Peer-to-peer network implementation is added.
Note, I made a mistake in April 2022 when I tried to update the old .rar file to .zip files. I did not upload correct Chapter 9 codes for edition 2. This problem was corrected on May 3, 2022. Sorry for the confusion and thanks.
On 11-14-2024, found a single quotation mark of MS Word type inside the comment area in the class Wallet.java. Though it is in the comment, it causes compilation error for Java 22. Fixed it in both Chapter 9 and Chapter 10.