In Java, can I define an integer constant in binary format?

Question

Similar to how you can define an integer constant in hexadecimal or octal, can I do it in binary?

I admit this is a really easy (and stupid) question. My google searches are coming up empty.

Answer 1

In Java 7:

int i = 0b10101010; 

There are no binary literals in older versions of Java (see other answers for alternatives).

Answer 2

So, with the release of Java SE 7, binary notation comes standard out of the box. The syntax is quite straight forward and obvious if you have a decent understanding of binary:

byte fourTimesThree = 0b1100; byte data = 0b0000110011; short number = 0b111111111111111;  int overflow = 0b10101010101010101010101010101011; long bow = 0b101010101010101010101010101010111L; 

And specifically on the point of declaring class level variables as binaries, there's absolutely no problem initializing a static variable using binary notation either:

public static final int thingy = 0b0101; 

Just be careful not to overflow the numbers with too much data, or else you'll get a compiler error:

byte data = 0b1100110011; // Type mismatch: cannot convert from int to byte 

Now, if you really want to get fancy, you can combine that other neat new feature in Java 7 known as numeric literals with underscores. Take a look at these fancy examples of binary notation with literal underscores:

int overflow = 0b1010_1010_1010_1010_1010_1010_1010_1011; long bow = 0b1__01010101__01010101__01010101__01010111L; 

Now isn't that nice and clean, not to mention highly readable?

I pulled these code snippets from a little article I wrote about the topic over at TheServerSide. Feel free to check it out for more details:

Java 7 and Binary Notation: Mastering the OCP Java Programmer (OCPJP) Exam