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Random Number won't appear in a JTextField

I have a problem.I created a program that will add two random numbers. I'm trying to put a Math.random() in a JTextField but it won't appear. Here's my code by the way:
public class RandomMathGame extends JFrame {
public RandomMathGame(){
super("Random Math Game");
int random2;
JButton lvl1 = new JButton("LEVEL 1");
JButton lvl2 = new JButton("LEVEL 2");
JButton lvl3 = new JButton("LEVEL 3");
JLabel line1 = new JLabel("Line 1: ");
final JTextField jtf1 = new JTextField(10);
JLabel line2 = new JLabel("Line 2: ");
final JTextField jtf2 = new JTextField(10);
JLabel result = new JLabel("Result: ");
final JTextField jtf3 = new JTextField(10);
JButton ans = new JButton("Answer");
JLabel score = new JLabel("Score: ");
JTextField jtf4 = new JTextField(3);
JLabel itm = new JLabel("Number of Items: ");
JTextField items = new JTextField(3);
FlowLayout flo = new FlowLayout();
setLayout(flo);
add(lvl1);
add(lvl2);
add(lvl3);
add(line1);
add(jtf1);
add(line2);
add(jtf2);
add(result);
add(jtf3);
add(ans);
add(score);
add(jtf4);
add(itm);
add(items);
setSize(140,400);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
lvl1.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
int i, j = 10;
int i1 = Integer.valueOf(jtf1.getText());
int i2 = Integer.valueOf(jtf2.getText());
int i3 = i1 + i2;
final int random1 = (int)(Math.random() * 10 + 1);
for (i = 0; i <= j + 1; i++){
try{
jtf1.setText(String.valueOf(random1));
jtf2.setText(String.valueOf(random1));
jtf3.setText(String.valueOf(i3));
}catch(Exception ex){
ex.printStackTrace();
}
}
}
});
}
Never mind the lvl2 and lvl3 because it's the same in lvl1. And also, I want to loop them 10 times. I'm having difficulties on putting up those codes. Can someone help me? Thanks for your help. :)

Updating text fields in a loop won't produce the animated display that you likely want; only the last update will be seen. Instead, use a javax.swing.Timer to periodically update the fields. Related examples may be found here, here and here.

How do I make my code find out which button was pressed within a reasonable amount of time?

Alright, this one is a bit of a doozy, its about 240 lines long, but on to my point. The point is that it doesn't work. I'm pretty new to coding in general and some help would be really appreciated. I know where the problem is, it's in the last bits of it in the for loops, I went under the false presumption that if you click a JButton, it is then selected. How do I implement the .setSelected method to my program without rewriting the entire code? This code is a make-shift jeopardy of sorts btw.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import sun.audio.*;
import java.io.*;
public class Jeopardy implements ActionListener
{
public static JFrame frame = new JFrame("Jeopardy!");
public static JButton[] row1Buttons = new JButton[6];
public static JButton[] row2Buttons = new JButton[6];
public static JButton[] row3Buttons = new JButton[6];
public static JButton[] row4Buttons = new JButton[6];
public static JButton[] row5Buttons = new JButton[6];
//Creates 5 arrays, each with 6 JButtons in each (otherwise mass confusion
//is going to ensue because I would have to individually add 30 JButtons to the pane,
//all of which I would have to remember what they contain.)
public static JPanel pane = new JPanel();
public static JLabel[] labels = new JLabel[6];
//Creates an array of 6 JLabels
public static void main(String[] args)
{
frame.setSize(800, 600);
frame.setVisible(true);
frame.toFront();
frame.setContentPane(pane);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Font font = new Font("ComicSans", Font.PLAIN, 20);
Color colour = new Color(0, 0, 240);
for(int a = 0; a < row1Buttons.length; a++)
{
row1Buttons[a] = new JButton("$200");
row2Buttons[a] = new JButton("$400");
row3Buttons[a] = new JButton("$600");
row4Buttons[a] = new JButton("$800");
row5Buttons[a] = new JButton("$1000");
//Gives text to all 30 JButtons
row1Buttons[a].addActionListener(new Jeopardy());
row2Buttons[a].addActionListener(new Jeopardy());
row3Buttons[a].addActionListener(new Jeopardy());
row4Buttons[a].addActionListener(new Jeopardy());
row5Buttons[a].addActionListener(new Jeopardy());
//adds action listener to all 30
row1Buttons[a].setBackground(colour);
row2Buttons[a].setBackground(colour);
row3Buttons[a].setBackground(colour);
row4Buttons[a].setBackground(colour);
row5Buttons[a].setBackground(colour);
//sets background colour
row1Buttons[a].setForeground(Color.yellow);
row2Buttons[a].setForeground(Color.yellow);
row3Buttons[a].setForeground(Color.yellow);
row4Buttons[a].setForeground(Color.yellow);
row5Buttons[a].setForeground(Color.yellow);
}
labels[0] = new JLabel("Mathematics");
labels[1] = new JLabel("Computer Science");
labels[2] = new JLabel("Historical Events");
labels[3] = new JLabel("Chemistry");
labels[4] = new JLabel("TBD");
labels[5] = new JLabel("TBD");
for(int k = 0; k < labels.length; k++)
{
labels[k].setForeground(Color.yellow);
}
pane.setLayout(new GridLayout(6, 6, 6, 6));
for(int b = 0; b < labels.length; b++)
{
pane.add(labels[b]);
pane.add(row1Buttons[b]);
pane.add(row2Buttons[b]);
pane.add(row3Buttons[b]);
pane.add(row4Buttons[b]);
pane.add(row5Buttons[b]);
}
pane.setBackground(Color.blue);
}
public void actionPerformed(ActionEvent event)
{
String[] answerRow1 = new String[6];
String[] answerRow2 = new String[6];
String[] answerRow3 = new String[6];
String[] answerRow4 = new String[6];
String[] answerRow5 = new String[6];
String[] questionsRow1 = new String[6];
//Write $200 questions
questionsRow1[0] = "Question";
questionsRow1[1] = "Question";
questionsRow1[2] = "Question";
questionsRow1[3] = "Question";
questionsRow1[4] = "Question";
questionsRow1[5] = "Question";
String[] questionsRow2 = new String[6];
//Write $400 questions
questionsRow2[0] = "Question";
questionsRow2[1] = "Question";
questionsRow2[2] = "Question";
questionsRow2[3] = "Question";
questionsRow2[4] = "Question";
questionsRow2[5] = "Question";
String[] questionsRow3 = new String[6];
//Write $600 questions
questionsRow3[0] = ("The function y=3(2)^x will have this for a y value when x = 3.");
questionsRow3[1] = "Question";
questionsRow3[2] = "Question";
questionsRow3[3] = "Question";
questionsRow3[4] = "Question";
questionsRow3[5] = "Question";
String[] questionsRow4 = new String[6];
//Write $800 questions
questionsRow4[0] = "Question";
questionsRow4[1] = "Question";
questionsRow4[2] = "Question";
questionsRow4[3] = "Question";
questionsRow4[4] = "Question";
questionsRow4[5] = "Question";
String[] questionsRow5 = new String[6];
//Write $1000 questions
questionsRow5[0] = "Question";
questionsRow5[1] = "Question";
questionsRow5[2] = "Question";
questionsRow5[3] = "Question";
questionsRow5[4] = "Question";
questionsRow5[5] = "Question";
for(int j = 0; j < questionsRow1.length; j++)
{
if(row1Buttons[j].getModel().isPressed())
{
try
{
InputStream in = new FileInputStream("sounds/x.wav");
AudioStream openSound = new AudioStream(in);
AudioPlayer.player.start(openSound);
}
catch(Exception e)
{
JOptionPane.showMessageDialog(null, "You don't have the sound clip for this");
}
answerRow1[j] = JOptionPane.showInputDialog(null, questionsRow1[j]);
}
}
for(int a = 0; a < questionsRow2.length; a++)
{
if(row2Buttons[a].isSelected())
{
try
{
InputStream in = new FileInputStream("sounds/x.wav");
AudioStream openSound = new AudioStream(in);
AudioPlayer.player.start(openSound);
}
catch(Exception e)
{
JOptionPane.showMessageDialog(null, "You don't have the sound clip for this");
}
JOptionPane.showInputDialog(null, questionsRow2[a]);
}
}
for(int r = 0; r < questionsRow3.length; r++)
{
if(row3Buttons[r].isSelected())
{
try
{
InputStream in = new FileInputStream("sounds/x.wav");
AudioStream openSound = new AudioStream(in);
AudioPlayer.player.start(openSound);
}
catch(Exception e)
{
JOptionPane.showMessageDialog(null, "You don't have the sound clip for this");
}
JOptionPane.showInputDialog(null, questionsRow3[r]);
}
}
for(int e = 0; e < questionsRow4.length; e++)
{
if(row4Buttons[e].isSelected())
{
try
{
InputStream in = new FileInputStream("sounds/x.wav");
AudioStream openSound = new AudioStream(in);
AudioPlayer.player.start(openSound);
}
catch(Exception exception)
{
JOptionPane.showMessageDialog(null, "You don't have the sound clip for this");
}
JOptionPane.showInputDialog(null, questionsRow4[e]);
}
}
for(int d = 0; d < questionsRow5.length; d++)
{
if(row5Buttons[d].isSelected())
{
try
{
InputStream in = new FileInputStream("sounds/x.wav");
AudioStream openSound = new AudioStream(in);
AudioPlayer.player.start(openSound);
}
catch(Exception e)
{
JOptionPane.showMessageDialog(null, "You don't have the sound clip for this");
}
JOptionPane.showInputDialog(null, questionsRow5[d]);
}
}
}
}

The problem is that you make the frame visible and then add your components. Instead, call setVisible() at the end of your constructor, after you pack() the frame.
public static void main(String[] args) {
...
pane.setBackground(Color.blue);
frame.pack();
frame.setVisible(true);
}

try to create a new class for buttons
public class Response_Button extends JButton {
public Response_Button(final JPanel container, final String name) {
this.setText(name);
this.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
JOptionPane.showMessageDialog(container, "clicked " + name);
}
});
}
like this each button will respond through it's own method

This is what fixes it:
if(event.getSource()== row1Buttons[j])
Yes, that makes it so that it will do all of the category in one fell swoop, but it doesn't matter. Thanks for all who tried and gave positive and helpful answers.
EDIT: nope, it doesn't do it all in one go, I just labeled it wrong.

Displaying an array of Strings in a JTextArea

i've been stuck on getting one of my JTextArea's to display an array of Strings that represent letters in a word in a hangman game. Once the user guesses a letter, (assuming it's right), it should reflect into the array. Instead, it seems to be only adding the letter that was guessed, and not the blanks or the rest of the array. I want to set the guessed letter equal to the correct index in the array and then have it shown on the screen. Here is my code:
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Random;
#SuppressWarnings("serial")
public class GuiClass extends JFrame {
char guess = ' ';
int numGuesses = 0;
char[] letterGuessedAgainst = null;
String wordInPlay = " ";
String[] hangmanScores = null;
ArrayList<Character> wrongGuesses = null;
boolean isGuessSuccessfull = false;
private Container contents;
JRadioButton rbEasy;
JRadioButton rbHard;
ButtonGroup difficultyGroup;
JTextField txtfldWord;
JTextArea txtareaWord;
JLabel difficultyPrompt;
JLabel userDifficulty;
JButton btnStartGame;
JButton btnGuessSubmit;
JButton btnWordGuessSubmit;
JPanel topPanel;
JPanel midPanel;
JLabel topLabel;
JPanel guessPanel;
JPanel letterPanel;
JLabel word;
JTextArea txtareaNumGuesses;
JTextField txtfldGuess;
JTextField txtfldWordGuess;
JTextArea txtareaguessedLetters;
JTextArea txtareaLettersLeft;
public GuiClass(){
super("Hangman GUI");
contents = getContentPane();
//create a new panel & set layout
midPanel = new JPanel();
midPanel.setLayout(new GridLayout(3,3));
//layout manager
topLabel = new JLabel("Welcome to Hangman!");
contents.setLayout(new FlowLayout());
//create new ButtonHandlers
ButtonHandler buttonHandler = new ButtonHandler();
ButtonHandler2 btnHndlrNewGame = new ButtonHandler2();
//create difficulty buttons/labels & add ActionListeners
difficultyPrompt = new JLabel("First, Choose A Difficulty:");
rbEasy = new JRadioButton("Easy");
rbHard = new JRadioButton("Hard");
userDifficulty = new JLabel("Game Difficulty: ");
difficultyGroup = new ButtonGroup();
difficultyGroup.add(rbEasy);
difficultyGroup.add(rbHard);
rbEasy.addItemListener(buttonHandler);
rbHard.addItemListener(buttonHandler);
midPanel.add(topLabel);
midPanel.add(difficultyPrompt);
midPanel.add(rbEasy);
midPanel.add(rbHard);
midPanel.add(userDifficulty);
topPanel = new JPanel();
JLabel btnStartNewGame = new JLabel("Next, Start a new game!");
btnStartGame = new JButton("Start A New Game");
btnStartGame.addActionListener(btnHndlrNewGame);
topPanel.add(btnStartNewGame);
topPanel.add(btnStartGame);
guessPanel = new JPanel();
JLabel lblGuess = new JLabel("Guess: ");
JLabel lblWordGuess = new JLabel("Word Guess: ");
btnGuessSubmit = new JButton("Submit");
btnGuessSubmit.addActionListener(btnHndlrNewGame);
btnWordGuessSubmit = new JButton("Submit");
btnGuessSubmit.addActionListener(btnHndlrNewGame);
txtfldGuess = new JTextField(10);
txtfldWordGuess = new JTextField(10);
guessPanel.add(lblGuess);
guessPanel.add(txtfldGuess);
guessPanel.add(btnGuessSubmit);
guessPanel.add(lblWordGuess);
guessPanel.add(txtfldWordGuess);
guessPanel.add(btnWordGuessSubmit);
letterPanel = new JPanel();
JLabel lblGuessedLetters = new JLabel("Guessed Letters:");
JLabel lblLettersInWord = new JLabel("Letters Left:");
JLabel lblNumGuesses = new JLabel("Guess Number: ");
txtareaNumGuesses = new JTextArea(5,5);
txtareaNumGuesses.setEditable(false);
txtareaguessedLetters = new JTextArea(5,15);
txtareaguessedLetters.setEditable(false);
txtareaLettersLeft = new JTextArea(5,15);
txtareaLettersLeft.setEditable(false);
letterPanel.add(lblGuessedLetters);
letterPanel.add(txtareaguessedLetters);
letterPanel.add(lblLettersInWord);
letterPanel.add(txtareaLettersLeft);
letterPanel.add(lblNumGuesses);
letterPanel.add(txtareaNumGuesses);
JPanel wordPanel = new JPanel();
word = new JLabel("Word is: ");
//txtfldWord = new JTextField(10);
txtareaWord = new JTextArea(20,20);
//txtfldWord.setEditable(false);
txtareaWord.setEditable(false);
wordPanel.add(word);
//wordPanel.add(txtfldWord);
wordPanel.add(txtareaWord);
//add contents of panels to the container
contents.add(midPanel);
contents.add(topPanel);
contents.add(guessPanel);
contents.add(letterPanel);
contents.add(wordPanel);
setSize(800,600);
setVisible(true);
}//end constructor
private class ButtonHandler implements ItemListener{
public void itemStateChanged(ItemEvent ie){
if (ie.getSource()==rbEasy){
userDifficulty.setText("Game Difficulty: Easy");
}//end if
if (ie.getSource()==rbHard){
userDifficulty.setText("Game Difficulty: Hard");
}//end if
}//end method
}//end ButtonHandler inner class
private class ButtonHandler2 implements ActionListener{
public void actionPerformed(ActionEvent ae){
if (ae.getSource()==btnStartGame){
if (rbEasy.isSelected()){
ArrayList<String> easyHmWords = new ArrayList<String>();
String filename = "easyhangmanwords.txt";
BufferedReader infile = null;
try {
infile = new BufferedReader(new FileReader(filename));
}//end try
catch (FileNotFoundException e) {
e.getMessage();
}//end catch
String re = "";
try {
while ((re=infile.readLine())!=null){ // reading one line
easyHmWords.add(re);
}//end while
System.out.println("words in file: "+easyHmWords);
}//end try
catch (IOException e) {
e.getMessage();
}//end while
try {
infile.close();
}//end try
catch (IOException e) {
e.getMessage();
}//end catch
wordInPlay = "";
int randomNumber = 0;
Random rand = new Random();
int maxRandomNumber = 0;
word.setText("Word is: Set");
//System.out.println("Okay, the word is set!");
maxRandomNumber = easyHmWords.size();
System.out.println("Size of arraylist: "+easyHmWords.size());
randomNumber = rand.nextInt(maxRandomNumber);
System.out.println("random num: "+randomNumber);
wordInPlay = easyHmWords.get(randomNumber);
System.out.println("word in play: "+wordInPlay);
//figures out how many letters the word has
int lettersInWord = wordInPlay.length();
System.out.println("Letters in word: "+lettersInWord);
//creates an array of hangman scores which is the size of the letters in the word
hangmanScores = new String[lettersInWord];
//for loop to iterate through the array and assign "_" to the spaces
for (int i = 0; i < hangmanScores.length; i++) {
hangmanScores[i] = " _ ";
}//end for
for (int i = 0; i < hangmanScores.length; i++){
//txtareaWord.setText(hangmanScores[i]);
//txtfldWord.append(hangmanScores[i]);
txtareaWord.append((hangmanScores[i]));
}//end for
}//end if
}//end if
if(btnGuessSubmit == ae.getSource()){ //getting problems in this if statement
guess = txtfldGuess.getText().charAt(0);
letterGuessedAgainst = wordInPlay.toCharArray();
for (int i = 0; i < letterGuessedAgainst.length; i++) {//goes through the letters of the word in play
***if(letterGuessedAgainst[i]==guess){//if a letter matches up,
hangmanScores[i] = Character.toString(guess);
isGuessSuccessfull = true;
}//end if
}//end for
for (int k =0; k < hangmanScores.length; k++){//displays the ______ in the text area
txtareaWord.setText((hangmanScores[k]));***
System.out.print(hangmanScores[k]);//testing purposes
}//end for
numGuesses++;
txtareaNumGuesses.setText(" "+numGuesses);
}//end for
if(isGuessSuccessfull = false){
wrongGuesses.add(guess);
txtareaguessedLetters.append(wrongGuesses+"");
}//end if
}//end method
}//end private inner class
public static void main (String[] args){
GuiClass estGUI = new GuiClass();
estGUI.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}//end main method
}//end class
this is the part of the code that doesn't display the correct parts of the array:
***if(letterGuessedAgainst[i]==guess){//if a letter matches up,
hangmanScores[i] = Character.toString(guess);
isGuessSuccessfull = true;
}//end if
}//end for
for (int k =0; k < hangmanScores.length; k++){
txtareaWord.setText((hangmanScores[k]));***

Basically, you are calling setText every time you want to add a new character to the JTextArea in question, this is, first, clearing any existing text and then adding the new String, which, in this case, is the last thing you entered.
There are a few ways you could fix this, but because you want to remove the existing text first and then replace it, it's probably better to build a buffer of what you want and apply it all in a single step...
StringBuilder sb = new StringBuilder(hangmanScores.length);
for (int k = 0; k < hangmanScores.length; k++) {//displays the ______ in the text area
sb.append(hangmanScores[k]);
System.out.print(hangmanScores[k]);//testing purposes
}//end for
txtareaWord.setText(sb.toString());
You also seem to have attached multiple ActionListeners to your button, as each time I clicked it, it counted for two guesses...

Connect a java class to a separate GUI Jpanel button and/or textarea?

So im linking a java class with array lists and a random array generator to a separate GUI in the same project. Its a Jeopardy Game, so I need the buttons to "get" the strings from the array list and "check" the answer in another. I need to know how to make the GUI "get" info from the other "classes". Thanks.
(Question&Answer Class Example)
Random generator = new Random();
int random_int = generator.nextInt(10) + 1;
double random_int = Math.random() * ( 0 - 24 );
String[] am = new String[25];
String[] ama = new String[25];
am[0] = "Sam";ama[0] = "Sam";
am[1] = "Sam";ama[1] = "Sam";
am[2] = "Sam";ama[2] = "Sam";
...
am[23] = "Sam";ama[23] = "Sam";
am[24] = "Sam";ama[24] = "Sam";
String am_qu = am[random_int];
String am_an = ama[random_int];
(GUI Jpanel button "Action" Example)
private void am1ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
JOptionPane.showMessageDialog(null,""+am_qu+); <--That is what I need to work!
}
The Jeopardy game will have buttons that you click which will show dialog box with question, a button that says answer and when that is clicked it will open an input box to check answer after the final submit.

I'm not entirely sure how your project is set up, or why your code isn't working, but here's a working snippet I literally just shoved into a JFrame of mine:
final Random generator = new Random();
final String[] am = new String[25];
final String[] ama = new String[25];
for(int n = 0; n < 25; n++) {
am[n] = "Sam " + n + " (Q)";
ama[n] = "Sam " + n + " (A)";
}
JButton testButton = new JButton("Click This!");
testButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent arg0) {
final int random_int = generator.nextInt(24) + 1;
System.out.println(random_int);
JOptionPane.showMessageDialog(null, am[random_int] + " " + ama[random_int]);
}
});
See the image below for output:

passing array of string from one class to another

I'm trying to pass a string array from one class to another in my java code. By using code such as
Class instanceofclass = new Class();
String text1 = instanceofclass.variablename;
and then displaying it out on screen worked fine!
However I'm trying to get the array of a string. So in my first class I have
JButton [] FilmTime = new JButton[5];
JButton [] FilmNames = new JButton[8];
String [] films = new String [8];
DbConnector dataBase = new DbConnector();
for (int i =0; i <= 7; i++)
{
films[i] = dataBase.FilmTitle[i];
}
for (int i =0; i<= 7; i++)
{
FilmNames[i] = new JButton (films[i] + " ("+age+")");
FilmNames[i].setPreferredSize(new Dimension(563,50));
grid.add(FilmNames[i]);
}
I know I can use one for loop but I was just checking issues at the momment.
In my second class used named dbconnector i have:
public String FilmTitle [];
for (int i =0; i<=7; i++)
{
String query = "SELECT * FROM films WHERE ID =" + i;
Rs = St.executeQuery(query);
while (Rs.next())
{
FilmTitle[i] = Rs.getString("FilmName");
}
}
Eclipse gives the error as:
Error is: java.lang.NullPointerException
java.lang.NullPointerException
at main.init(main.java:46)
at sun.applet.AppletPanel.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Line 46 is the statement in the first for loop...
testingme[i] = instanceofclass.variablename[i];

You have to initialize string array.
String[] testingme = new String[8];