Programming Step by Step

Other modifiers for data members Besides the visibility modifier public, we can also use modifiers static and final. Although we can use th...

(a) abstract This is the only modifier other than visibility modifiers, which can be used with interface. Interfaces just specify the metho...

Besides visibility modifiers, we can also use following modifiers before a top-class: (a) abstract, and (b) final (a) abstract A class ca...

The only member accessibility/visibility modifier that can be used with data members and methods of an interface is public .  The public is...

By specifying member accessibility modifiers a class can control what information is accessible to clients (i.e. other classes). These modi...

public default (package) accessibility

Introduction Modifiers are Java keywords that give the compiler information about the nature of code, data, classes or interfaces. For exam...

This is quite easy to do, just define a sub class of Exception/Error class. Your sub-classes do not need to actually implement anything. It...

finally creates a block of code that will be executed after a try/catch block has completed and before the code following the try/catch blo...

Example: Normally built-in exceptions are thrown by the JVM but user can also create and throw any exception although this is normally not ...

Example: This program also handles the Checked Exceptions. The following program takes names of two files as input and copies the file spec...

Example: This example demonstrates the action taken by the default error/exception handler when an exception/error occurs and is not handl...

It is possible for your program to throw an exception/error explicitly, using the throw statement. The general form of throw is shown here:...

If a method is capable of causing an exception that it does not handle, it must specify this behavior so that callers of the method can gua...

Exceptions can be categorized in two types: Unchecked Exception Checked Exception Checked Exception If it is must to check an excepti...

Java exception/error handling is managed via five keywords: try, catch, throw, throws, and finally. The general form of an exception-handli...

Exceptions/Errors are also objects in Java. Root class of all exception/error classes is the Throwable class, which is an immediate sub-c...

An exception/error is an abnormal condition that breaks/disrupts the normal program flow. The abnormal condition occurs at run-time i.e. du...

Example: This example is covered when discussing abstract classes. The example is modified such that instead of declaring Shape class as an...

Interface can be declared as abstract but it is superfluous and seldom done. Since interfaces are meant to be implemented by classes, inte...

The variables defined in an interface are implicitly public, static and final as discussed earlier. The variables can be accessed just like...

One interface can inherit another by use of keyword extends. The syntax is the same as for inheriting classes. When a class implements an i...

Once an interface has been defined, one or more classes can implement that interface. To implement an interface, include the implements cla...

The general form of an interface is like class as shown below. modifiers interface <interfac_name> { modifiers return_type method1(pa...

The purpose of the interface is to separate a class’s interface from its implementation. Interface just defines what a class must do withou...

We discuss this concept with reference to previous example. Given that packages exist and are a good mechanism for compartmentalizing diver...

Classes and packages are both means of encapsulating and containing the name space and scope of variables and methods. Packages act as cont...

If no package name is specified in any java file then the class is part of the unnamed package. This requires that every class must have a ...

There are situations in which you will want to define a super class that declares the structure of a given abstraction without providing a ...