There are two complementary ways of depending on something from outside a given plug-in; Require-Bundle and Import-Package.
Using the Require-Bundle manifest header, plug-ins specify an explicit dependency on a specific bundle and version. As such, the required bundles are placed logically on the dependent plug-in's classpath.
Import-Package is used to declare a dependency on a package without knowing which exact bundle will provide it. Any bundle in the environment must export the package with Export-Package for the Import-Package to be resolved.
To determine if a literal is valid with respect to a simple type, you can use either XSDSimpleTypeDefinition.isValidLiteral or XSDSimpleTypeDefinition.assess.
A layout is only performed automatically on a Composite's children when the Composite is resized, including when it is initially shown. To make a Composite lay out its children under any other circumstances, such as when children are created or disposed, its layout() method must be called.
To fire a key occasion in check code to make the program act as if a user pressed a key.You need to comply with ways. NotifyListeners(…) or
publish(Event)
Two ways to implement it in code: generating OS level key event use Display.post(Event) or use Widge.notifyListeners(...) to just notify a widget's listeners.
The OSGi parent class loader. (Java boot class loader by default); The exported libraries of all imported plug-ins; The declared libraries of the plug-in and all its fragments.
Application code must explicitly invoke the Image.dispose() method to release the operating system resources managed by each instance when those instances are no longer required. This is because that the Java finalization is too weak to reliably support management of operating system resources.
The Display class respresents the GUI process(thread), the Shell class represents windows.
A layout is only performed automatically on a Composite's children when the Composite is resized, including when it is initially shown. To make a Composite lay out its children under any other circumstances, such as when children are created or disposed, its layout() method must be called.
To determine if a literal is valid with respect to a simple type, you can use either XSDSimpleTypeDefinition.isValidLiteral or XSDSimpleTypeDefinition.assess.
plug-in prerequisite elements can be made optional by adding the optional="true" attribute in Manifest file(see below for an example). Marking an import as optional simply states that if the specified plug-in is not found at runtime, the dependent plug-in should be left enabled. This is used when a plug-in can be used in many scenarios or it is reasonable to operate with reduced function. It allows the creation of minimal installs that cover functional subsets. Require-Bundle: org.eclipse.swt; optional="true"
The Eclipse Modeling Framework is a Java/XML framework for generating tools and other applications based on simple class models. EMF helps you rapidly turn models into efficient, correct, and easily customizable Java code. It is intended to provide the benefits of formal modeling, but with a very low cost of entry. In addition to code generation, it provides the ability to save objects as XML documents for interchange with other tools and applications.
Eclipse Runtime, SWt, JFace, Workbench
There are two complementary ways of depending on something from outside a given plug-in; Require-Bundle and Import-Package.
The simplest implementation that can be given is that of a List wherein one can place ordered words and perform a Binary search. The other implementation with a better search performance is HashMap where the key is used as the first character of the word and the value as a LinkedList.
Up another level, there are HashMaps like:
hashmap {
a (key) -> hashmap (key-aa , value (hashmap(key-aaa,value)
b (key) -> hashmap (key-ba , value (hashmap(key-baa,value)
z (key) -> hashmap (key-za , value (hashmap(key-zaa,value)
}
Up to n levels where n is the average size of the word in the dictionary.
System.out and System.err represent the monitor by default and thus can be used to send data or results to the monitor. System.out is used to display normal messages and results. System.eerr is used to display error messages. System.in represents InputStream object which by default represents standard input device, i.e., keyboard.
FailFast iterators and FailSafe iterators are used in Java Collections.
FailFast iterators do not allow changes or modifications to the Java Collections, which means they fail when the latest element is added to the collection or an existing element gets removed from the collection. The FailFast iterators tend to fail and throw an exception called ConcurrentModificationException.
Ex: ArrayList, HashMap
Whereas, on the other hand, FailSafe iterators allow changes or modifications to be done on the Java Collections. It is possible, as the FailSafe iterators usually operate on the cloned copy of the collection. Hence, they do not throw any specific exception.
Ex: CopyOnWriteArrayList
The Java Persistence API enables us to create the persistence layer for desktop and web applications. Java Persistence deals in the following:
1. Java Persistence API
2. Query Language
3. Java Persistence Criteria API
4. Object Mapping Metadata
ava Cryptography Architecture gives a platform and provides architecture and application programming interfaces that enable decryption and encryption.
Developers use Java Cryptography Architecture to combine the application with the security applications. Java Cryptography Architecture helps in implementing third party security rules and regulations.
Java Cryptography Architecture uses the hash table, encryption message digest, etc. to implement the security.
Spring is essentially defined as an application framework and inversion of control containers for Java. The spring framework creates enterprise applications in Java. Especially useful to keep in mind that the spring framework's central features are essentially conducive to any Java application.
A session is essentially defined as the random conversation's dynamic state between the client and the server. The virtual communication channel includes a string of responses and requests from both sides. The popular way of implementing session management is establishing a session ID in the client's communicative discourse and the server.
Objects that inherit the "Observable class" take care of a list of "observers."
When an Observable object gets upgraded, it calls the update() method of each of its observers.
After that, it notifies all the observers that there is a change of state.
The Observer interface gets implemented by objects that observe Observable objects.
Directives are instructions processed by JSP Engine. After the JSP page is compiled into a Servlet, Directives set page-level instructions, insert external files, and define customized tag libraries. Directives are defined using the symbols below:
start with "< %@" and then end with "% >"
The various types of directives are shown below:
* Include directive
It includes a file and combines the content of the whole file with the currently active pages.
* Page directive
Page Directive defines specific attributes in the JSP page, like the buffer and error page.
* Taglib
Taglib declares a custom tag library, which is used on the page.
Directives are instructions processed by JSP Engine. After the JSP page is compiled into a Servlet, Directives set page-level instructions, insert external files, and define customized tag libraries. Directives are defined using the symbols below:
start with "< %@" and then end with "% >"
The various types of directives are shown below:
Include directive
It includes a file and combines the content of the whole file with the currently active pages.
Page directive
Page Directive defines specific attributes in the JSP page, like the buffer and error page.
Taglib
Taglib declares a custom tag library, which is used on the page.
No, "this" and "super" keywords should be used in the first statement in the class constructor. The following code gives you a brief idea.
public class baseClass {
baseClass() {
super();
this();
System.out.println(" baseClass object is created");
}
public static void main(String []args){
baseClass bclass = new baseClass();
}
}
The finalize method is called the Garbage collector. For every object, the Garbage Collector calls the finalize() method just for one time.
Yes, we can execute any code, even before the main method. We will be using a static block of code when creating the objects at the class's load time. Any statements within this static block of code will get executed at once while loading the class, even before creating objects in the main method.
Enumeration or enum is an interface in Java. Enum allows the sequential access of the elements stored in a collection in Java.
The Daemon thread can be defined as a thread with the least priority. This Daemon thread is designed to run in the background during the Garbage Collection in Java.
The Externalizable interface helps with control over the process of serialization. An "externalisable" interface incorporates readExternal and writeExternal methods.
Compile-time type safety is provided by using generics. Compile-time type safety allows users to catch unnecessary invalid types at compile time. Generic methods and classes help programmers specify a single method declaration, a set of related methods, or related types with an available class declaration.