Help converting byte array to String and long

[jeffbroodwar]

Hi everyone,

I have a program that converts variables long,string,dou ble to byte array here's the code :

for long :

       //CompanyId
       temp = longToByteArray(CompanyId);
       for (i=0,i2=7; i<5; i++,i2--)
           buffer[position + i] = temp[i2];

       private byte[] longToByteArray(long l) 
       {
          byte[] bArray = new byte[8];
          ByteBuffer bBuffer = ByteBuffer.wrap(bArray);
          LongBuffer lBuffer = bBuffer.asLongBuffer();
          lBuffer.put(0, l);
          return bArray;
        }

for String :

         //CustomerCode
        for (i=0; i <20; i++)
        {
           if (i < customerCode.length())
               buffer[i + position] = (byte) customerCode.charAt(i);
           else
               buffer[i + position] = 0;
        }

for double :

       // LastClaimPoints
       temp = longToByteArray( Double.doubleToRawLongBits(LastClaimPoints));
       for (i=0; i<8; i++)
           buffer[position+i] = temp[i];


       private byte[] longToByteArray(long l) 
       {
          byte[] bArray = new byte[8];
          ByteBuffer bBuffer = ByteBuffer.wrap(bArray);
          LongBuffer lBuffer = bBuffer.asLongBuffer();
          lBuffer.put(0, l);
          return bArray;
        }

Now the problem is i don't know how to convert it back. Byte array back to its
different datatypes (long, String, double).

any help will be appreciated,

Regards,
Jeff

[JosAH]

Now the problem is i don't know how to convert it back. Byte array back to its
different datatypes (long, String, double).

any help will be appreciated,

Regards,
Jeff

You can wrap that byte array in a ByteBuffer again and use one of the getX()
methods that return your doubles, longs etc. again. check the API docs for that
class.

kind regards,

Jos

[jeffbroodwar]

Hi Jos,

Can you show me how it's done? i have a sample code here that will retrieve a long datatype value from a specific index of the byte array... but the problem is, it returns a very long number value ex : 456223344136444 64646 don't know how should i fix this... anyway here's the code...

        ByteBuffer a = ByteBuffer.wrap(buffer);
        long testLong = a.getLong(buffer[1]);
        System.out.println("Value : " + testLong);

i need to retrieve string, long and double.... thanks !

Regards,
Jeff

[JosAH]

Hi Jos,

Can you show me how it's done? i have a sample code here that will retrieve a long datatype value from a specific index of the byte array... but the problem is, it returns a very long number value ex : 456223344136444 64646 don't know how should i fix this... anyway here's the code...

        ByteBuffer a = ByteBuffer.wrap(buffer);
        long testLong = a.getLong(buffer[1]);
        System.out.println("Value : " + testLong);

i need to retrieve string, long and double.... thanks !

Regards,
Jeff

I think the parameter to the getLong( ... ) method is wrong: you're using 'bufffer'
to be wrapped in the ByteBuffer and you're also using buffer[1] as the index value.

Shouldn't it read something like 'getLong(1)'? In this case the buffer byte array
is read, starting at position 1, and a long value is constructed.

kind regards,

Jos

[jeffbroodwar]

Hi Jos,

Thanks for helping... still i can't get what i want to get.... here's the datatype of the variables :

    byte   FormatId;         // byte (1) 
    long   CompanyId;        // long (5)
    String CompanyName;      // string (30)
    byte   customerLevelId;  // byte (1)  
    String customerCode;     // string (20)
    String CustomerName;     // string (50)
    String Birthday;         // string (6)
    String ExpiryDate;       // string (6)
    long   totalAmountSold;  // long (8)
    double balancePoints;    // double (8)
    String lastSaleDate;     // string (6)
    String LastClaimDate;    // string (6)
    double LastClaimPoints;  // double (8)
    long   UpdateCount;      // long (8)

and here's the value for each variables :

        // c.variable ? because variable is located in another class..... FYI only... ^^
        c.FormatId = 1;
        c.CompanyId = 127;
        c.CompanyName = "Cripple";
        c.customerLevelId = 1;
        c.customerCode = "ABCDE12345ABCDE12345X";
        c.CustomerName = "Victory Kups";
        c.Birthday = "060685";
        c.ExpiryDate = "060685";
        c.totalAmountSold = 257;
        c.balancePoints = 1.999;
        c.lastSaleDate = "060107";
        c.LastClaimDate = "060685";
        c.LastClaimPoints = 100.00;
        c.UpdateCount = 3;

I'm still trying other solutions for this..... never quit right? ehehe thanks man.


Best regards,
Jeff

[Aeren]

It's been 4 years since last post, but I still found this thread ^^ So if anyone is wondering why it still wasn't working, it's just that arrays start at position 0, so you should use getLong(0). That gives the following code :

ByteBuffer a = ByteBuffer.wrap(buffer);
long testLong = a.getLong(0);
System.out.println("Value : " + testLong);