Changes between Version 4 and Version 5 of CODE_TASKS_REQUIREMENTS

Timestamp:

09/16/08 18:00:19 (17 years ago)

Author:

Tanya

Comment:

--

CODE_TASKS_REQUIREMENTS

@@ -158 +158 @@
 
 Always rethrow the exception if You dont have information how to handle it.
-Since PropertyVetoException is checked exception, it may be good to wrap it in a RuntimeException.
+Since !PropertyVetoException is checked exception, it may be good to wrap it in a !RuntimeException.
 Consult other people and think of exception handling policy.
 
@@ -173 +173 @@
         }
 }}}
+
+= Global variables =
+
+Do NOT use global variables as a way to pass arguments between non-public methods.
+This is an unclear method, potentially very dangerous - a lot of mistakes can be done using it.
+
+= Use final =
+Usage of final modifier for classes, methods,and especially class members and method variables is a very good practise and prevents from a number of mistakes.
+
+== classes ==
+When writing a class, one of the things we have to think of is - 'is our class designed in a way that it can be inherited?'
+In 90% of the cases the answer of this question is 'NO'. However if we don't make it final, some people may decide to inherit it and this will cause a lot of problems.
+There are some very famous examples of such mistakes being made:
+java.sql.Date inherits java.util.Date and it causes a lot of problems - You can read about them here:
+[http://www.thunderguy.com/semicolon/2003/08/14/java-sql-date-is-not-a-real-date/]
+The problem all starts from the fact that in the documentation of java.util.Date it is written that the class should not be inherited,but it was not declared final.
+Always put final modifier for your classes if they are not designed to be inherited.
+
+== class methods ==
+Sometimes we design our classes for inheritance but there are some public methods that are critical and we do not want the inheritant to override them - again put final modifier.
+
+== class variables ==
+When we have a class member that is initialized in the constructor and should never be changed through all the instance life - ALWAYS put final modifier.
+This will prevent someone change the refference of that class member, that would have lead to wrong behaviour.
+
+In !FrameView class, we have !PageView parent, that was has to be final but it is not.
+{{{
+private PageView parent;
+}}}
+Replaced with:
+{{{
+private final PageView parent;
+}}}
+== method variables ==
+The same as class members.
+{{{
+        public void saveAs() {
+                File file = selectSaveFile();
+                if(file != null){
+                        this.book.saveTo(file);
+                }
+        }
+}}}
+file shall be declared private.