Convert a Byte Array to a Numeric Representation in Java

How to Convert a Byte Array to a Numeric Representation in Java

In Java, it is sometimes necessary to convert a byte array to an integer or other numeric representation. There are many ways to do this, and the best method depends on the data type and structure of the byte array. In this tutorial, we'll discuss some of the different methods available for converting a byte array to a numeric representation in Java.

Using ByteBuffer and Integer/Long/Double Classes

The most common approach is to use the ByteBuffer class in combination with the Integer, Long, and Double classes. For example, to convert a byte array to an int, we can use the following code:

byte[] bytes = ...;
ByteBuffer buf = ByteBuffer.wrap(bytes);
int value = buf.getInt();

Similarly, for a long, we can use:

byte[] bytes = ...;
ByteBuffer buf = ByteBuffer.wrap(bytes);
long value = buf.getLong();

And for a double, we can use:

byte[] bytes = ...;
ByteBuffer buf = ByteBuffer.wrap(bytes);
double value = buf.getDouble();

Using Parse Methods

In addition to using the ByteBuffer and Integer/Long/Double classes, we can also convert a byte array to a numeric representation using the parse methods available in the Integer, Long, Double and BigInteger classes. For example, to convert a byte array to an int, we can use the parseInt() method:

byte[] bytes = ...;
String s = new String(bytes);
int value = Integer.parseInt(s);

Similarly, for a long, we can use the parseLong() method:

byte[] bytes = ...;
String s = new String(bytes);
long value = Long.parseLong(s);

And for a double, we can use the parseDouble() method:

byte[] bytes = ...;
String s = new String(bytes);
double value = Double.parseDouble(s);

Conclusion

In this tutorial, we discussed some of the different methods available for converting a byte array to a numeric representation in Java. We used the ByteBuffer and Integer/Long/Double classes, as well as the parse methods from the Integer, Long, Double and BigInteger classes. Depending on the data type and structure of the byte array, any of these methods can be used to achieve the desired result.