generate positive random number and right shift by 8 bits and store in a byte

I am struck at writing a java equivalent code for a C code to generate random number. The C code is as follows : static void lng_cosem_CreateRandom(u8 *u8p_Array_p, u8 u8_Len_p) { u8 u8_Indx; u32 u32_Temp;

                #if ( _COMPILER_MICROSOFT_VC == LNG_COMPILER_USED )
                srand(GetTickCount());
                #endif /* LNG_COMPILER_USED */
               while( u8_Len_p )
              {
                  u32_Temp = SYS_GetRandom32();
                  for( u8_Indx = 0; u8_Indx < 4; u8_Indx++ )
                  {
                       *u8p_Array_p++ = (u8)u32_Temp;
                        u32_Temp >>= 8;
                        u8_Len_p--;
                        if( !u8_Len_p )
                        {
                                break;
                        }
                  }
            }
      }

I wrote a Java equivalent code to the above as follows :

         public  static void CreateRandom(byte[] COSEM_CTOS, byte   
     COSEM_CHALLENGE_LEN)  
      {                 
             long temp;
             int index;
             pos = 0;
             while(COSEM_CHALLENGE_LEN!=0)
            {
                   Random rand = new Random();
                   temp = Math.abs(rand.nextInt());
                   System.out.println(temp + "absolute val");
                   for(index=0;index<4;index++)
                   {
                        COSEM_CTOS[pos++] = (byte) temp;
                        temp >>= 8;
                        System.out.println(temp + "right shift value");
                        COSEM_CHALLENGE_LEN--;
                        if(COSEM_CHALLENGE_LEN == 0 )
                        {
                             break;
                        }
                    }
             }
         }

But i get negative numbers after the right shift operation.I want only positive numbers. How can i do it ?