Why is java.util.Observable not an abstract class? -

-

I have just seen that java.util.Observable is a solid square. Since inspection is to be expanded, so it seems strange to me. Is there any reason to apply it like this?

I found that which is called

This is a visible square, so the section receiving it should be determined in advance, as Java is only a single succession Allows

But it does not really convince me, in fact, if there was insightful essence, then the user would be compelled to determine the class from it.

As the first approach, it may think that the user is allowed to use the structure instead It is a heritage, which is very convenient If your class has already been from another class , and you can not even inherit from the observation class.

But if we look at the source code of the observation, then we see that there is an internal flag 

  the private boolean changed = false;   
 Each time the notification oscillator is implemented:  
  notify the public zodiac (object arg) {object [] arrLocal; Synchronize (this) {if (changed!) Return; ArrLocal = obs.toArray (); ClearChanged (); } For (int i = arrLocal.length-1; i> = 0; i--) ((inspector) arrLocal [i]). Update (this, arg); }   
 But , we can not change this flag  from the square created by this supervisor, because it is private, and given methods to change it Are preserved.  
 This means that the user is forced to sub-class the observation class, and I would say that the lack of "abstract" keyword is just a "mistake".  
 I would say that this class is a complete screw.

Comments

Post a Comment

Popular posts from this blog

mysql - BLOB/TEXT column 'value' used in key specification without a key length -

-
I have developed an extension which works up to 1.6 on Magren (I'm trying Enterprise Edition, And I think the community is the same problem, because it is the same code). In my install script, I see the $ installer-> gt; CreateEntityTables ($ this- & gt; getTable ('alphanum / info')); The installation is done until it is not in the _text unit table. It crashed there! It turns out that when I log in to SQL and run it via PHPmyadmin, then this error is: Blob / Text column 'value' is used without the key 'key' . I saw the code there, and this is what is trying to create an index on the value column: -> addIndex ($ this- & gt; getIdxName ($ eavTableName, array ( 'attribute_id array (' attribute_id ',' value ')) - & gt; addIndex ($ this- & gt; getIdxName ($ eavTableName, array (' entity_type_id ' , 'Value')), array ('entity_type_id', 'value')) If there is no if statement is n...
Read more

c# - Using Vici cool Storage with monodroid -

-
Oh, for the moment I am not sure how it is officially supported, but for the success of the people Using Monodroid Vic Cool Storage I am able to leave and compile assemblies in my project, but while trying to use some classes, the errors of time have to be gathered. Especially when trying to connect like the example for Mono Touch string dbName = path. Cobain (environment. Gatefolder path (environment specialfolder personal), "mydb.db3"); // The following line will be called coolestation, where is the database, // to make it if it does not exist, and call a delegate that creates the necessary tables (only when the database file was newly created //) CSConfig.SetDB (DbName, true, () => {CSDatabase.ExecuteNonQuery ("Subscriber Integer Primary Key Attribute, Name Text (50) No, Number, Date First Text (30)");); There is no difference when I try to use the methods of CSConfig and when I cscfif If I try to pass 3 aggregates to STDB (3) then I get the invalid ...
Read more

python - referencing a variable in another function? -

-
I am an experienced TCL developer and write my own processes to help myself. I call it a proc i callVar, print out the value of the variable in a certain format, so I know that it is variable and what is the value "set foo 1; putVar foo" result 'foo = "1" I want to do the same thing in Python, but I can not find the answer :( In TCL I use the up command because when I pass the name of the variable, then I can see the value at the top. . I understand that an advanced light in the dragon There is no mechanism of r, but with its introspection capability, I would think that this is something trivial, but I am not getting the answer anywhere. It seems that this should work: and expanded: def foo (): y = "Hello World" printwor ("y") foo () y = "Hello World " You can, but you should not do so if your code is correct If is needed , then there is something wrong with your design, and you should probably use the dictionar...
Read more