Question

In the java project i am working on, some portion of the project was written previously by someone else in C and now i need to write the same in Java.

There is a statement in C code for printing to a file:

fprintf(ff, "%04X ", image[y*width+x]);

Firstly i am not sure about the meaning of %04X. I think it means that if image[i] has length five or more then print only leftmost four chararacters. To do the same in Java i thought about masking the value using and operation

 image[i] & 0xFFFF

Can someone please tell me the correct meaning of %04X and how to do the same in Java? Thanks.

Answer 1

The value is formatted as a hexadecimal integer with four digits and leading zeros. Java uses the same format string syntax. You can find it in the javaDoc of Formatter.

Excerpt:

'x', 'X'     integral    The result is formatted as a hexadecimal integer

A related functions are

// create a String with the formatted value.
String formatted = String.format("%04X ", image[y*width+x]);

// write a formatted value to the console (*)
System.out.printf("%04X ", image[y*width+x]);

_{(*) – write it to the PrintStream System.out which is usually the console but can be redirected to a file or something else}