Add comments for the Java analyzer

analyzer-comments/java/general/avoid_print_statements.md

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+# avoid print statements
+
+Try removing statements such as `System.out.println()` from your code.
+Exercise tests require the solution to _return_ values from methods instead of printing them.
+
+Usually, statements like these are added to help debug the code.
+However, a better approach is to debug the code while running one or more unit tests.
+This has the added advantage that one can focus on debugging a specific test case.
+
+Here are some links that explain how to debug Java code while running unit tests in various IDEs:
+
+- [Running and debugging Java tests in Visual Studio Code](https://code.visualstudio.com/docs/java/java-testing#_rundebug-test-cases)
+- [Debugging tests in IntelliJ IDEA](https://www.jetbrains.com/help/idea/performing-tests.html#RedebugFailedTests)

analyzer-comments/java/general/do_not_use_main_method.md

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+# do not use main method
+
+Try removing the `main` method from your code.
+Exercise tests don't require solutions to have a `main` method and having one makes the code slightly harder to read.
+
+Usually, a `main` method is added to help debug the code.
+However, a better approach is to debug the code while running one or more unit tests.
+This has the added advantage that one can focus on debugging a specific test case.
+
+Here are some links that explain how to debug Java code while running unit tests in various IDEs:
+
+- [Running and debugging Java tests in Visual Studio Code](https://code.visualstudio.com/docs/java/java-testing#_rundebug-test-cases)
+- [Debugging tests in IntelliJ IDEA](https://www.jetbrains.com/help/idea/performing-tests.html#RedebugFailedTests)