As an input I have binary string String a = "100110". As output I need to have binary byte array byte[] b = {1,0,0,1,1,0}.
For now I'm using
for (int i=0; i<a.length; i++) {
b[i]= Byte.parseByte(a.substring(i, i+1));
}
But this approach is too slow. Can any one give a better suggestion? Thank you
You can do it without making objects for substrings, like this:
for (int i=0; i<a.length; i++) {
b[i]= a.charAt(i)=='1' ? (byte)1 : (byte)0;
}
The reason your approach is slower is that each call to substring produces a new String object, which becomes eligible for garbage collection as soon as parseByte is done with it.
Assuming the input is valid...
byte[] b = new byte[a.length()];
for (int i = 0; i < b.length; i++) {
b[i] = (byte) (a.charAt(i) - '0');
}
Makes an int[] instead of byte[] but I hope for points for elegance:
int[] a = "100110"
// Turn it into a stream.
.chars()
// Make '0'/'1' into 0/1
.map(c -> c - '0')
// Roll it into an array.
.toArray();
