Converting short to byte[] in Java

1. Introduction

Converting a short value to a byte[] array is a common task in Java programming, especially when dealing with binary data or network communication.

In this tutorial, we’ll explore various approaches to achieve this conversion efficiently.

2. Using ByteBuffer Class (Java NIO)

The Java NIO package provides the ByteBuffer class, which simplifies the conversion of primitive data types into byte arrays. Let’s take a look at how we can use it to convert a short value to a byte[] array:

short shortValue = 12345;
byte[] expectedByteArray = {48, 57};
@Test
public void givenShort_whenUsingByteBuffer_thenConvertToByteArray() {
    ByteBuffer buffer = ByteBuffer.allocate(2);
    buffer.putShort(shortValue);
    byte[] byteArray = buffer.array();
    assertArrayEquals(expectedByteArray, byteArray);
}

In this method, we use the allocate() method to allocate a ByteBuffer with a capacity of 2 bytes to accommodate shortValue. Next, we utilize the putShort() method to write the binary representation of shortValue into the buffer object. This operation results in the buffer containing the byte representation of shortValue.

We then extract the byte array named byteArray from the buffer using the array() method, which retrieves the byte array corresponding to the stored short value.

Finally, we assert that byteArray matches the expectedByteArray using the assertArrayEquals() method, ensuring the accuracy of the conversion process.

3. Using DataOutputStream Class

Another approach is to utilize the DataOutputStream class, which provides an efficient way to accomplish the conversion process. Let’s see how we can implement this approach:

@Test
public void givenShort_whenUsingDataOutputStream_thenConvertToByteArray() throws IOException {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    DataOutputStream dos = new DataOutputStream(baos);
    dos.writeShort(shortValue);
    dos.close();
    byte[] byteArray = baos.toByteArray();
    assertArrayEquals(expectedByteArray, byteArray);
}

In this test method, we first utilize the DataOutputStream class to write the short value to a ByteArrayOutputStream object named baos.

Moreover, we invoke the writeShort() method to serialize shortValue into two bytes that represent its binary form. Subsequently, we retrieve the resulting byte array from baos using the toByteArray() method.

4. Manual Bit Manipulation

This approach effectively converts a short value into a byte array by explicitly manipulating the bits of the short value to isolate and store the most significant byte (MSB) and least significant byte (LSB) components in the respective positions of the byte array.

Let’s delve into the implementation:

@Test
public void givenShort_whenUsingManualBitManipulation_thenConvertToByteArray() {
    byte[] byteArray = new byte[2];
    byteArray[0] = (byte) (shortValue >> 8);
    byteArray[1] = (byte) shortValue;
    assertArrayEquals(expectedByteArray, byteArray);
}

Here, we first extract the MSB by shifting shortValue right by 8 bits (shortValue >> 8), and the result is cast to a byte to store in byteArray[0]. Similarly, the least significant byte (LSB) of shortValue is obtained by casting it directly to a byte and then storing it in byteArray[1].

5. Conclusion

In conclusion, mastering the conversion of a short value to a byte[] array in Java is essential for various tasks. Hence, we explored different approaches, such as using ByteBuffer from Java NIO, manual bit manipulation, or leveraging DataOutputStream.

As always, the complete code samples for this article can be found over on GitHub.