Constantly updating and changing text in a JLabel

Question

So I'm new to Java and learning to use Swing, and I'm currently working on a project that's assigned to me by my lecturer. It's some stupid version of some kind of bruteforcer that tries to guess a word typed by the user.

Instead of printing all the guessed words, I want to have them shown in a JLabel that's on my UI. (This would constantly spam different combinations.)

But the problem is: It only shows a guessed word after my program has finished running (so it found the word).

I've searched around and looked for an update method, but I can't seem to find where to actually use testField.setVisible(true);.

Program code:

package gui;
import static com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type.Int;
import java.util.Random; 
import java.util.Arrays;
import java.util.*;

public class bruteforcePanel extends javax.swing.JPanel {

    String[] Alphabet = {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"};
    //String[] Alphabet = {"a"};
    boolean startGuessing = false;
    String pass;
    String[] word;
    String[] javaStuff;
    List<String> guessedWord = new ArrayList<String>();
    int amountOfGuesses;
    String labelGuess;

    private void startBruteforce(java.awt.event.ActionEvent evt) {                                 

        pass = textBoxPassword.getText();
        //this.testField.setText(pass);
        word = pass.split("");
        //System.out.println(Arrays.toString(word));
        startGuessing = true;
        while(startGuessing == true) {
            for (String i : word) {
                Random r=new Random();
                int randomNumber=r. nextInt(Alphabet. length);
                String chosenLetter = Alphabet[randomNumber];
                guessedWord.add(chosenLetter);
            }
            System.out.println(guessedWord);
            labelGuess = String.join("", guessedWord);
            this.testField.setText(labelGuess);
            if (guessedWord.equals(Arrays.asList(word))) {
                startGuessing = false;
                System.out.println(amountOfGuesses);
            } else {
               guessedWord.clear(); 
               amountOfGuesses += 1;
            }

        }
    }                                

    // Variables declaration - do not modify                     
    private javax.swing.JButton bruteforceButton;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JLabel testField;
    private javax.swing.JTextField textBoxPassword;
    // End of variables declaration                   
}

Code from JPanel: (comes before the private void startBruteforce(java.awt.event.ActionEvent evt) {})

    public bruteforcePanel() {
        initComponents();
    }
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jPanel1 = new javax.swing.JPanel();
        textBoxPassword = new javax.swing.JTextField();
        bruteforceButton = new javax.swing.JButton();
        jLabel1 = new javax.swing.JLabel();
        testField = new javax.swing.JLabel();

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 146, Short.MAX_VALUE)
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 205, Short.MAX_VALUE)
        );

        bruteforceButton.setText("Bruteforce");
        bruteforceButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                startBruteforce(evt);
            }
        });

        jLabel1.setText("Word:");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
        this.setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addGap(151, 151, 151)
                        .addComponent(bruteforceButton))
                    .addGroup(layout.createSequentialGroup()
                        .addGap(15, 15, 15)
                        .addComponent(jLabel1)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addComponent(testField)))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addContainerGap())
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap(95, Short.MAX_VALUE)
                .addComponent(textBoxPassword, javax.swing.GroupLayout.PREFERRED_SIZE, 215, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(90, 90, 90))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(29, 29, 29)
                .addComponent(textBoxPassword, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addGap(36, 36, 36)
                        .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                        .addContainerGap())
                    .addGroup(layout.createSequentialGroup()
                        .addGap(18, 18, 18)
                        .addComponent(bruteforceButton)
                        .addGap(9, 9, 9)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                            .addComponent(jLabel1)
                            .addComponent(testField))
                        .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))))
        );
    }// </editor-fold> 

So like I said, I want my results to "spam" in the label.

Answer 1

1. You don't want to use a JLabel for this task but a JTextArea instead
2. You need to stop using bad words (even in the code)
3. Follow Java naming conventions and use them consistently.
   • firstWordLowerCaseVariable
   • firstWordLowerCaseMethod()
   • FirstWordUpperCaseClass
   • ALL_WORDS_UPPER_CASE_CONSTANT
4. For your UI to update after a new result is done, you're going to need a Swing Timer, for example: Creating an animated 4x4 grid in Java and jLabel won't show

5. And you'll need to call JPanel#revalidate() and JPanel#repaint() methods (in that order) inside the ActionListener of the Timer and you'll probably need to wrap the JTextArea inside a JScrollPane as well.

   And you need to use a Swing Timer and not a while or any other kind of loop, as they block the EDT preventing it from updating until the loop is done.