The parameters of find:

• . -- search in the current directory, and its subdirectories, recursively
• -type f -- match only files
• -name '*.java' -- match only filenames ending with .java
• -exec ... \; -- execute command

The command to execute is slightly complicated, because iconv doesn't rewrite the original file but prints the converted content on stdout. To update the original file we need 2 steps:

1. Convert and save to a temp file
2. Move the temp file to the original

To do these steps, we use a sh subshell with -exec, passing a one-liner to run with the -c flag, and passing the name of the file as a positional argument with -- {}.

Unfortunately the redirection will use UNIX style line endings. If the original files have DOS style line endings, add this command in the subshell:

vim +'set ff=dos' +wq converted