How can i write a program converting from hexadecimal to binary in java?

Answer 1

First of: I can do that in a simple for loop:

public static long bin2dec(char[] input) {

long dec = 0; // return value

for (int i = 0; i < input.length; i++) // No curly braces because its just one line; IT WILL WORK, but you can add curly braces

if (input[i] - 48 > 1) return null; // same here

else dec = (dec << 1) + input[i] - 48; // and here

return dec;

}

The recursion variant of the bin2dec can crash the stack:

public static long bin2dec(char[] input) {

char[] nextInput = new char[input.length - 1]; // char-array for the next recursion

for (int i = 0; i < newInput.length; i++) nextInput[i] = input[i];

return (input[input.length - 1] - 48) + bin2dec(nexInput) << 1;

}

Answer 2

I presume you really mean how do you convert a value to a binary string for printing purposes. E.g., the decimal value 42 should print "0b101010" (the 0b prefix is optional, but helps to distinguish binary values from decimal values).

Integers are reasonably simple to convert:

int i = 42;

System.out.println(Integer.toString(i) + " = 0b" + Integer.toBinaryString(i));

Doubles are a bit more complex:

double d = Math.pow(2, 900);

System.out.println(Double.toString(d) + " = 0b" + Long.toBinaryString(Double.doubleToRawLongBits(d)));

For more complex types (such as class representations), treat the type as if it were an array of type char, then print the binary value of each char (padding with leading zeroes where necessary).

Be aware that although Java uses big-endian binary representations, this may or may not match the representations used by the underlying architecture. This is important when converting values generated outside of Java (such as values stored in binary files generated from other programs). Before converting these values you first need to determine the underlying type of the value and then convert to a corresponding Java type. This ensures the bytes are in the correct order regardless of the physical representation. If you really want the physical representation then just treat the value as an array of type char.

Answer 3

Take a look at this page.Complete source code to get binary value from hexadecimal:

http://java2everyone.blogspot.com/2009/04/java-hexadecimal-to-binary.html