byte取高4位，低4位，byte转int

byte abyte =-1;
    System.out.println(abyte);
    System.out.println(Integer.toBinaryString(abyte));
    //取高四位
    byte high = (byte) ((abyte>>4) & 0x0f);
    System.out.println("取高四位"+Integer.toBinaryString(high));
    //取低四位
    byte low =  (byte) (abyte & 0x0f);
    System.out.println("取低四位"+Integer.toBinaryString(low));
    //byte转int保持数值不变
    int b= (int)abyte;
    System.out.println(b);
    //byte转int保持最低字节中各个位不变
    int c= (int)(abyte & 0xff);
    System.out.println(c);