Here is the Huffman code for the input file
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABBBBBBCCCCCCDDDDDDEEEEEEFGHI

Display of Huffman coding tree
           
           +---D: 0.0938, 000 (step 5)
           |   
       +---+---@: 0.1875, 00 (step 7)
       |   |   
       |   +---C: 0.0938, 001 (step 5)
       |   
   +---+---@: 0.4375, 0 (step 8)
   |   |       
   |   |   +---B: 0.0938, 010 (step 6)
   |   |   |   
   |   +---+---@: 0.2500, 01 (step 7)
   |       |   
   |       |           +---G: 0.0156, 011000 (step 2)
   |       |           |   
   |       |       +---+---@: 0.0312, 01100 (step 3)
   |       |       |   |   
   |       |       |   +---F: 0.0156, 011001 (step 2)
   |       |       |   
   |       |   +---+---@: 0.0625, 0110 (step 4)
   |       |   |   |       
   |       |   |   |   +---I: 0.0156, 011010 (step 1)
   |       |   |   |   |   
   |       |   |   +---+---@: 0.0312, 01101 (step 3)
   |       |   |       |   
   |       |   |       +---H: 0.0156, 011011 (step 1)
   |       |   |   
   |       +---+---@: 0.1562, 011 (step 6)
   |           |   
   |           +---E: 0.0938, 0111 (step 4)
   |   
   +---@: 1.0000, 
   |   
   +---A: 0.5625, 1 (step 8)
       
Dump of Table ----->
  Size: 9
Entry 0. Symbol: A, Weight: 0.5625, Representation: 1
Entry 1. Symbol: B, Weight: 0.09375, Representation: 010
Entry 2. Symbol: C, Weight: 0.09375, Representation: 001
Entry 3. Symbol: D, Weight: 0.09375, Representation: 000
Entry 4. Symbol: E, Weight: 0.09375, Representation: 0111
Entry 5. Symbol: F, Weight: 0.015625, Representation: 011001
Entry 6. Symbol: G, Weight: 0.015625, Representation: 011000
Entry 7. Symbol: H, Weight: 0.015625, Representation: 011011
Entry 8. Symbol: I, Weight: 0.015625, Representation: 011010
----> End Dump of Table

Input file (as a String):
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABBBBBBCCCCCCDDDDDDEEEEEEFGHI

Encoded file (as a String):
111111111111111111111111111111111111010010010010010010001001001001001001000000000000000000011101110111011101110111011001011000011011011010

Decoded file (as a String):
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABBBBBBCCCCCCDDDDDDEEEEEEFGHI