JAVA PROGRAMMING- OOP Concept
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The document discusses the basics of Java programming including object-oriented concepts like classes and objects. It describes classes as blueprints that define attributes and behaviors of objects. Objects are instances of classes that have both state and behavior. The document also summarizes Java features like being simple, object-oriented, robust, architecture neutral, and secure. It explains how Java works using platform-independent bytecode and the Java Virtual Machine.
JAVA PROGRAMMING- OOP Concept
- 1. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, Dwarka Institutional Area, New Delhi-75 Affiliated Institution of G.G.S.IP.U, Delhi BCA JAVA PROGRAMMING BCA 206 JAVA Basics Keywords: oop, jdk, applets
- 2. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, Dwarka Institutional Area, New Delhi-75 OOP Concept Class • A class is a blueprint or prototype • A class is a set of attributes and behaviour shared by similar object. • Classes are user defined datatype. • A class defines what data can be in an object, and what operations are performed by the methods
- 3. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, Dwarka Institutional Area, New Delhi-75 Object • It is a tangible entity • It is a instance of class • An object consists of data and functions known as methods which use or change the data. (Methods are similar to procedures or functions in other languages.) • An object is a software bundle of related variables and methods. Software objects are often used to model real-world objects you find in everyday life. • These objects have state and behavior . • A car can be modelled by an object. A car has state (how fast it's going, in which direction, its fuel consumption, and so on) and behavior (starts, stops, turns, slides, and runs into trees). • The espresso machine can be modelled as an object. It has state (water temperature, amount of coffee in the hopper) and it has behavior (emits steam, makes noise, and brews a perfect cup of java).
- 4. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, Dwarka Institutional Area, New Delhi-75 Principles • Abstraction • Encapsulation • Inheritance • Polymorphism
- 5. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, Dwarka Institutional Area, New Delhi-75 JAVA • Java technology is both a programming language and a platform.
- 6. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, Dwarka Institutional Area, New Delhi-75 • The massive growth of the Internet and the World-Wide Web leads to a completely new way of looking at development and distribution of software. • To live in the world of electronic commerce and distribution, Java technology must enable the development of secure, high performance, and highly robust applications on multiple platforms in heterogeneous, distributed networks. JAVA
- 7. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, Dwarka Institutional Area, New Delhi-75 Introduction to Java • Java is an Object oriented programming language platform. • Developed by Sun Microsystems in 1991 • Original name was Oak. • It was conceived by James Gosling. • It has built-in application programming interface (API) that can handle graphics and user interfaces and that can be used to create applications or applets. VERSIONS
- 8. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, Dwarka Institutional Area, New Delhi-75 JDK Versions • JDK 1.02 (1995) • JDK 1.1 (1996) • Java 2 SDK v 1.2 (JDK 1.2, 1998) • Java 2 SDK v 1.3 (JDK 1.3, 2000) • Java 2 SDK v 1.4 (JDK 1.4, 2002) • Java 2 5.0 (2006) • Java SE 7(mid 2010)
- 9. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, Dwarka Institutional Area, New Delhi-75 JDK Editions • Java Standard Edition (J2SE) – J2SE can be used to develop client-side standalone applications or applets. • Java Enterprise Edition (J2EE) – J2EE can be used to develop server-side applications such as Java servlets and Java ServerPages. • Java Micro Edition (J2ME). – J2ME can be used to develop applications for mobile devices such as cell phones.
- 10. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, Dwarka Institutional Area, New Delhi-75 Applets, Servlets and Applications • An applet is designed to be embedded in a Web page, and run by a browser • Applets run in a sandbox with numerous restrictions; for example, they can’t read files and then use the network • A servlet is designed to be run by a web server • An application is a conventional program
- 11. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, Dwarka Institutional Area, New Delhi-75 Features • Simple • Object oriented • Robust : Memory management and Exception handling • Architecture neutral and portable • Compiled and interpreted • Distributed • Secure • Multithreaded • High performance • Dynamic • Garbage Collected
- 12. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, Dwarka Institutional Area, New Delhi-75 Working of Java • Java solves the problem of platform-independence by using byte code. • The Java compiler does not produce native executable code for a particular machine like a C compiler would. Instead it produces a special format called byte code. • Java byte code starts with CA FE BA BE This looks a lot like machine language, but unlike machine language Java byte code is exactly the same on every platform. • This byte code fragment means the same thing on a Solaris workstation as it does on a Macintosh PowerBook.
- 13. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, Dwarka Institutional Area, New Delhi-75 Platform Working of JAVA contd.. • Java programs that have been compiled into byte code still need an interpreter to execute them on any given platform. • The interpreter reads the byte code and translates it into the native language of the host machine on the fly. • The most common such interpreter is Sun's program java (with a little j). Since the byte code is completely platform independent, only the interpreter and a few native libraries need to be ported to get Java to run on a new computer or operating system. • The rest of the runtime environment including the compiler and most of the class libraries are written in Java. • All these pieces, the javac compiler, the java interpreter, the Java programming language, and more are collectively referred to as Java.
- 14. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, Dwarka Institutional Area, New Delhi-75 • A class is a template for a Java object, and each class is compiled into a separate file called a class file. • The Java Virtual Machine itself knows nothing about the Java language, but instead understands class files and the virtual machine instruction set. • Each class file contains class constants, information about instance variables (variables created for each new object of a class), as well as method code (in bytecode format) and various symbol tables. • When the programmer asks for a new instance of a class the compiler will generate a new instruction for the virtual machine, along with a reference to the required class name. Working of JAVA contd..
- 15. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, Dwarka Institutional Area, New Delhi-75 • The virtual machine will then locate and load the appropriate class file, and create a new object according to the template the file contains. • Within each class file, all references to methods or fields of other classes are stored textually, in an area of the file known as the constant pool. • This is to ensure that classes can be recompiled with new fields or methods, without breaking older code that uses the same class. This dynamic linking helps to make Java a robust language. Working of JAVA contd..