Question

I have to write a biginteger into a text file using the following statement.

out.writeObject(n1);

where my n1 is a biginteger of length 512 bits.

On reading the same object from the text file gives me a different value to n1. Could anyone help me with the problem.
The statement used to read the value is :

in.readObject();

Thanks in advance.

Answer 1

You forgot to post SSCCE, so here is one for you:

BigInteger big = new BigInteger("515377520732011331036461129765621272702107522001");
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ObjectOutputStream outputStream = new ObjectOutputStream(baos);
outputStream.writeObject(big);
byte[] rawBytes = baos.toByteArray();

ObjectInputStream inputStream = new ObjectInputStream(new ByteArrayInputStream(rawBytes));
BigInteger bigReadBack = (BigInteger) inputStream.readObject();

assertThat(big).isEqualTo(bigReadBack);

Works like a charm, serializing and deserializing 3^100. Can you try the code above?

UPDATE: example with file (sorry for non-descriptive variable names):

BigInteger big = new BigInteger("515377520732011331036461129765621272702107522001");
OutputStream fos = new FileOutputStream("big.ser");
ObjectOutputStream outputStream = new ObjectOutputStream(fos);
outputStream.writeObject(big);
fos.close();

ObjectInputStream inputStream = new ObjectInputStream(new FileInputStream("big.ser"));
BigInteger bigReadBack = (BigInteger) inputStream.readObject();

assertThat(big).isEqualTo(bigReadBack);

BTW storing Java-serialized binary data in a file with .txt extension is generally a bad idea… And don’t forget about caching! (BufferedInputStream/BufferedOutputstream).