How do I read text file into JTextArea?

Using the read(Reader in, Object desc) method inherited from the JTextComponent allow us to populate a JTextArea with text content from a file. This example will show you how to do it.

In this example we use an InputStreamReader to read a file from our application resource. You could use other Reader implementation such as the FileReader to read to content of a file. Let’s see the code below.

package org.kodejava.example.swing;

import javax.swing.*;
import java.awt.*;
import java.io.IOException;
import java.io.InputStreamReader;

public class PopulateTextAreaFromFile extends JFrame {
    public PopulateTextAreaFromFile() {
        initialize();
    }

    private void initialize() {
        setSize(300, 300);
        setTitle("Populate JTextArea from File");
        setLayout(new BorderLayout());
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        JTextArea textArea = new JTextArea();
        JScrollPane scrollPane = new JScrollPane(textArea);
        try {
            //
            // Read some text from the resource file to display in
            // the JTextArea.
            //
            textArea.read(new InputStreamReader(
                    getClass().getResourceAsStream("/data.txt")),
                    null);
        } catch (IOException e) {
            e.printStackTrace();
        }

        getContentPane().add(scrollPane, BorderLayout.CENTER);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new PopulateTextAreaFromFile().setVisible(true);
            }
        });
    }
}

How do I create a URL object?

package org.kodejava.example.network;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;

public class URLDemo {
    public static void main(String[] args) {
        try {
            // Creating a url object by specifying each parameter separately, including
            // the protocol, hostname, port number, and the page name
            URL url = new URL("https", "kodejava.org", 443, "/index.php");

            // We can also specify the address in a single line
            url = new URL("https://kodejava.org:443/index.php");

            BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream()));

            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println(line);
            }

            reader.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}