JProgressBar and Status Indicators - potatoscript/JavaSwing GitHub Wiki

📑 JProgressBar and Status Indicators in Java Swing 🚦

📝 What is JProgressBar?

In Java Swing, the JProgressBar is a component that visually displays the progress of a task. It is commonly used to show the completion of long-running operations like file downloads, data processing, or any task that requires feedback to the user.

Key Features:

  • Visual Progress: Shows progress as a bar that fills up as a task progresses.
  • Indeterminate Mode: Can be used to show that an operation is in progress without knowing the exact progress.
  • Customizable: You can customize the color, size, and other properties to fit your application's style.

✅ How Does JProgressBar Work?

  • Determinate Mode: Displays progress as a percentage of completion. Requires updates to the progress value.
  • Indeterminate Mode: Displays an infinite loading animation. Useful when the total progress is unknown.

📚 Step 1: Simple JProgressBar Example

Let's create a basic JProgressBar in determinate mode that updates as a task progresses.

📝 Example: Basic JProgressBar

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

public class JProgressBarExample {
    public static void main(String[] args) {
        // Set up the frame
        JFrame frame = new JFrame("JProgressBar Example");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(300, 200);
        frame.setLayout(new BorderLayout());

        // Create a JProgressBar (from 0 to 100)
        JProgressBar progressBar = new JProgressBar(0, 100);
        progressBar.setValue(0);
        progressBar.setStringPainted(true); // Display the percentage
        frame.add(progressBar, BorderLayout.CENTER);

        // Simulate a task with progress
        new Thread(() -> {
            for (int i = 0; i <= 100; i++) {
                try {
                    Thread.sleep(50); // Simulate work
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                progressBar.setValue(i); // Update progress bar
            }
        }).start();

        // Display the frame
        frame.setVisible(true);
    }
}

🎨 Explanation

  • JProgressBar(0, 100): Initializes the progress bar with a range from 0 to 100.
  • setValue(): Updates the progress of the task by setting the value.
  • setStringPainted(true): Displays the current percentage on the progress bar.

👩‍🎨 Output:

You will see a progress bar that starts from 0 and fills up to 100% over time, simulating the progress of a task. The percentage will be displayed on the bar as it progresses.

📚 Step 2: Indeterminate Mode

In some cases, you may not know the exact progress of a task (e.g., downloading data), and you can use indeterminate mode to show that the task is ongoing.

📝 Example: Indeterminate JProgressBar

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

public class IndeterminateProgressBarExample {
    public static void main(String[] args) {
        // Set up the frame
        JFrame frame = new JFrame("Indeterminate ProgressBar Example");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(300, 200);
        frame.setLayout(new BorderLayout());

        // Create a JProgressBar in indeterminate mode
        JProgressBar progressBar = new JProgressBar();
        progressBar.setIndeterminate(true); // Set the progress bar to indeterminate mode
        frame.add(progressBar, BorderLayout.CENTER);

        // Simulate a task with unknown progress (indeterminate)
        new Thread(() -> {
            try {
                Thread.sleep(5000); // Simulate a long-running task
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            // After the task completes, hide the progress bar
            progressBar.setIndeterminate(false);
            JOptionPane.showMessageDialog(frame, "Task Completed!");
        }).start();

        // Display the frame
        frame.setVisible(true);
    }
}

🎨 Explanation

  • setIndeterminate(true): Sets the progress bar to indeterminate mode. This is useful when you don't know how long the task will take.
  • Thread.sleep(5000): Simulates a long-running task by pausing the thread for 5 seconds. After the task finishes, the progress bar is set back to normal.

👩‍🎨 Output:

The progress bar will show an animated "loading" effect, and after 5 seconds, a message box will appear to indicate that the task has been completed.

📚 Step 3: Customizing JProgressBar

You can customize the appearance of the JProgressBar to better fit the style of your application.

Customizations:

  • Background Color: Change the background color of the progress bar.
  • Foreground Color: Change the color of the progress fill.
  • Size: Adjust the height and width of the progress bar.
  • Custom Paint: Draw custom designs on the progress bar.

📝 Example: Customizing JProgressBar

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

public class CustomizedProgressBarExample {
    public static void main(String[] args) {
        // Set up the frame
        JFrame frame = new JFrame("Customized ProgressBar Example");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(300, 200);
        frame.setLayout(new BorderLayout());

        // Create a customized JProgressBar (from 0 to 100)
        JProgressBar progressBar = new JProgressBar(0, 100);
        progressBar.setValue(0);
        progressBar.setStringPainted(true); // Display percentage
        progressBar.setBackground(Color.DARK_GRAY); // Set background color
        progressBar.setForeground(Color.GREEN); // Set progress color

        // Set a custom height for the progress bar
        progressBar.setPreferredSize(new Dimension(300, 30));
        frame.add(progressBar, BorderLayout.CENTER);

        // Simulate a task with progress
        new Thread(() -> {
            for (int i = 0; i <= 100; i++) {
                try {
                    Thread.sleep(50); // Simulate work
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                progressBar.setValue(i); // Update progress bar
            }
        }).start();

        // Display the frame
        frame.setVisible(true);
    }
}

🎨 Explanation

  • setBackground(Color.DARK_GRAY): Sets the background color of the progress bar.
  • setForeground(Color.GREEN): Sets the color of the progress fill (the progress indicator).
  • setPreferredSize(new Dimension(300, 30)): Customizes the size of the progress bar.

👩‍🎨 Output:

You will see a progress bar with a dark gray background and a green fill, giving it a more customized and polished appearance.

📚 Step 4: Using JProgressBar with Status Indicators

JProgressBar can be integrated with status indicators to provide users with more information. For instance, you can show the status of a task along with the progress.

📝 Example: JProgressBar with Status Message

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

public class ProgressBarWithStatusExample {
    public static void main(String[] args) {
        // Set up the frame
        JFrame frame = new JFrame("ProgressBar with Status Example");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(300, 200);
        frame.setLayout(new BorderLayout());

        // Create a JProgressBar (from 0 to 100)
        JProgressBar progressBar = new JProgressBar(0, 100);
        progressBar.setValue(0);
        progressBar.setStringPainted(true); // Display percentage
        frame.add(progressBar, BorderLayout.CENTER);

        // Create a label to show the status
        JLabel statusLabel = new JLabel("Starting task...", JLabel.CENTER);
        frame.add(statusLabel, BorderLayout.SOUTH);

        // Simulate a task with progress
        new Thread(() -> {
            for (int i = 0; i <= 100; i++) {
                try {
                    Thread.sleep(50); // Simulate work
                    statusLabel.setText("Progress: " + i + "%"); // Update status message
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                progressBar.setValue(i); // Update progress bar
            }
            statusLabel.setText("Task Completed!"); // Final status
        }).start();

        // Display the frame
        frame.setVisible(true);
    }
}

🎨 Explanation

  • Status Label: A JLabel is used to display the current status of the task.
  • statusLabel.setText("Progress: " + i + "%"): Updates the status message with the current progress.
  • JProgressBar and JLabel: Work together to provide both visual and textual feedback to the user.

👩‍🎨 Output:

The progress bar will show the progress, and the status message will change as the task progresses, providing more information to the user.