JProgressBar

✅ Java Swing JProgressBar – Full Guide

JProgressBar is a Swing component that visually displays progress for tasks like downloading, uploading, or processing.

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🔧 Common Properties & Methods

Method / Property	Description
setMinimum(int)	Set minimum progress value (default 0)
setMaximum(int)	Set maximum progress value (default 100)
setValue(int)	Set current progress value
getValue()	Get current progress value
setStringPainted(true)	Show progress percentage as a string
setIndeterminate(true)	Show infinite progress (e.g., loading animation)
setOrientation(...)	Horizontal/Vertical (rarely used)

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✅ Basic Example: Progress Bar with Manual Update

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class ProgressBarExample {
    public static void main(String[] args) {
        JFrame frame = new JFrame("JProgressBar Example");
        frame.setSize(300, 150);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLayout(new FlowLayout());

        JProgressBar progressBar = new JProgressBar(0, 100);
        progressBar.setValue(0);
        progressBar.setStringPainted(true);

        JButton button = new JButton("Start");

        button.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                // Simulate loading in a separate thread
                new Thread(() -> {
                    for (int i = 0; i <= 100; i++) {
                        try {
                            Thread.sleep(50); // Simulate work
                        } catch (InterruptedException ex) {
                            ex.printStackTrace();
                        }
                        progressBar.setValue(i);
                    }
                }).start();
            }
        });

        frame.add(progressBar);
        frame.add(button);
        frame.setVisible(true);
    }
}

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🌀 Optional: Indeterminate Mode (Loading...)

JProgressBar progressBar = new JProgressBar();
progressBar.setIndeterminate(true);  // Shows an animated "in-progress" bar

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🧠 Notes

• Always update JProgressBar from the Event Dispatch Thread (EDT) or use SwingWorker for background tasks.

• Use setStringPainted(true) to display percentage.

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Would you like an example with file upload simulation or one using SwingWorker for real background tasks?