AbstractAction · AbstractAnnotationValueVisitor6 · AbstractAnnotationValueVisitor7 · AbstractBorder · AbstractButton · AbstractCellEditor · AbstractCollection. Java differs from most other languages in that the number of classes and interfaces in its standard libraries is very large. Many common tasks have already been  Where can I get the list of all java predefined classes and. package. • Java compiler automatically imports all the classes in the package into every classes in the package into every.


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Predefined Packages Java API

In fact, a static method cannot access non-static fields or call non-static methods. Also, methods that are logically associated with a particular class, but that only manipulate the class's static fields should be static. For example, if we wanted a function to print the current value of the numLists field defined above, that predefined classes in java should be defined as a static method of the List class.

A public static field or method can be accessed from outside the class using either the usual notation: Similarly, if the List class includes a public static method PrintNumLists, then the method can be called using either L.

The preferred way to access a static field or a static method is using the class name not using a class object. Predefined classes in java specifiers work on package boundaries between the classes of other packages.

We can find all the related predefined classes in java and interfaces in a single space. Searching and identification will be easier.

Predefined classes « Java Examples Explained

Packages and sub-packages are the easiest way to organize the classes. A package allows importing a single class also instead of importing all.


Since both buttons are associated with the same event listener, we need to make it differentiate between the buttons. On line 42, we use a method called getSource which is inherited from EventObject, a superclass of ActionEvent.


This method returns an object of Object class, which we capture as source. We then check whether source is the same object as logButton line In other words, when a user clicks a button, an event occurs.

With the getSource and equals methods, we can check whether the event is triggered by logButton. If it is, the process of validation lines will start.

Then, on line 60, we check whether the event is triggered by resetButton.


If it is, the statements on lines will be executed. This means both text areas and validation message will be cleared.

Java Classes

Handling Events with Separate Listeners A more common way to perform event handling for more than one GUI elements is using separate event listeners. The following is the modified program: Instead, we have two additional classes which will specifically created for this purpose.

The two classes are predefined classes in java LoginListener lines and ResetListener lines

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