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Fundamental Object-Oriented Concepts |
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An interface can extend any number of interfaces; a class can implement any number of interfaces. However, a class cannot extend more than one class. |
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Fundamental Object-Oriented Concepts |
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According to the JavaBean naming standards, if the property name is 'x' and the type is Type, the accessor(getter) method is in the form:
public Type getX()
and the mutator(setter) method is in the form:
public void setX(Type newValue)
However, a boolean property may also use the following convention for its accessor(getter) method.
public boolean isX()
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UML Representation of Object-Oriented Concepts |
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In UML, abstract types and methods are represented in italics. In the case of interfaces, the additional requirement is that the word <> is added above the interface name.
For example, Vehicle is an interface that defines a method drive().
<<interface>>
Vehicle
drive() |
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UML Representation of Object-Oriented Concepts |
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Associations between 2 classes are shown as solid lines between classes. The navigability of an association is expressed as an open arrow at the end of the association line. |
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Java Implementation of Object-Oriented Concepts |
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The visibility rules for access modifiers are as follows:
- private - can only be accessed from inside the class.
- No modifier- the members have default access level, that is, they can be accessed only by other classes in the same package.
- protected - can only be accessed by classes in the same package or subclasses of this class.
- public - can be accessed by any other class.
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Java Implementation of Object-Oriented Concepts |
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Polymorphism refers to "many forms". It allows you to use a supertype (a superclass or an interface) reference to refer to one of its subtypes. |
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Algorithm Design and Implementation |
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The enhanced for loop is in the form:
for (Type Identifier: Expression) Statement
The expression must be either an array or a collection. It provides a simple way for iteration of the loop.
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Algorithm Design and Implementation |
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The substring method returns a portion of the String on which it is invoked. It is of 2 forms as given below.
public String substring(int beginIndex);
- Returns all the characters from the specified beginIndex till the end of the String.
public String substring(int beginIndex, int endIndex);
- Returns all the characters from the specified beginIndex till endIndex - 1.
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Java Development Fundamentals |
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The java.util package contains the collections framework, legacy collection classes, event model, date and time facilities, internationalization, and miscellaneous utility classes such as a string tokenizer, a random-number generator, and a bit array. |
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Java Development Fundamentals |
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The -d option of javac helps you to set the destination directory where the compiler must place the class files. If a class is specified in a package, javac puts the class file in a subdirectory reflecting the package name, creating directories as needed. However the main destination directory must exist and cannot be created. |
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Java Platforms and Integration Technologies |
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J2ME (Java 2 Micro Edition) consists of 3 software layers - JVM, Configuration, and Profile. The configuration acts as an interface between the VM and the profile. A profile defines the set of APIs available for a particular family of devices. |
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Java Platforms and Integration Technologies |
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Java Naming and Directory Interface (JNDI) provides a unified interface to Java applications for lookup and directory services. |
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Client Technologies |
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Abstract Window Toolkit (AWT) components use native peer components, so they are considered to be heavy weight as compared to swing components which are pure Java components. |
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Client Technologies |
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JavaScript can be used in web pages to provide form manipulations such as client side validations, event handling and some visual effects. |
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Server Technologies |
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In the business tier, a message-driven bean (MDB) allows J2EE(Java 2 Enterprise Edition) applications to receive JMS (Java Messaging Service) messages asynchronously, that is, senders are independent of receivers. |
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Server Technologies |
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Simple Object Access Protocol (SOAP) is a XML-based platform-neutral protocol to send structured messages. |
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