Encoding and Decoding in base64

Base64.java

package base64;

public class Base64 {
	
	private static String CODES = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
			+ "abcdefghijklmnopqrstuvwxyz"
			+ "0123456789+/=";
	
	public static String encode(byte[] input){
		
		StringBuilder out = new StringBuilder(input.length * 4 / 3);
				
		int b;
		for(int i = 0; i < input.length; i+=3){
			
			b = ((input[i] & 0xFC) >> 2);
			out.append(CODES.charAt(b));
			
			b = (input[i] & 0x03) << 4;
			
            if (i + 1 < input.length)      {
                b |= (input[i + 1] & 0xF0) >> 4;
                out.append(CODES.charAt(b));
                b = (input[i + 1] & 0x0F) << 2;
                
                if (i + 2 < input.length)  {
                    b |= (input[i + 2] & 0xC0) >> 6;
                    out.append(CODES.charAt(b));
                    b = input[i + 2] & 0x3F;
                    out.append(CODES.charAt(b));
                } else  {
                    out.append(CODES.charAt(b));
                    out.append('=');
                }
                
            } else {
                out.append(CODES.charAt(b));
                out.append("==");
            }
				
		}
				
		return out.toString();
		
	}
	
	
	public static byte[] decode(String in){
		
		if(in.length() % 4 != 0){
			throw new IllegalArgumentException("Invalid input");
		}
		
		int lengthOfDecoded = ((in.length() * 3)/4) - (in.indexOf("=")>0?(in.length()-in.indexOf("=")) : 0);
		byte[] decoded = new byte[lengthOfDecoded];
		
		char[] inChars = in.toCharArray();
		
		int[] b = new int[4];
		int j = 0;
		
		for(int i = 0; i < inChars.length; i+=4){
			
			b[0] = CODES.indexOf(inChars[i]);
			b[1] = CODES.indexOf(inChars[i+1]);
			b[2] = CODES.indexOf(inChars[i+2]);
			b[3] = CODES.indexOf(inChars[i+3]);
			
			decoded[j++] =(byte) ((b[0] << 2) | (b[1] >> 4));
			if(b[2] < 64){
				decoded[j++] = (byte) ((b[1] << 4) | (b[2] >> 2));
                if (b[3] < 64)  {
                    decoded[j++] = (byte) ((b[2] << 6) | b[3]);
                }
			}
		}
		
		return decoded;
		
	}
	
}