Streams
ByteStream and CharacterStream
Byte Stream - Writing to a File
For byte streams, we use FileOutputStream
import java.io.FileOutputStream;
import java.io.IOException;
public class ByteWrite {
public static void main(String[] args) {
try {
FileOutputStream out =
new FileOutputStream("bytefile.txt");
String data = "Hello Java";
byte[] bytes = data.getBytes();
//It converts the string into a sequence of bytes.
out.write(bytes);
out.close();
System.out.println("Data written successfully.");
} catch (IOException e) {
System.out.println("Error: " + e.getMessage());
}
}
}
For Reading bytes, we use FileInputStream
import java.io.FileInputStream;
import java.io.IOException;
public class ByteRead {
public static void main(String[] args) {
try {
FileInputStream in =
new FileInputStream("bytefile.txt");
int data;
while ((data = in.read()) != -1) {
//Keep reading until there are no more bytes.
//reads one byte at a time.
//The value -1 means that the end of the file has been reached.
System.out.print((char) data);
//only because our file contains text and we want to display the byte as a character.
}
in.close();
} catch (IOException e) {
System.out.println("Error: " + e.getMessage());
}
}
}
Character Stream - Writing to a File
For character streams, we can use FileWriter
import java.io.FileWriter;
import java.io.IOException;
public class CharacterWrite {
public static void main(String[] args) {
try {
FileWriter writer =
new FileWriter("characterfile.txt");
writer.write("Hello Java");
writer.write("\n");
writer.write("This is a character stream.");
writer.close();
System.out.println("Data written successfully.");
} catch (IOException e) {
System.out.println("Error: " + e.getMessage());
}
}
}
Character Stream - Reading From a File
For reading characters, we can use FileReader
import java.io.FileReader;
import java.io.IOException;
public class CharacterRead {
public static void main(String[] args) {
try {
FileReader reader =
new FileReader("characterfile.txt");
int data;
while ((data = reader.read()) != -1) {
System.out.print((char) data);
}
reader.close();
} catch (IOException e) {
System.out.println("Error: " + e.getMessage());
}
}
}
Important Difference in the Programs
Byte Stream
Character Stream
Copying an Image: example
Here, byte stream is used not a character stream
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
public class CopyImage {
public static void main(String[] args) {
try {
FileInputStream in =
new FileInputStream("photo.jpg");
FileOutputStream out =
new FileOutputStream("copy.jpg");
int data;
while ((data = in.read()) != -1) {
out.write(data);
}
in.close();
out.close();
System.out.println("Image copied successfully.");
} catch (IOException e) {
System.out.println("Error: " + e.getMessage());
}
}
}
Note: Java needs a special value to indicate end of file A char cannot represent -1, so the method returns an int. After checking for EOF, the value is treated as a character.