I think it's the simplest algorithm so far (for those who don't want to use built-in functions):
public static String convertNumber(int a) {
StringBuilder sb=new StringBuilder();
sb.append(a & 1);
while ((a>>=1) != 0) {
sb.append(a & 1);
}
sb.append("b0");
return sb.reverse().toString();
}
Example:
convertNumber(1) --> "0b1"
convertNumber(5) --> "0b101"
convertNumber(117) --> "0b1110101"
How it works: while-loop moves a-number to the right (replacing the last bit with second-to-last, etc), gets the last bit's value and puts it in StringBuilder, repeats until there are no bits left (that's when a=0).