Java Most Read KB Posts

An associative array links a set of keys to a set of values. In Java, associative arrays are implemented as Maps.

This will print "Arizona."

Implementing design patterns can be difficult and little sample code exists that walks you through the process. The purpose of this article is to walk through the implementation of a program that uses the Composite and Visitor design patterns. The sample project is written in the object-oriented language, Java, but it could just as easily have been written in C++.

Java String Concatenation

In Java, you use either the String concatenation + operator or StringBulder class methods such as append. Since Java compilers frequently create intermediate objects when the + operator is used and don't when StringBuilder.append is used, the append method is faster than the + operator.

In general, use the convenience of a + operator when speed is not an issue. For example, when concatenating a small number of items and when code isn't executed very frequently. A decent rule of thumb is to use the + operator for general purpose programming and then optimize the + operator with StringBuilder.append as needed.

The Java comparison operators are:

• < less than
• <= less than or equal to
• == equal to
• >= greater than or equal to
• > greater than
• != not equal

Simple syntax example of class inheritance.

An associative array links a set of keys to a set of values. In Java, associative arrays are implemented as Maps.

This will print "Arizona."

The Java compiler automatically inlines when it determines  a benefit. The use of final methods is considered a compiler hint to tell the compiler to inline the method if beneficial.

Java supports marking a full class as abstract as well as class members. A subclass must either implement the abstract members or you must declare the subclass abstract (which delays the implementation to it's subclass).

Java logical operators:

Java applets and applications both require the Java Runtime Environment (JRE) and any additional dependencies you've added.

General Info: Interface

An element of coding where you define a common set of properties and methods for use with the design of two or more classes.

Both interfaces and abstract classes are types of abstraction. With interfaces, like abstract classes, you cannot provide any implementation. However, unlike abstract classes, interfaces are not based on inheritance. You can apply an Interface to any class in your class tree. In a real sense, interfaces are a technique for designing horizontally in a class hierarchy (as opposed to inheritance where you design vertically). Using interfaces in your class design allows your system to evolve without breaking existing code.

Java Interfaces

Implementing design patterns can be difficult and little sample code exists that walks you through the process. The purpose of this article is to walk through the implementation of a program that uses the Composite and Visitor design patterns. The sample project is written in the object-oriented language, Java, but it could just as easily have been written in C++.

Java supports marking a full class as abstract as well as class members. A subclass must either implement the abstract members or you must declare the subclass abstract (which delays the implementation to it's subclass).

Literals are quoted as in "Prestwood". If you need to embed a quote use a slash in front of the quote as in \".

When calling a static method from within the same class, you don't need to specify the class name.

Java does not support multiple implementation inheritance. Each class can have only one parent class (a single inheritance path). In Java, you can use multiple interface usage to design in a multiple class way horizontally in a class hierarchy.

Simple syntax example of class inheritance.