Java Static Variables

• Java instance variables are given separate memory for storage. If there is a need for a variable to be common to all the objects of a single java class, then the static modifier should be used in the variable declaration.
• Any java object that belongs to that class can modify its static variables.
• Also, an instance is not a must to modify the static variable and it can be accessed using the java class directly.
• Static variables can be accessed by java instance methods also.
• When the value of a constant is known at compile time it is declared ‘final’ using the ‘static’ keyword.

Java Static Methods

• Similar to static variables, java static methods are also common to classes and not tied to a java instance.
• Good practice in java is that, static methods should be invoked with using the class name though it can be invoked using an object. ClassName.methodName(arguments) or objectName.methodName(arguments)
• General use for java static methods is to access static fields.
• Static methods can be accessed by java instance methods.
• Java static methods cannot access instance variables or instance methods directly.
• Java static methods cannot use the ‘this’ keyword.

Java Static Classes

• For java classes, only an inner class can be declared using the static modifier.
• For java a static inner class it does not mean that, all their members are static. These are called nested static classes in java.

Difference between static and non-static java inner class.

A static java inner class cannot have instances. A non-static java inner class can have instances that belong to the outer class.

This Core Java tutorial was posted on13/05/2008