Read/write file contents in java (example/InputStreamReader/OutputStreamWriter)

1. Read & Write file in java using InputStreamReader & OutputStreamWriter class.
2. We will write contents to a file using OutputStreamWriter class in java.
3. We will read contents from file using InputStreamReader class in java.
4. InputStreamReader and OutputStreamWriter is character based reader and writer.

1. InputStreamReader class:

• InputStreamReader converts bytes to characters using specified charset.
• Read methods InputStreamReader class are as follows:

2. OutputStreamWriter class:

• OutputStreamWriter converts characters to bytes using specified charset.
• Write methods of OutputStreamWriter class are as follows:

OutputStreamWriter will act as character to byte encoder and InputStreamReader will act as byte to character decoder.

3. Read & write file in java (InputStreamReader/OutputStreamWriter)

package org.learn.io;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;

public class SteamReaderWriter {
    public static void main(String[] args) throws IOException {
        //Write contents to file using input stream writer
        writeUsingStreamWriter();
        //Read contents from file using input stream reader
        readUsingStreamReader();
    }

    private static void writeUsingStreamWriter() throws IOException {
        String newLine = System.getProperty("line.separator");
        try (FileOutputStream fileStream = new FileOutputStream(
                new File("sampleFile.txt"));
             OutputStreamWriter writer = new OutputStreamWriter(fileStream)) {

            System.out.println("1. Start Writing file using OutputStreamWriter:");

            writer.write("Soccer");
            System.out.println("Written \"Soccer\" to a file");
            writer.write(newLine);
            writer.write("Tennis");
            System.out.println("Written \"Tennis\" to a file");
            writer.write(newLine);
            writer.write("Badminton");
            System.out.println("Written \"Badminton\" to a file");
            writer.write(newLine);
            writer.write("Hockey");
            System.out.println("Written \"Hockey\" to a file");
            writer.write(newLine);

            System.out.println("2. End Writing file using OutputStreamWriter");
            System.out.println();
        }
    }

    private static void readUsingStreamReader() throws IOException {
        try (FileInputStream fileStream = new FileInputStream(
                new File("sampleFile.txt"));
             InputStreamReader reader = new InputStreamReader(fileStream)) {

            System.out.println("3. Start Reading the file using InputStreamReader:");
            int character;
            while ((character = reader.read()) != -1) {
                System.out.print((char) character);
            }
            System.out.println("4. End Reading the file using InputStreamReader");
        }
    }
}

The content of sampleFile.txt is as follows:

4. O/P:Read & write file in java – InputStreamReader & OutputStreamWriter

1. Start Writing file using OutputStreamWriter:
Written "Soccer" to a file
Written "Tennis" to a file
Written "Badminton" to a file
Written "Hockey" to a file
2. End Writing file using OutputStreamWriter

3. Start Reading the file using InputStreamReader:
Soccer
Tennis
Badminton
Hockey
4. End Reading the file using InputStreamReader