Java IO-DataOutputStream

The DataOutputStream class in Java IO provides an efficient and convenient way to write primitive data types to an output stream. It works in conjunction with the DataInputStream class to read the same data types from an input stream.

Features

• Allows writing primitive data types (boolean, byte, char, short, int, long, float, double) and strings.
• Provides methods to write arrays of the supported data types.
• Supports writing binary data by converting primitive data types to a sequence of bytes.
• Handles endianness while writing multibyte data types (short, int, long, float, double).

Usage

To use DataOutputStream in your Java program, follow these steps:

1. Create an OutputStream

First, you need to create an output stream using any of the available implementations, such as FileOutputStream, ByteArrayOutputStream, or Socket.getOutputStream(). For example:

OutputStream outputStream = new FileOutputStream("output.txt");

2. Create a DataOutputStream

Next, create a DataOutputStream object by passing the output stream as a parameter to its constructor. For example:

DataOutputStream dataOutputStream = new DataOutputStream(outputStream);

3. Write data

Now, you can use various write methods provided by DataOutputStream to write data to the output stream. For example, to write a string and an integer:

dataOutputStream.writeUTF("Hello, World!");
dataOutputStream.writeInt(42);

4. Close the stream

After writing the data, it is important to close the stream to release any system resources associated with it. The DataOutputStream class automatically closes the underlying output stream when it is closed. For example:

dataOutputStream.close();

Example

Here's a complete example that demonstrates writing primitive data types to a file using DataOutputStream:

import java.io.DataOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;

public class DataOutputStreamExample {
    public static void main(String[] args) {
        try {
            OutputStream outputStream = new FileOutputStream("output.txt");
            DataOutputStream dataOutputStream = new DataOutputStream(outputStream);
            
            dataOutputStream.writeInt(42);
            dataOutputStream.writeDouble(3.14);
            dataOutputStream.writeUTF("Hello, World!");
            
            dataOutputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

This creates a file named "output.txt" with the values 42, 3.14, and "Hello, World!" written to it.

Conclusion

DataOutputStream in Java IO provides a convenient way to write primitive data types and strings to an output stream. It is particularly useful when dealing with binary formats or when sending data over a network. The provided example should help you get started with writing data using DataOutputStream.