[JAVA] Code review points

• Are there any exceptions?
• Does the original exception disappear due to the exception generated in the catch block?
• When wrapping an exception with another exception, do you include the original exception?
• ʻE.printStacktrace` is missing (except when permitted by coding standards, etc.)
• Be able to track the information of the exception that occurred, such as e.addSuppressed, which is output to the log.
• In the comments, specify the reason why you can squeeze it if you can squeeze it.
• Are variables overwritten (except in certain circumstances)?
• The only variables that need to be overwritten are usually counters.
• Are you nesting blocks where early returns are applicable?
• If you are processing with an if block such as if (isXXX) {}, consider whether if (! IsXXX) {return;} can be applied.
• Are there any omissions in closing resources?
• Closeable / AutoCloseable such as InputStream / OutputStream actively uses try-with-resources
• If you do not explicitly close, specify in the comment when to close and why not close
• Is there any excessive checking process?
• Specify in Javadoc whether to allow nulls in public methods or not.
• return null; Code returns a constant that represents Empty as much as possible (such as Optional # empty () and Collections # emptyList ()).
• If return null is in an abnormal state, throw an exception, or use the class that represents the status as the return value.
• Are you using the constants defined in the library etc.
• HTTP status code etc.
• Is IN / OUT processing buffered?
• Use BufferedInputStream instead of raw InputStream, etc.
• Is the specific code that appears frequently properly classified and made into a utility?
• In principle, delegation is based on delegation rather than inheritance.
• is --Are there any inheritance that does not become a? If there are many processes that branch depending on the instance such as * instance of, there is a high possibility that an appropriate inheritance relationship is not maintained.
• Is the resource open in the constructor?
• If you want to open the resource in the constructor, consider static factory method.
• Can constants apply enums?