Return the first bytes from a byte array - Java java.lang

Description

Return the first bytes from a byte array

Demo Code

//package com.java2s;

public class Main {
    public static void main(String[] argv) throws Exception {
        byte[] bytes = new byte[] { 34, 35, 36, 37, 37, 37, 67, 68, 69 };
        int len = 2;
        System.out.println(java.util.Arrays.toString(head(bytes, len)));
    }/* w ww .ja  v  a 2  s  .com*/

    /**
     * Return the first bytes from a byte array
     */
    public static byte[] head(byte[] bytes, int len) {
        if (len > bytes.length) {
            throw new IllegalArgumentException(
                    "Can't ask for more data than is present");
        }
        byte[] buff = new byte[len];
        System.arraycopy(bytes, 0, buff, 0, buff.length);
        return buff;
    }

    /**
     * Print a byte array as a String
     */
    public static String toString(byte[] bytes) {

        StringBuilder sb = new StringBuilder(4 * bytes.length);
        sb.append("[");

        for (int i = 0; i < bytes.length; i++) {
            sb.append(unsignedByteToInt(bytes[i]));
            if (i + 1 < bytes.length) {
                sb.append(",");
            }
        }

        sb.append("]");
        return sb.toString();
    }

    /**
     * Convert an unsigned byte to an int
     */
    public static int unsignedByteToInt(byte b) {
        return (int) b & 0xFF;
    }
}

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