How to read file using Files.newBufferedReader?

By Wayan in Core API, IO 1 Comment

In the snippet below you’ll learn to open file for reading using Files.newBufferedReader() method in JDK 7. This method returns a java.io.BufferedReader which makes a backward compatibility with the old I/O system in Java.

To read a file you’ll need to provide a Path and the Charset to the newBufferedReader() method arguments.

package org.kodejava.io;

import java.io.BufferedReader;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

public class FilesNewBufferedReader {
    public static void main(String[] args) {
        Path logFile = Paths.get("app.log");
        try (BufferedReader reader =
                     Files.newBufferedReader(logFile, StandardCharsets.UTF_8)) {
            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println(line);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

How do I create a URL object?

By Wayan in Core API, Networking 0 Comment 
package org.kodejava.net;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.nio.charset.StandardCharsets;

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(), StandardCharsets.UTF_8));

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

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

How do I read or download web page content?

By Wayan in Core API, Networking 0 Comment

You want to create a program that read a webpage content of a website page. The example below use the URL class to create a connection to the website. You create a new URL object and pass the URL information of a page. After the object created you can open a stream connection using the openStream() method of the URL object.

Next, you can read the stream using the BufferedReader object. This reader allows you to read line by line from the stream. To write it to a file create a writer using the BufferedWriter object and specify the file name where the downloaded page will be stored.

When all the content are read from the stream and stored in a file close the BufferedReader object and the BufferedWriter object at the end of your program.

package org.kodejava.net;

import java.io.*;
import java.net.URL;
import java.nio.charset.StandardCharsets;

public class UrlReadPageDemo {
    public static void main(String[] args) {
        try {
            URL url = new URL("https://kodejava.org");

            BufferedReader reader = new BufferedReader(
                    new InputStreamReader(url.openStream(), StandardCharsets.UTF_8));
            BufferedWriter writer = new BufferedWriter(
                    new FileWriter("data.html", StandardCharsets.UTF_8));

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

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

How do I read a text file using BufferedReader?

By Wayan in Core API, IO 0 Comment

The code snippet below is an example of how to read a text file using BufferedReader class from the java.io package. This snippet read a text file called README.md and print out its content.

To create an instance of java.io.BufferedReader we do the following steps:

File file = new File("README.md");
FileReader fileReader = new FileReader(file));
BufferedReader bufferedReader = new BufferedReader(fileReader);

Let’s see the complete code snippet.

package org.kodejava.io;

import java.io.*;

public class ReadTextFileExample {
    private static final String LINE_SEPARATOR = System.getProperty("line.separator");

    public static void main(String[] args) {
        File file = new File("README.md");
        try (BufferedReader reader = new BufferedReader(new FileReader(file))) {
            StringBuilder contents = new StringBuilder();
            String text;
            while ((text = reader.readLine()) != null) {
                contents.append(text).append(LINE_SEPARATOR);
            }

            System.out.println(contents.toString());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

You can also try to use the following example to read a file, How do I read text file content line by line using commons-io?. To create and write a text file see the following example: How do I create and write data into text file?.