import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.*;
import java.util.*;
import java.util.List;
import javax.swing.*;


public class Hangman {
 String[] wordList;
 String secretWord;
 Set<Character> alphabet;
 Set<Character> lettersGuessed; // letters the user has guessed
 boolean[] lettersRevealed; // determines if the letter should be revealed or not

 int GuessesRemaining;

 // GUI
 JFrame f;
 JTextField textField;
 JLabel guessesRemainingLabel;
 JLabel lettersGuessedLabel;
 JLabel secretWordLabel;


 public static void main(String[] args){
 Hangman h = new Hangman();
 h.createAlphabetSet();
 h.readFile("words.txt");
 h.buildGUI();
 h.setUpGame();
 h.drawSecretWord();
 }

 // buildGUI - builds the GUI
 private void buildGUI(){
 f = new JFrame("Hangman");

 // JLabels
 guessesRemainingLabel = new JLabel("Guesses remaining: " + String.valueOf(GuessesRemaining));
 lettersGuessedLabel = new JLabel("Already guessed: ");
 secretWordLabel = new JLabel();

 // Text field for user to type letters in
 textField = new JTextField();
 JButton checkButton = new JButton("Guess");

 // Add listeners to textField & checkButton
 TextListener textListener = new TextListener();
 checkButton.addActionListener(textListener);
 textField.addActionListener(textListener);

 // Panel for all the labels
 JPanel labelPanel = new JPanel();
 labelPanel.setLayout(new BoxLayout(labelPanel, BoxLayout.PAGE_AXIS));
 labelPanel.add(guessesRemainingLabel);
 labelPanel.add(lettersGuessedLabel);
 labelPanel.add(secretWordLabel);

 // User panel
 JPanel userPanel = new JPanel(new BorderLayout());
 userPanel.add(BorderLayout.CENTER, textField);
 userPanel.add(BorderLayout.EAST, checkButton);
 labelPanel.add(userPanel);

 // Add everything to frame
 f.add(BorderLayout.CENTER, labelPanel);

 f.setSize(250, 100);
 f.setLocationRelativeTo(null);
 f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
 f.setVisible(true);
 }
 // checkIfWon - sees if the user has won the game
 private boolean checkIfWon(){
 for(boolean tof : lettersRevealed){
 if(!tof)
 return false;
 }
 return true;
 }
 
 // get input from the user
 private boolean checkUserGuess(String l){
 if(l.length() == 1 && !lettersGuessed.contains(l.charAt(0)) && alphabet.contains(l.charAt(0))) {
 setText(null);
 lettersGuessed.add(l.charAt(0));
 return true;
 }else {
 Toolkit.getDefaultToolkit().beep();
 }
 return false;
 }
 
 // chooseSecretWord - selects a word
 private String chooseSecretWord(String[] wordList){
 return wordList[(int)(Math.random() * wordList.length)];
 }
 
 // createAlphabetSet - Creates the alphabet set that's used to ensure that the user's guess not a number nor a special character
 private void createAlphabetSet(){
 alphabet = new HashSet<Character>(26);
 for(Character c = 'a'; c<='z'; c++){
 alphabet.add(c);
 }
 }
 
 // drawGuessesRemaining - Outputs the guesses remaining
 void drawGuessesRemaining(){
 final String guessesMessage = "Guesses remaining: " + String.valueOf(GuessesRemaining);
 SwingUtilities.invokeLater(
 new Runnable(){
 @Override
 public void run(){
 guessesRemainingLabel.setText(guessesMessage);
 guessesRemainingLabel.setAlignmentX(Component.LEFT_ALIGNMENT);
 }
 }
 );
 }
 
 // drawLettersGuessed - Outputs the letters guessed
 void drawLettersGuessed(){
 StringBuilder lettersBuilder = new StringBuilder();
 for (Character el : lettersGuessed) {
 String s = el + " ";
 lettersBuilder.append(s);
 }
 
 final String letters = lettersBuilder.toString();
 SwingUtilities.invokeLater(
 new Runnable() {
 @Override
 public void run() {
 lettersGuessedLabel.setText("Already guessed: " + letters);
 }
 }
 );
 }
 
 // drawSecretWord - draws the secret word with dashes & etc for user to use to guess the word with
 private void drawSecretWord(){
 StringBuilder word = new StringBuilder();
 for(int i=0; i<lettersRevealed.length; i++){
 
 if(lettersRevealed[i]){
 String s = secretWord.charAt(i) + " ";
 word.append(s);
 }else{
 word.append("_ ");
 }
 }
 
 final String w = word.toString();
 SwingUtilities.invokeLater(
 new Runnable(){
 @Override
 public void run(){
 secretWordLabel.setText(w);
 }
 }
 );
 }
 
 // loseSequence - when the the user runs out of guesses
 private void loseSequence(){
 for(int i=0; i<lettersRevealed.length; i++)
 lettersRevealed[i] = true;
 drawSecretWord();
 playAgain("Tough luck. The secret word was " + secretWord + ".\nWould you like to play another game of hangman?");
 }
 
 // playAgain - Allows the user to play another game of hangman
 private void playAgain(String message){
 int ans = JOptionPane.showConfirmDialog(f, message,
 "Play again?", JOptionPane.YES_NO_OPTION, JOptionPane.PLAIN_MESSAGE);
 if(ans == JOptionPane.YES_OPTION) {
 setUpGame();
 }else {
 System.exit(0);
 }
 }
 
 // readFile - read in wordList
 private String[] readFile(String loc){
 try {
 File f = new File(loc);
 assert f.exists() : "File doesn't exist";
 
 BufferedReader input = new BufferedReader(new FileReader(f));
 
 // read in the stuff into an arrayList here
 wordList = input.readLine().split(" ");
 // close the input stream
 input.close();
 }catch(IOException ioException){
 ioException.printStackTrace();
 }
 return wordList;
 }
 // setUpGame - sets up the variables appropriately
  private void setUpGame(){
  GuessesRemaining = 5;
 secretWord = chooseSecretWord(wordList);
 lettersRevealed = new boolean[secretWord.length()];
 Arrays.fill(lettersRevealed, false);
  lettersGuessed = new HashSet<Character>(26); // 26 letters in alphabet
 
 drawSecretWord();
 drawLettersGuessed();
 drawGuessesRemaining();
 }
 
 // updateSecretWord - updates which letters of the secret word have been revealed
 private void updateSecretWord(String l){
 List<Integer> changeBool = new ArrayList<Integer>();
 
 if(secretWord.contains(l)){
 // Searches through secretWord & notes down all letters that equal the user's guess
 for(int i=0; i<secretWord.length(); i++){
 if(secretWord.charAt(i) == l.charAt(0))
 changeBool.add(i);
 }

 // Changes the boolean value for those letters @ their corresponding indexes
 for(Integer idx : changeBool)
 lettersRevealed[idx] = true;
 }else{
 GuessesRemaining--;
 drawGuessesRemaining();
 }
 }
 
 // winSequence - when the user has correctly guessed the secret word
 private void winSequence(){
 playAgain("Well done! You guessed " + secretWord + " with " + GuessesRemaining + " guesses left!\n" +
 "Would you like to play another game of hangman?");
 }




 // GETTERS
 private String getText(){
 return textField.getText();
 }


 // SETTERS
 private void setText(final String t){
 SwingUtilities.invokeLater(
 new Runnable(){
 @Override
 public void run(){
 textField.setText(t);
 }
 }
 );
 }
 
 
 // ActionListener
 private class TextListener implements ActionListener {
 @Override
 public void actionPerformed(ActionEvent ev){
 String guess = getText();
 
 if(checkUserGuess(guess)) {
 updateSecretWord(guess);
 drawSecretWord();
 
 if(lettersGuessed.size() != 0) // No letters have been guessed by the user at the beginning
 drawLettersGuessed();
 
 // Checks if the user has won or lost
 if (checkIfWon())
 winSequence();
 else if (GuessesRemaining == 0)
 loseSequence();
 }
 }
 }
 }

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.*;
import java.util.*;
import java.util.List;
import javax.swing.*;
public class Hangman {
 String[] wordList;
 String secretWord;
 Set<Character> alphabet;
 Set<Character> lettersGuessed; // letters the user has guessed
 boolean[] lettersRevealed; // determines if the letter should be revealed or not
 int GuessesRemaining;
 // GUI
 JFrame f;
 JTextField textField;
 JLabel guessesRemainingLabel;
 JLabel lettersGuessedLabel;
 JLabel secretWordLabel;
 public static void main(String[] args){
 Hangman h = new Hangman();
 h.createAlphabetSet();
 h.readFile("words.txt");
 h.buildGUI();
 h.setUpGame();
 h.drawSecretWord();
 }
 // buildGUI - builds the GUI
 private void buildGUI(){
 f = new JFrame("Hangman");
 // JLabels
 guessesRemainingLabel = new JLabel("Guesses remaining: " + String.valueOf(GuessesRemaining));
 lettersGuessedLabel = new JLabel("Already guessed: ");
 secretWordLabel = new JLabel();
 // Text field for user to type letters in
 textField = new JTextField();
 JButton checkButton = new JButton("Guess");
 // Add listeners to textField & checkButton
 TextListener textListener = new TextListener();
 checkButton.addActionListener(textListener);
 textField.addActionListener(textListener);
 // Panel for all the labels
 JPanel labelPanel = new JPanel();
 labelPanel.setLayout(new BoxLayout(labelPanel, BoxLayout.PAGE_AXIS));
 labelPanel.add(guessesRemainingLabel);
 labelPanel.add(lettersGuessedLabel);
 labelPanel.add(secretWordLabel);
 // User panel
 JPanel userPanel = new JPanel(new BorderLayout());
 userPanel.add(BorderLayout.CENTER, textField);
 userPanel.add(BorderLayout.EAST, checkButton);
 labelPanel.add(userPanel);
 // Add everything to frame
 f.add(BorderLayout.CENTER, labelPanel);
 f.setSize(250, 100);
 f.setLocationRelativeTo(null);
 f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
 f.setVisible(true);
 }
 // checkIfWon - sees if the user has won the game
 private boolean checkIfWon(){
 for(boolean tof : lettersRevealed){
 if(!tof)
 return false;
 }
 return true;
 }
 // get input from the user
 private boolean checkUserGuess(String l){
 if(l.length() == 1 && !lettersGuessed.contains(l.charAt(0)) && alphabet.contains(l.charAt(0))){
 setText(null);
 lettersGuessed.add(l.charAt(0));
 return true;
 }else {
 Toolkit.getDefaultToolkit().beep();
 }
 return false;
 }
 // chooseSecretWord - selects a word
 private String chooseSecretWord(String[] wordList){
 return wordList[(int)(Math.random() * wordList.length)];
 }
 // createAlphabetSet - Creates the alphabet set that's used to ensure that the user's guess not a number nor a special character
 private void createAlphabetSet(){
 alphabet = new HashSet<Character>(26);
 for(Character c = 'a'; c<='z'; c++){
 alphabet.add(c);
 }
 }
 // drawGuessesRemaining - Outputs the guesses remaining
 void drawGuessesRemaining(){
 final String guessesMessage = "Guesses remaining: " + String.valueOf(GuessesRemaining);
 SwingUtilities.invokeLater(
 new Runnable(){
 @Override
 public void run(){
 guessesRemainingLabel.setText(guessesMessage);
 guessesRemainingLabel.setAlignmentX(Component.LEFT_ALIGNMENT);
 }
 }
 );
 }
 // drawLettersGuessed - Outputs the letters guessed
 void drawLettersGuessed(){
 StringBuilder lettersBuilder = new StringBuilder();
 for (Character el : lettersGuessed) {
 String s = el + " ";
 lettersBuilder.append(s);
 }
 final String letters = lettersBuilder.toString();
 SwingUtilities.invokeLater(
 new Runnable() {
 @Override
 public void run() {
 lettersGuessedLabel.setText("Already guessed: " + letters);
 }
 }
 );
 }
 // drawSecretWord - draws the secret word with dashes & etc for user to use to guess the word with
 private void drawSecretWord(){
 StringBuilder word = new StringBuilder();
 for(int i=0; i<lettersRevealed.length; i++){
 if(lettersRevealed[i]){
 String s = secretWord.charAt(i) + " ";
 word.append(s);
 }else{
 word.append("_ ");
 }
 }

 final String w = word.toString();
  SwingUtilities.invokeLater(
 new Runnable(){
  @Override
 public void run(){
  secretWordLabel.setText(w);
 }
 }
 );
 }
 // loseSequence - when the the user runs out of guesses
 private void loseSequence(){
 for(int i=0; i<lettersRevealed.length; i++)
 lettersRevealed[i] = true;
 drawSecretWord();
 playAgain("Tough luck. The secret word was " + secretWord + ".\nWould you like to play another game of hangman?");
 }
 // playAgain - Allows the user to play another game of hangman
 private void playAgain(String message){
 int ans = JOptionPane.showConfirmDialog(f, message,
 "Play again?", JOptionPane.YES_NO_OPTION, JOptionPane.PLAIN_MESSAGE);
 if(ans == JOptionPane.YES_OPTION) {
 setUpGame();
 }else {
 System.exit(0);
 }
 }
 // readFile - read in wordList
 private String[] readFile(String loc){
 try {
 File f = new File(loc);
 assert f.exists() : "File doesn't exist";
 BufferedReader input = new BufferedReader(new FileReader(f));
 // read in the stuff into an arrayList here
 wordList = input.readLine().split(" ");
 // close the input stream
 input.close();
 }catch(IOException ioException){
  ioException.printStackTrace();
 }
 return wordList;
 }
 // setUpGame - sets up the variables appropriately
 private void setUpGame(){
 GuessesRemaining = 5;
 secretWord = chooseSecretWord(wordList);
  lettersRevealed = new boolean[secretWord.length()];
 Arrays.fill(lettersRevealed, false);
 lettersGuessed = new HashSet<Character>(26);  // 26 letters in alphabet

 drawSecretWord();
 drawLettersGuessed();
  drawGuessesRemaining();
 }
 // updateSecretWord - updates which letters of the secret word have been revealed
 private void updateSecretWord(String l){
 List<Integer> changeBool = new ArrayList<Integer>();
  if(secretWord.contains(l)){
 // Searches through secretWord & notes down all letters that equal the user's guess
 for(int i=0; i<secretWord.length(); i++){
  if(secretWord.charAt(i) == l.charAt(0))
  changeBool.add(i);
 }
 // Changes the boolean value for those letters @ their corresponding indexes
 for(Integer idx : changeBool)
 lettersRevealed[idx] = true;
 }else{
 GuessesRemaining--;
 drawGuessesRemaining();
 }
 }
 // winSequence - when the user has correctly guessed the secret word
 private void winSequence(){
 playAgain("Well done! You guessed " + secretWord + " with " + GuessesRemaining + " guesses left!\n" +
 "Would you like to play another game of hangman?");
 }
 // GETTERS
 private String getText(){
 return textField.getText();
 }
 // SETTERS
 private void setText(final String t){
 SwingUtilities.invokeLater(
 new Runnable(){
 @Override
 public void run(){
 textField.setText(t);
 }
 }
 );
 }
 // ActionListener
 private class TextListener implements ActionListener {
 @Override
 public void actionPerformed(ActionEvent ev){
 String guess = getText();
 if(checkUserGuess(guess)) {
 updateSecretWord(guess);
 drawSecretWord();
 if(lettersGuessed.size() != 0) // No letters have been guessed by the user at the beginning
 drawLettersGuessed();
 // Checks if the user has won or lost
 if (checkIfWon())
 winSequence();
 else if (GuessesRemaining == 0)
 loseSequence();
 }
 }
 }
}

Today I wrote an implementation of Hangman (code below) that was originally written to be used on the command-line. I'm in the process of getting it to work on some simple GUI, and I've almost got it to work on a GUI, however I'm having difficulty in determining how to get the user input from the JTextField into the appropriate parts of the code (like the userGuess() invoked in the play() method).

I understand that the action listener linked to the JTextField will run on the EDT & so isn't that a separate thread from the thread of that play() is in? Do I need to send the info from the EDT thread to the main thread? I know I can get the text using .getText() but I'd like for the code to wait for the user to make a guess (i.e. block), like how it waits in the command-line when Scanner(System.in) is used.

Also, please let me know of any improvements I can make to my coding style. Thanks for your help.

 import java.awt.*;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
 import java.io.*;
 import java.util.*;
 import java.util.List;
 import javax.swing.*;
 import javax.swing.text.BadLocationException;
 import javax.swing.text.Document;
 
 
 public class Hangman {
 String[] wordList;
 String secretWord;
 Set<Character> alphabet;
 Set<Character> lettersGuessed; // letters the user has guessed
 boolean[] lettersRevealed; // determines if the letter should be revealed or not
 
 Scanner k = new Scanner(System.in);
 
 boolean keepGoing;
 boolean keepPlaying; // allows the player to play another game of hangman
 int GuessesRemaining;
 
 // GUI
 Document doc;
 JTextField textField;
 
 
 public static void main(String[] args){
 Hangman h = new Hangman();
 h.readFile("words.txt");
 h.buildGUI();
 h.play();
 }
 
 // appendMessage - appends text to the text area
 private void appendMessage(final String message){
 SwingUtilities.invokeLater(
 new Runnable(){
 @Override
 public void run(){
 try{
 doc.insertString(doc.getLength(), message, null);
 }catch(BadLocationException badLocationException){
  badLocationException.printStackTrace();
 }
 }
 }
 );
 }
 
 // buildGUI - builds the GUI
 private void buildGUI(){
 JFrame f = new JFrame("Hangman");
 
 // Text area
 JTextArea textArea = new JTextArea();
 doc = textArea.getDocument();
 textArea.setEditable(false);
 textArea.setLineWrap(true);
 textArea.setWrapStyleWord(true);
 
 JScrollPane jsp = new JScrollPane(textArea);
 
 // Text field for user to type letters in
 textField = new JTextField(10); // TODO fix the textField's size
 JButton checkButton = new JButton("Send");
 
 // Add listeners to textField & checkButton
 TextListener textListener = new TextListener();
 checkButton.addActionListener(textListener);
 textField.addActionListener(textListener);
 
 // Add everything to frame
 JPanel panel = new JPanel();
 panel.add(BorderLayout.WEST, textField);
 panel.add(BorderLayout.EAST, checkButton);
 
 f.add(BorderLayout.CENTER, jsp);
 f.add(BorderLayout.SOUTH, panel);
 
 f.setSize(300, 300);
 f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
 f.setVisible(true);
 }
 
 // checkIfWon - sees if the user has won the game
 private boolean checkIfWon(){
 for(boolean tof : lettersRevealed){
 if(!tof)
 return false;
 }
 return true;
 }
 
 // chooseSecretWord - selects a word
 private String chooseSecretWord(String[] wordList){
 return wordList[(int)(Math.random() * wordList.length)];
 }
 
 // createAlphabetSet - Creates the alphabet set that's used to ensure that the user's guess not a number nor a special character
 private void createAlphabetSet(){
 alphabet = new HashSet<Character>(26);
 for(Character c = 'a'; c<='z'; c++){
 alphabet.add(c);
 }
 }
 
 // drawSecretWord - draws the secret word with dashes & etc for user to use to guess the word with
 private void drawSecretWord(){
 StringBuilder word = new StringBuilder();
 for(int i=0; i<lettersRevealed.length; i++){
 
 if(lettersRevealed[i]){
 String s = secretWord.charAt(i) + " ";
 word.append(s);
 }else{
 word.append("_ ");
 }
 }
 appendMessage(word + "\n");
 System.out.println(word);
 }
 
 // play - Initiates a game of hangman
 public void play(){
 keepPlaying = true;
 createAlphabetSet();
 
 while(keepPlaying) {
 setUpGame();
 appendMessage("Welcome to hangman! You have 5 guesses to guess the secret word.\n");
 System.out.println("Welcome to hangman! You have 5 guesses to guess the secret word.");
 
 // user's guess
 String guess;
 while (GuessesRemaining > 0 && keepGoing) {
 drawSecretWord();
 
 // Doesn't output this at the beginning
  if(lettersGuessed.size() != 0) {
 appendMessage("Letters already guessed: ");
 System.out.print("Letters already guessed: ");
 for (Character el : lettersGuessed) {
 appendMessage(el + " ");
 System.out.print(el + " ");
 }
 appendMessage("\n");
 System.out.println();
 }
 
 guess = userGuess("Guess a letter:");
 updateSecretWord(guess);
 
 appendMessage("\n");
 System.out.println();
 
 if (checkIfWon()) {
 keepGoing = false;
 appendMessage("Well done! You guessed " + secretWord + " with " + GuessesRemaining + " guesses left!\n");
 System.out.println("Well done! You guessed " + secretWord + " with " + GuessesRemaining + " guesses left!");
 }
 }
 
 // If player runs out of guesses
 if (GuessesRemaining == 0) {
 appendMessage("Tough luck. The secret word was " + secretWord + "\n");
 System.out.println("Tough luck. The secret word was " + secretWord);
 }
 
 playAgain("Would you like to play another game of hangman? (type yes or no)");
 }
 }
 
 // playAgain - Allows the user to play another game of hangman
 private void playAgain(String message){
 appendMessage(message + "\n");
 System.out.println(message);
  String ans = k.next().toLowerCase();
 
 if(ans.equals("yes")) {
 appendMessage("Okay! Let's play another game of hangman!\n\n\n");
 System.out.println("Okay! Let's play another game of hangman!\n\n");
 }else if(ans.equals("no")){
 keepPlaying = false;
 appendMessage("Fair enough. Bye!");
 System.out.println("Fair enough. Bye!");
 }else{
 playAgain("Invalid input. Please type in yes or no: ");
 }
 }
 
 // readFile - read in wordList
 private String[] readFile(String loc){
 try {
 File f = new File(loc);
 assert f.exists() : "File doesn't exist";
 
 BufferedReader input = new BufferedReader(new FileReader(f));
 
 // read in the stuff into an arrayList here
 wordList = input.readLine().split(" ");
 
 // close the input stream
 input.close();
 }catch(IOException ioException){
 ioException.printStackTrace();
 }
 return wordList;
 }
 
 // setUpGame - sets up the variables appropriately
 private void setUpGame(){
 keepGoing = true;
 GuessesRemaining = 5;
 secretWord = chooseSecretWord(wordList);
 lettersRevealed = new boolean[secretWord.length()];
 Arrays.fill(lettersRevealed, false);
 lettersGuessed = new HashSet<Character>(26); // 26 letters in alphabet
 }
 
 // updateSecretWord - updates which letters of the secret word have been revealed
 private void updateSecretWord(String l){
 List<Integer> changeBool = new ArrayList<Integer>();
 
 if(secretWord.contains(l)){
 // Searches through secretWord & notes down all letters that equal the user's guess
 for(int i=0; i<secretWord.length(); i++){
 if(secretWord.charAt(i) == l.charAt(0))
 changeBool.add(i);
 }
 
 // Changes the boolean value for those letters @ their corresponding indexes
 for(Integer idx : changeBool)
 lettersRevealed[idx] = true;
 }else{
 GuessesRemaining--;
 appendMessage("Letter not found. You have " + GuessesRemaining + " guesses remaining.\n");
 System.out.println("Letter not found. You have " + GuessesRemaining + " guesses remaining.");
 }
 }
 
 // get input from the user
 private String userGuess(String message){
 appendMessage(message + "\n");
 System.out.println(message);
 String l = k.next().toLowerCase();
 
 if(l.length() == 0) {
 l = userGuess("Nothing has been typed. Please guess a letter:");
 }else if(l.length() > 1) {
 l = userGuess("More than one letter was typed. Please select only one letter:");
 }else if(lettersGuessed.contains(l.charAt(0))){
 l = userGuess("Letter already guessed. Please choose another letter:");
 }else if(!alphabet.contains(l.charAt(0))){
 l = userGuess("Not a letter. Please choose a letter:");
 }
 
 lettersGuessed.add(l.charAt(0));
 return l;
 }
 
 
 // GETTERS
 private String getText(){
 return textField.getText();
 }
 
 
 // SETTERS
 private void setText(final String t){
 SwingUtilities.invokeLater(
 new Runnable(){
 @Override
 public void run(){
 textField.setText(t);
 }
 }
 );
 }
 
 
 // ActionListener -- TODO need the input from the the textField to go into userGuess method somehow
 private class TextListener implements ActionListener {
 @Override
 public void actionPerformed(ActionEvent ev){
 appendMessage(getText());
 setText(null);
 }
 }
 }

Here's an implementation of Hangman that I've written that uses a basic GUI. As I am new to Java, please let me know of any improvements I can make to my coding style. Thanks for your help.

 import java.awt.*;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
 import java.io.*;
 import java.util.*;
 import java.util.List;
 import javax.swing.*;
 
 
 public class Hangman {
 String[] wordList;
 String secretWord;
 Set<Character> alphabet;
 Set<Character> lettersGuessed; // letters the user has guessed
 boolean[] lettersRevealed; // determines if the letter should be revealed or not
 
 int GuessesRemaining;
 
 // GUI
 JFrame f;
 JTextField textField;
 JLabel guessesRemainingLabel;
 JLabel lettersGuessedLabel;
 JLabel secretWordLabel;
 
 
 public static void main(String[] args){
 Hangman h = new Hangman();
 h.createAlphabetSet();
 h.readFile("words.txt");
 h.buildGUI();
 h.setUpGame();
 h.drawSecretWord();
 }
 
 // buildGUI - builds the GUI
 private void buildGUI(){
 f = new JFrame("Hangman");
 
 // JLabels
  guessesRemainingLabel = new JLabel("Guesses remaining: " + String.valueOf(GuessesRemaining));
 lettersGuessedLabel = new JLabel("Already guessed: ");
 secretWordLabel = new JLabel();
 
 // Text field for user to type letters in
 textField = new JTextField();
 JButton checkButton = new JButton("Guess");
 
 // Add listeners to textField & checkButton
 TextListener textListener = new TextListener();
 checkButton.addActionListener(textListener);
 textField.addActionListener(textListener);
 
 // Panel for all the labels
 JPanel labelPanel = new JPanel();
 labelPanel.setLayout(new BoxLayout(labelPanel, BoxLayout.PAGE_AXIS));
 labelPanel.add(guessesRemainingLabel);
 labelPanel.add(lettersGuessedLabel);
  labelPanel.add(secretWordLabel);
 
 // User panel
 JPanel userPanel = new JPanel(new BorderLayout());
 userPanel.add(BorderLayout.CENTER, textField);
 userPanel.add(BorderLayout.EAST, checkButton);
 labelPanel.add(userPanel);
 
 // Add everything to frame
 f.add(BorderLayout.CENTER, labelPanel);
 
 f.setSize(250, 100);
 f.setLocationRelativeTo(null);
 f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
 f.setVisible(true);
 }
 
 // checkIfWon - sees if the user has won the game
 private boolean checkIfWon(){
 for(boolean tof : lettersRevealed){
 if(!tof)
 return false;
 }
 return true;
 }
 
 // get input from the user
 private boolean checkUserGuess(String l){
 if(l.length() == 1 && !lettersGuessed.contains(l.charAt(0)) && alphabet.contains(l.charAt(0))) {
 setText(null);
 lettersGuessed.add(l.charAt(0));
 return true;
 }else {
 Toolkit.getDefaultToolkit().beep();
 }
 return false;
 }
 
 // chooseSecretWord - selects a word
 private String chooseSecretWord(String[] wordList){
 return wordList[(int)(Math.random() * wordList.length)];
 }
 
 // createAlphabetSet - Creates the alphabet set that's used to ensure that the user's guess not a number nor a special character
 private void createAlphabetSet(){
 alphabet = new HashSet<Character>(26);
 for(Character c = 'a'; c<='z'; c++){
 alphabet.add(c);
 }
 }
 
 // drawGuessesRemaining - Outputs the guesses remaining
 void drawGuessesRemaining(){
 final String guessesMessage = "Guesses remaining: " + String.valueOf(GuessesRemaining);
 SwingUtilities.invokeLater(
 new Runnable(){
 @Override
 public void run(){
 guessesRemainingLabel.setText(guessesMessage);
 guessesRemainingLabel.setAlignmentX(Component.LEFT_ALIGNMENT);
 }
 }
 );
 }
 
 // drawLettersGuessed - Outputs the letters guessed
 void drawLettersGuessed(){
 StringBuilder lettersBuilder = new StringBuilder();
 for (Character el : lettersGuessed) {
 String s = el + " ";
 lettersBuilder.append(s);
 }
 
 final String letters = lettersBuilder.toString();
 SwingUtilities.invokeLater(
 new Runnable() {
 @Override
 public void run() {
 lettersGuessedLabel.setText("Already guessed: " + letters);
 }
 }
 );
 }
 
 // drawSecretWord - draws the secret word with dashes & etc for user to use to guess the word with
 private void drawSecretWord(){
 StringBuilder word = new StringBuilder();
 for(int i=0; i<lettersRevealed.length; i++){
 
 if(lettersRevealed[i]){
 String s = secretWord.charAt(i) + " ";
 word.append(s);
 }else{
 word.append("_ ");
 }
 }
 
 final String w = word.toString();
 SwingUtilities.invokeLater(
 new Runnable(){
 @Override
 public void run(){
 secretWordLabel.setText(w);
 }
 }
 );
 }
 
 // loseSequence - when the the user runs out of guesses
  private void loseSequence(){
 for(int i=0; i<lettersRevealed.length; i++)
 lettersRevealed[i] = true;
 drawSecretWord();
 playAgain("Tough luck. The secret word was " + secretWord + ".\nWould you like to play another game of hangman?");
 }
 
 // playAgain - Allows the user to play another game of hangman
 private void playAgain(String message){
 int ans = JOptionPane.showConfirmDialog(f, message,
 "Play again?", JOptionPane.YES_NO_OPTION, JOptionPane.PLAIN_MESSAGE);
 
 if(ans == JOptionPane.YES_OPTION) {
 setUpGame();
 }else {
 System.exit(0);
 }
 }
 
 // readFile - read in wordList
 private String[] readFile(String loc){
 try {
 File f = new File(loc);
 assert f.exists() : "File doesn't exist";
 
 BufferedReader input = new BufferedReader(new FileReader(f));
 
 // read in the stuff into an arrayList here
 wordList = input.readLine().split(" ");
 
 // close the input stream
 input.close();
 }catch(IOException ioException){
 ioException.printStackTrace();
 }
 return wordList;
 }
 
 // setUpGame - sets up the variables appropriately
 private void setUpGame(){
 GuessesRemaining = 5;
 secretWord = chooseSecretWord(wordList);
 lettersRevealed = new boolean[secretWord.length()];
 Arrays.fill(lettersRevealed, false);
 lettersGuessed = new HashSet<Character>(26); // 26 letters in alphabet
 
 drawSecretWord();
 drawLettersGuessed();
 drawGuessesRemaining();
 }
 
 // updateSecretWord - updates which letters of the secret word have been revealed
 private void updateSecretWord(String l){
 List<Integer> changeBool = new ArrayList<Integer>();
 
 if(secretWord.contains(l)){
 // Searches through secretWord & notes down all letters that equal the user's guess
 for(int i=0; i<secretWord.length(); i++){
 if(secretWord.charAt(i) == l.charAt(0))
 changeBool.add(i);
 }
 
 // Changes the boolean value for those letters @ their corresponding indexes
 for(Integer idx : changeBool)
 lettersRevealed[idx] = true;
 }else{
 GuessesRemaining--;
 drawGuessesRemaining();
 }
 }
 
 // winSequence - when the user has correctly guessed the secret word
 private void winSequence(){
 playAgain("Well done! You guessed " + secretWord + " with " + GuessesRemaining + " guesses left!\n" +
 "Would you like to play another game of hangman?");
 }
 
 
 
 
 // GETTERS
 private String getText(){
 return textField.getText();
 }
 
 
 // SETTERS
 private void setText(final String t){
 SwingUtilities.invokeLater(
 new Runnable(){
 @Override
 public void run(){
 textField.setText(t);
 }
 }
 );
 }
 
 
 // ActionListener
 private class TextListener implements ActionListener {
 @Override
 public void actionPerformed(ActionEvent ev){
 String guess = getText();
 
 if(checkUserGuess(guess)) {
 updateSecretWord(guess);
  drawSecretWord();
 
 if(lettersGuessed.size() != 0) // No letters have been guessed by the user at the beginning
 drawLettersGuessed();
 
 // Checks if the user has won or lost
 if (checkIfWon())
 winSequence();
 else if (GuessesRemaining == 0)
 loseSequence();
 }
 }
 }
 }