();
option.showInputDialog("Number Entered is not found in myArray");
}
}
else {
JOptionPane o = new JOptionPane();
o.showInputDialog("please Enter something");
}
}
});
}
public static void main(String[] args) {
Array_Search myArray = new Array_Search();
myArray.setSize(500, 500);
myArray.setVisible(true);
}
}

Your code shows message every time when non-matching element is found.
Instead, you need to look through all of the elements and display Not found message after that.
Something like this should work:
...
if (s2 != null && s2.length() > 0) {
boolean isFound = false;
for (int i = 0; i < str.length; i++) {
if (s2.equals(str[i].trim())) {
JOptionPane option = new JOptionPane();
option.showInputDialog("" + str[i]);
isFound = true;
break;
}
}
if(!isFound) {
JOptionPane option = new JOptionPane();
option.showInputDialog("Number Entered is not found in myArray");
}
} else
...

You return an empty Array in your get_Element method.
Can be fixed like that:
public void actionPerformed(ActionEvent ae) {
String [] str = get_Element(); // replace this
String [] str = myString; // with this
or change get_Element to:
public String[] get_Element() {
return myString;
}
Note: by Java code conventions use camel case for method names. getElement instead of get_Element.

How to issue a warning if required text field is empty?

I am trying to make an executable JButton (which opens a new window)radiobutton is chosen and the textfiled is filled within a specific range (the textfield should be from 1800 to 2013) . For the radiobuttons I made a default choise for now, but I cannot figure out how can I return a warning that the textfield should be filled (a number between 1800 and 2013) and if it is there then it run the program.
EDIT:
So if my code is:
JFrame ....
JPanel ....
JTextField txt = new JTextField();
JButton button = new JButton("run");
button.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e) {
//Do things here
}
});
txt.addFocusListener(new FocusListener() {
....
}
how can I use the ItemStateListener. Should I define a listener and then what?

public void actionPerformed(ActionEvent e)
{
String s = txt.getText();
char[] cArr = s.toCharAray();
ArrayList<Character> chars = new ArrayList<Character>();
for (char c : cArr)
if (c.isDigit())
chars.add(c);
cArr = new char[chars.size()];
for (int i = 0;i<chars.size();i++)
cArr[i] = char.get(i);
s = new String(cArr);
txtField.setText(s);
if (s.equals(""))
{
// issue warning
return;
}
int input = Integer.parseInt(s);
if (input >= 1800 && input <= 2013)
{
// do stuff
}
}
Basically, read the string in the text field, remove all non-numeric characters from it, and only proceed if it is in the range specified.