Using Objects in Java

Generating QR Code JIS X 0510 in Java Using Objects

To inherit from multiple classes, name each class as follows:

class className : public class1, public class2 { // Code goes here };

Understanding inheritance can be confusing enough, but trying to understand multiple inheritance can be even more complicated As a result, many C++ programmers never use multiple inheritance, so don t feel you re missing out on anything if you ignore multiple inheritance too

2: Java and C#

Understanding the C#/Java program structure Declaring variables and using operators Branching and looping statements Creating data structures and objects

he Java language was meant to build upon the success of C++, but with added safety features and true cross-platform capabilities Unlike C++, which gives programmers access to every part of the computer (along with the equal capability of screwing up every part of the computer), Java restricts access to the computer hardware Although this limits Java s flexibility, it provides greater stability and reliability of Java programs The most appealing feature of Java is its cross-platform capabilities Although porting a C++ program to run on other operating systems is possible, it s rarely easy or painless Theoretically, Java lets you write a program once and then run it on multiple operating systems, a feature often described as Write Once, Run Everywhere (or more whimsically, Write Once, Test Everywhere) Sun Microsystems developed Java and in response to Java s popularity, Microsoft developed a similar language with equivalent goals C# Like Java, C# is meant to build upon the C++ language while providing safety features to make it harder to write programs that could crash an entire computer To make programming easier, C# relies on the NET framework The idea behind NET is to shield the programmer from the complexities of the operating system Theoretically, the NET framework can be ported to other operating systems, so C# could run on any operating system that can run the NET framework Realistically, NET runs only on Windows, although programmers are trying to port the NET framework for Linux too Although C/C++ remains the most popular programming language on the planet, both Java and C# are poised as programming languages of the future Java is popular because it s platform independent, so Macintosh and Linux users can take advantage of Java C# is most popular among Windows programmers because Microsoft has positioned C# as the future programming language for Windows

Java forces object-oriented programming on you whether you like it or not Every Java program consists of a class, such as

class programname { public static void main(String args[]) { Systemoutprintln( This is a simple Java program ); } }

Because Java relies on object-oriented programming, a Java program looks more complicated than it should Basically, the main program is considered a class that has a single main function To print something, the preceding program uses a println command, which is accessed through the System class Because Java forces object-oriented thinking on you, Java programs consist of multiple classes Like Java, C# also forces object-oriented thinking on every program you write

using System; class MyClass {_static void Main() {_ConsoleWriteLine( This is a simple C# program ); } }

To write a comment in Java/C#, you have two choices First, you can use the double slash character so that anything that appears to the right of the character is a comment, such as

using System;_ class MyClass _// This is a C# comment {_static void Main() _ {_ConsoleWriteLine( This is a simple C# program );_ } }

The double slash character is handy for adding a comment to a single line If you want to write a comment over multiple lines, you can use the /* and */ characters, such as

/* This is a multiline comment to show people how easy Java can be to learn */ class programname { public static void main(String args[]) { Systemoutprintln( This is a simple Java program ); } }

Java and C#