Java how to Convert Bytes to Hex?

In this section, we will learn different approaches to convert bytes to hexadecimal in Java.

Convert Bytes to Hex

There are the following ways to convert bytes to hexadecimal:

Using Integer.toHexString() Method
Using String.format() Method
Using Byte Operation

Using Integer.toHexString() Method

It is a built-in function of the java.lang.Integer class.

Syntax:

The function accepts a single parameter of type int num that is to be converted into hexadecimal. It returns the converted hexadecimal string (base 16) of the given number.

Note: The function does not accept numbers as strings and double or floating-point numbers.

For example, if we provide 11 as input, it returns b which is equivalent hexadecimal of 11.

Java Programs to Convert Byte to Hexadecimal

ByteToHex1.java

public class ByteToHex1
{
public static void main(String args[]) 
{
byte num = (byte)4556;
System.out.println("Byte = "+num);
int hex = num & 0xFF;
System.out.println("Hexadecimal Equivalent= "+Integer.toHexString(hex));
}
}

Output:

Byte = -52
Hexadecimal Equivalent= cc

Let's see another approach.

ByteToHex2.java

import java.lang.Math;
public class ByteToHex2
{
// driver code
public static void main(String args[])
{
int num1 = 212;
// returns the string representation of the unsigned int value
// represented by the argument in binary (base 2)
System.out.println("Hexadecimal string is: " + Integer.toHexString(num1));
int num2 = 34;
System.out.println("Hexadecimal string is: " + Integer.toHexString(num2));
int num3 = -20;
System.out.println("Hexadecimal string is: " + Integer.toHexString(num3));
}
}

Output:

Hexadecimal string is: d4
Hexadecimal string is: 22
Hexadecimal string is: ffffffec

Convert Byte Array to Hexadecimal

We can also convert bytes array to hexadecimal. The following Java program demonstrates the same.

ByteToHex3.java

public class ByteToHex3
{
//driver code
public static void main(String args[])
{
byte[] byteArray = {0, 9, 3, -1, 5, 8, -2};
StringBuilder sb = new StringBuilder();
for (byte b : byteArray) 
{
sb.append(String.format("%02X ", b));
}
System.out.println(sb.toString());
}
}

Output:

00 09 03 FF 05 08 FE

Using String.format() Method

In the following Java program, we have defined an array of type byte. After that, defined a loop that iterates over the byte array. In order to convert the byte array to a hex value, we have used the function String.format(). Inside the function, we have passed %02X that prints two places of hexadecimal (X) value and the same store in the variable str.

Syntax:

The method accepts two parameters:

format: It is the format of the string.

args: Arguments for the format string. It may be zero or more.

It returns the formatted string. It throws NullPointerException if the format is null and throws IllegalFormatException if the format is illegal or incompatible.

It is a very slow process to convert the byte array to hexadecimal.

ByteToHex4.java

public class ByteToHex4
{
public static void main(String args[]) 
{
byte[] bytes = {11, 5, 19, 56};
for (byte b : bytes) 
{
String str = String.format("%02X", b);
System.out.print(str+"\t");
}
}
}

Output:

0B	05	13	38

Using Byte Operation

ByteToHex5.java

public class ByteToHex5
{
//defining character array of hexadecimal values
private final static char[] hexArray = "0123456789ABCDEF".toCharArray();
//function to convert byte to hex
public static String bytesToHex(byte[] bytes) 
{
char[] hexChars = new char[bytes.length * 2];
for ( int j = 0; j < bytes.length; j++ ) 
{
int v = bytes[j] & 0xFF;
hexChars[j * 2] = hexArray[v >>> 4];
hexChars[j * 2 + 1] = hexArray[v & 0x0F];
}
//returns hexadecimal string
return new String(hexChars);
}
//driver code
public static void main(String args[]) 
{
byte[] bytes = {23, 21, 18, 11};
String str = bytesToHex(bytes);
//loop iterate over the array
for (byte b : bytes) 
{
//converts the byte array to hex value 
String s = String.format("%02X", b);
//prints the corresponding hexadecimal value
System.out.print(s+"\t");
}
}
}

Output: