[JAVA] Check compliance with object-oriented exercise

Overview

Object-oriented exercise is introduced in the book Thought Works Anthology. Nine rules that can improve software design are introduced. The good and bad of this rule is introduced in various places, so please refer to that.

Based on these, there is one big problem in actually practicing object-oriented exercise. There is no way to check how well they are compliant. Of course, you can check it visually, but it is very difficult to check all the programs, and the number of methods and the number of lines cannot be counted. On the contrary, since the rules themselves are firmly established, it should be possible to confirm them programmatically. When I searched for it, I couldn't find such a confirmation tool. So, it is a promotion that I tried to make a confirmation tool. In creating it, I practiced object-oriented exercise.

9rules

It is a tool published at https://github.com/tamada/9rules. It is a tool that targets Java source code and points out points that violate the nine rules of object-oriented exercise.

Installation & usage

$ git clone https://github.com/tamada/9rules.git
$ cd 9rules
$ mvn package
$ java -jar target/9rules-1.0-SNAPSHOT.jar -h
java -jar 9rules.jar [OPTIONS] <ARGUMENTS...>

OPTIONS:
    --strict:  Strictly level check (Default).
    --general: General level check.
    --rough:   Rough level check.
    --help:    Print this message and exit.

ARGUMENTS:
    Directories include Java source files, and Java source files.
$ java -jar target/9rules-1.0-SNAPSHOT.jar src/main/java

Dependent libraries

Runtime
- Eclipse JDT
- CheckerFramework
Unit Test
- JUnit 4.12
- Hamcrest-all

Feature

What you can do

Output the part that does not meet the 9 rules (file name, number of lines, violating rule).
You can relax the rules and check (3 patterns of Strict, General, Rough. Default is Strict)

Things impossible

Rule 5 Do not omit the name is not implemented.
I think it can be done by using WordNet, but it is not supported.
Rule 6 Make all entities smaller 1 package 10 classes are not implemented.
Because the survey method is different from other rules. The survey itself is not so difficult, but I am thinking about how to combine it with the survey method with other rules.

Try object-oriented exercise

What is necessary for compliance.

Java 8 or later.
Stream API required.
Just using the for statement makes compliance very difficult.
Design pattern.
Required such as Strategy.
Above all, the Visitor pattern is essential.
Typically required when you want to retrieve the contents of an object in a field, such as toString.

Very difficult to comply with.

Difficult to catch exceptions.
``` Rule 6 Make all entities smaller` `` method is very difficult to comply with within 3 lines.
try-catch cannot omit the brace (`` {} `). Therefore, try, catch, and closing parenthesis consume 3 lines, and the contents of the catch clause cannot be written in another line between try-catch.
Conflicts may occur when trying to resolve Sonar and SpotBugs warnings as well.
A conflict occurs with try-catch because a warning is issued to make only one content per line.
I still don't know how to solve this.