Java Basics

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Basically, the JavaTM language is a object oriented programming language that is designed for making Applications and Applets that are removed from the underlying hardware so they can be moved to any operating System that has a Java Virtual Machine JVM.

Now the Java Virtual Machine is not written in the Java language, but is written in a lower level language, such as C or C++. The JVM handles the low level details so that Java programmers do not have to deal with those issues. All JVMs of all platforms must conform to the specifics of the Java language set forth by, the maker of the Java technology. Currently There are full Java 6 platform JVMs for four platforms: WindowsTM, Linux, SolarisTM Unix, and Mac OS XTM. Mac's JVM is built into the Operating System. The other JVMs can be downloaded from

On each of these JVMs, Java code should produce the same result for a same Java applications and applets. The JVMs on the other hand, are programmed in many different ways in different low level languages to achieve this uniformity across platforms.

This gives the Java Programmer the ability to program in code to do his specific tasks, unhindered by those low level concerns which is why the Java language can be learned faster than C or C++ and the Java programmer is a lot more efficient and faster in developing products than is C or C++ contemporaries.

The Java documentation (javadoc) describing all classes and their methdod can be found at for the latest jdk version of the Java Platform, version 1.6 (This version is also called 'MustangTM'). For info on the javadoc command for making Java documentation for your Java classes and libraries see javadoc example.

One Advantage the Java language has that makes it so powerful is that it is strongly typed. That means that all data in the form of Objects and primitive types are of exact types, like char, byte, int, String, StringBuffer. This makes java powerful because it gives the programmer absolute control over the form that the data is in. Click here for a list of primitive types.

In many other languages, type is variable, depending on how the data unit is used. But not in the Java language. In the Java language, every variable name is of a specific type: either of a primitive type or an Object.

Also, there are a set of words that cannot be used as variable names, because they have a special meaning in the language, such as 'return' and 'void'. Click here to view these keywords, which include the primitive types.

The Java language has single inheritance from child class to super class, and multiple inheritance from interfaces. This is an improvement over C++'s attempt at object-oriented programming, which has multiple inheritance from child class to super classes. Inheritance is covered in the Inheritance page.

*OracleTM and JavaTM are registered trademarks of Oracle and or its affiliates. Other names may be trademarks of their respective owners.*