Convert integer into byte array Java

Question

what s a fast way to convert an Integer into a Byte Array   e g  0xAABBCCDD   gt   AA  BB  CC  DD

User · Answer

You can use BigInteger   From Integers   byte   array   BigInteger valueOf 0xAABBCCDD  toByteArray    System out println Arrays toString array      -- gt   -86  -69  -52  -35     The returned array is of the size that is needed to represent the number  so it could be of size 1  to represent 1 for example   However  the size cannot be more than four bytes if an int is passed   From Strings   BigInteger v   new BigInteger  AABBCCDD   16   byte   array   v toByteArray      However  you will need to watch out  if the first byte is higher 0x7F  as is in this case   where BigInteger would insert a 0x00 byte to the beginning of the array   This is needed to distinguish between positive and negative values

User · Answer

This will help you   import java nio ByteBuffer  import java util Arrays   public class MyClass       public static void main String args              byte    hbhbytes   ByteBuffer allocate 4  putInt 16666666  array             System out println Arrays toString hbhbytes

User · Answer

If you like Guava  you may use its Ints class     For int   byte    use toByteArray     byte   byteArray   Ints toByteArray 0xAABBCCDD     Result is  0xAA  0xBB  0xCC  0xDD      Its reverse is fromByteArray   or fromBytes     int intValue   Ints fromByteArray new byte    byte  0xAA   byte  0xBB   byte  0xCC   byte  0xDD    int intValue   Ints fromBytes  byte  0xAA   byte  0xBB   byte  0xCC   byte  0xDD     Result is 0xAABBCCDD

User · Answer

use this function it works for me  public byte   toByteArray int value        return new byte                  byte  value  gt  gt  24                byte  value  gt  gt  16                byte  value  gt  gt  8                byte value       it translates the int into a byte value

User · Answer

Using BigInteger   private byte   bigIntToByteArray  final int i         BigInteger bigInt   BigInteger valueOf i             return bigInt toByteArray        Using DataOutputStream   private byte   intToByteArray   final int i   throws IOException             ByteArrayOutputStream bos   new ByteArrayOutputStream        DataOutputStream dos   new DataOutputStream bos       dos writeInt i       dos flush        return bos toByteArray        Using ByteBuffer   public byte   intToBytes  final int i         ByteBuffer bb   ByteBuffer allocate 4        bb putInt i        return bb array

User · Answer

Have a look at the ByteBuffer class   ByteBuffer b   ByteBuffer allocate 4     b order ByteOrder BIG ENDIAN      optional  the initial order of a byte buffer is always BIG ENDIAN  b putInt 0xAABBCCDD    byte   result   b array      Setting the byte order ensures that result 0     0xAA  result 1     0xBB  result 2     0xCC and result 3     0xDD   Or alternatively  you could do it manually   byte   toBytes int i      byte   result   new byte 4      result 0     byte   i  gt  gt  24     result 1     byte   i  gt  gt  16     result 2     byte   i  gt  gt  8     result 3     byte   i    gt  gt  0        return result      The ByteBuffer class was designed for such dirty hands tasks though  In fact the private java nio Bits defines these helper methods that are used by ByteBuffer putInt     private static byte int3 int x    return  byte  x  gt  gt  24     private static byte int2 int x    return  byte  x  gt  gt  16     private static byte int1 int x    return  byte  x  gt  gt   8     private static byte int0 int x    return  byte  x  gt  gt   0

User · Answer

It s my solution   public void getBytes int val        byte   bytes   new byte Integer BYTES       for  int i   0 i  lt  bytes length  i               int j   val   Byte MAX VALUE          bytes i     j    0   Byte MAX VALUE   j             Also Stringy method   public void getBytes int val        String hex   Integer toHexString val       byte   val   new byte hex length   2      because byte is 2 hex chars     for  int i   0  i  lt  hex length    i  2          val i    Byte parseByte  0x    hex substring i  i 2   16       return val

User · Answer

very easy with android  int i 10000  byte b1  byte Color alpha i   byte b2  byte Color red i   byte b3  byte Color green i   byte b4  byte Color blue i

User · Answer

Simple solution which properly handles ByteOrder   ByteBuffer allocate 4  order ByteOrder nativeOrder    putInt yourInt  array

User · Answer

Can also shift -  byte   ba   new byte 4   int val   Integer MAX VALUE   for byte i 0 i lt 4 i        ba i     byte  val  gt  gt  i 8         ba 3-i     byte  val  gt  gt  i 8     Big-endian

User · Answer

Here s a method that should do the job just right   public byte   toByteArray int value        final byte   destination   new byte Integer BYTES       for int index   Integer BYTES - 1  index  gt   0  index--                destination i     byte  value          value   value  gt  gt  8             return destination

[java] Convert integer into byte array (Java)

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