Java print four byte hexadecimal number

Question

I have a small problem. I have numbers like 5421, -1 and 1. I need to print them in four bytes, like:

5421 -> 0x0000152D
-1   -> 0xFFFFFFFF
1    -> 0x00000001

Also, I have floating point numbers like 1.2, 58.654:

8.25f -> 0x41040000
8.26  -> 0x410428f6
0.7   -> 0x3f333333

I need convert both types of numbers into their hexadecimal version, but they must be exactly four bytes long (four pairs of hexadecimal digits).

Does anybody know how is this possible in Java? Please help.

Solution 1

Here are two functions, one for integer, one for float.

public static String hex(int n) {
    // call toUpperCase() if that's required
    return String.format("0x%8s", Integer.toHexString(n)).replace(' ', '0');
}

public static String hex(float f) {
    // change the float to raw integer bits(according to the OP's requirement)
    return hex(Float.floatToRawIntBits(f));
}

Solution 2

For Integers, there's an even easier way. Use capital 'X' if you want the alpha part of the hex number to be upper case, otherwise use 'x' for lowercase. The '0' in the formatter means keep leading zeroes.

public static String hex(int n) 
{
    return String.format("0x%04X", n);
}

Solution 3

Here it is for floats:

    System.out.printf("0x%08X", Float.floatToRawIntBits(8.26f));

Solution 4

Use

String hex = Integer.toHexString(5421).toUpperCase();  // 152D

To get with leading zeroes

String hex = Integer.toHexString(0x10000 | 5421).substring(1).toUpperCase();

View more solutions

Comments

[Kevin Bowersox]

System.out.println(Integer.toHexString(5421)); --> 152d

[Sri Harsha Chilakapati]

The java doc says that it gives without leading zeroes.

[Hui Zheng]

@SriHarshaChilakapati but the OP requires the leading zeros.

[Kevin Bowersox]

Nice answer, gives the leading 0's as requested.

[Hui Zheng]

@SriHarshaChilakapati Your updated answer still has bug, try replacing 5421 with 99999999.

[Hui Zheng]

@user35443 floats are different, can you add samples for floats in your question?

[Victor Zamanian]

The hex(int) method could also have a format of "%#08x", to print the "0x" and leading zeros for you.