How to Convert an Integer to a Byte Array in Java

How can I convert an integer to a byte array in Java?

int number = 1695609641; String hex = Integer.toHexString(number);

In Java, converting an integer to a byte array can be accomplished using bit manipulation. Below are detailed steps to achieve this conversion, along with an example implementation.

int number = 1695609641;
byte[] bytearray = new byte[4];
bytearray[0] = (byte) (number >> 24); // First byte
bytearray[1] = (byte) (number >> 16); // Second byte
bytearray[2] = (byte) (number >> 8);  // Third byte
bytearray[3] = (byte) number;         // Fourth byte

System.out.println(Arrays.toString(bytearray)); // Output: [-107, 81, 3, 41]

Causes

• In Java, integers are represented in 4 bytes (32 bits). Each byte can hold values from -128 to 127, while integers can store both positive and negative values.
• The conversion process involves extracting each byte from the integer using bitwise operations.

Solutions

• Use the bitwise shift (`>>`) and bitwise AND (`&`) operators to extract each byte from the integer.
• Store these bytes in a byte array.

Mistake: Not using bitwise operations correctly to extract bytes from the integer.

Solution: Remember to shift the bits correctly before applying the AND operation.

Mistake: Misunderstanding the byte representation of integers, leading to unexpected results.

Solution: Use casting to convert integers to bytes without losing information.