Question

I’m trying to serialize/deserialize a bitmap. The answers at android how to save a bitmap – buggy code are very helpful. However, when I go to read my array:

private void readObject(ObjectInputStream in) throws IOException,
    ClassNotFoundException {
  int rowBytes = in.readInt();
  int height = in.readInt();
  int width = in.readInt();
  int bmSize = rowBytes * height;    // Ends up being 398208

  ByteBuffer byteBuffer = ByteBuffer.allocate(bmSize);
  int bytesRead = in.read(byteBuffer.array(), 0, bmSize);
  // Use array to create bitmap here
}

it is reading 1008 bytes, not the 398208 bytes that I wrote. I’ve replaced the call with a loop, which works fine:

for (int i = 0; i < bmSize; i++) {
  byteBuffer.array()[i] = in.readByte();
}

What could be going wrong? No exception is thrown. The documentation for ObjectInputStream.read(byte[], int, int) indicates the only reason it should return early is if it hits the end of the stream, which clearly it isn’t because my work-around doesn’t throw any exceptions.

Answer 1

The documentation is wrong. ObjectInputStream just calls inputStream to read the bytes. Use readFully if you want it to block until the data is read.