![11
A Simple Application
Example 1.1
//This application program prints Welcome
//to Java!
package chapter1;
public class Welcome {
public static void main(String[] args) {
System.out.println("Welcome to Java!");
}
}
.](https://image.slidesharecdn.com/javabasics-240329174916-8fc2fcad/85/Java-Standard-edition-Java-programming-Basics-for-beginner-s-11-320.jpg)
![22
Blocks
A pair of braces in a program
forms a block that groups
components of a program.
public class Test {
public static void main(String[] args) {
System.out.println("Welcome to Java!");
}
}
Class block
Method block](https://image.slidesharecdn.com/javabasics-240329174916-8fc2fcad/85/Java-Standard-edition-Java-programming-Basics-for-beginner-s-22-320.jpg)
![25
main Method
The main method provides the
control of program flow. The
Java interpreter executes the
application by invoking the main
method.
The main method looks like this:
public static void main(String[]
args) {](https://image.slidesharecdn.com/javabasics-240329174916-8fc2fcad/85/Java-Standard-edition-Java-programming-Basics-for-beginner-s-25-320.jpg)
Java Standard edition(Java ) programming Basics for beginner's
- 1. Java Programming Presented By Engr. Md. Abdul Momin (OCJA and OCJP)
- 2. 2 Programming Language Three levels of programming languages: – Machine Languages – Machine language instructions are binary coded and very low level. – Assembly Languages – Assembly language allows symbolic programming. Requires an assembler to translate assembly programs into machine programs. – High-level Languages – High-level language provides a very high conceptual model of computing. Requires a compiler to translate high-level programs into assembly programs.
- 3. 3 Java Java is a high-level object-oriented language developed by Sun Microsystems. Java’s clean design and wide availability make it an ideal language for teaching the fundamentals of computer programming.
- 4. 4 What Is Java? History Characteristics of Java
- 5. 5 History James Gosling and Sun Microsystems Oak Java, May 20, 1995, Sun World HotJava – The first Java-enabled Web browser JDK Evolutions J2SE, J2ME, and J2EE
- 6. 6 Characteristics of Java Java is simple Java is object-oriented Java is distributed Java is interpreted Java is robust Java is secure Java is architecture-neutral Java is portable Java’s performance Java is multithreaded Java is dynamic
- 7. 7 JDK Versions JDK 1.02 (1995) JDK 1.1 (1996) Java 2 SDK v 1.2 (a.k.a JDK 1.2, 1998) Java 2 SDK v 1.3 (a.k.a JDK 1.3, 2000) Java 2 SDK v 1.4 (a.k.a JDK 1.4, 2002)
- 8. 8 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.
- 9. 9 IDE Tools Forte by Sun MicroSystems Borland JBuilder Microsoft Visual J++ WebGain Café IBM Visual Age for Java Net Beans Eclipse Intelleji
- 10. 10 Getting Started with Java Programming A Simple Java Application Compiling Programs Executing Applications
- 11. 11 A Simple Application Example 1.1 //This application program prints Welcome //to Java! package chapter1; public class Welcome { public static void main(String[] args) { System.out.println("Welcome to Java!"); } } .
- 12. 12 Creating and Compiling Programs On command line – javac file.java Source Code Create/Modify Source Code Compile Source Code i.e. javac Welcome.java Bytecode Run Byteode i.e. java Welcome Result If compilation errors If runtime errors or incorrect result
- 13. 13 Executing Applications On command line – java classname Java Interpreter on Windows Java Interpreter on Sun Solaris Java Interpreter on Linux Bytecode ...
- 15. 15 Compiling and Running a Program Where are the files stored in the directory? c:example chapter1 Welcome.class Welcome.java chapter2 . . . Java source files and class files for Chapter 2 chapter19 Java source files and class files for Chapter 19 Welcome.java~
- 16. 16 Anatomy of a Java Program Comments Package Reserved words Modifiers Statements Blocks Classes Methods The main method
- 17. 17 Comments In Java, comments are preceded by two slashes (//) in a line, or enclosed between /* and */ in one or multiple lines. When the compiler sees //, it ignores all text after // in the same line. When it sees /*,
- 18. 18 Package The second line in the program (package chapter1;) specifies a package name, chapter1, for the class Welcome. Forte compiles the source code in Welcome.java, generates Welcome.class, and stores Welcome.class in the chapter1 folder.
- 19. 19 Reserved Words Reserved words or keywords are words that have a specific meaning to the compiler and cannot be used for other purposes in the program. For example, when the compiler sees the word class, it understands that the word after class is the name for the class. Other reserved words in Example 1.1
- 20. 20 Modifiers Java uses certain reserved words called modifiers that specify the properties of the data, methods, and classes and how they can be used. Examples of modifiers are public and static. Other modifiers are private, final, abstract, and protected. A public datum, method, or class can be accessed by other programs. A private datum or method cannot be accessed by other programs. Modifiers are discussed in Chapter 6, "Objects and Classes."
- 21. 21 Statements A statement represents an action or a sequence of actions. The statement System.out.println("Welcome to Java!") in the program in Example 1.1 is a statement to display the greeting "Welcome to Java!" Every statement in Java ends with
- 22. 22 Blocks A pair of braces in a program forms a block that groups components of a program. public class Test { public static void main(String[] args) { System.out.println("Welcome to Java!"); } } Class block Method block
- 23. 23 Classes The class is the essential Java construct. A class is a template or blueprint for objects. To program in Java, you must understand classes and be able to write and use them. The mystery of the class will continue to be unveiled throughout this book. For now, though, understand that a
- 24. 24 Methods What is System.out.println? It is a method: a collection of statements that performs a sequence of operations to display a message on the console. It can be used even without fully understanding the details of how it works. It is used by invoking a statement with a string argument. The string argument is enclosed within parentheses. In this case, the argument is "Welcome to Java!" You can call the same println method with a different argument to
- 25. 25 main Method The main method provides the control of program flow. The Java interpreter executes the application by invoking the main method. The main method looks like this: public static void main(String[] args) {
Editor's Notes
- #2: First Class: Introduction, Prerequisites, Advices, Syllabus Lab 1: Create a Java Project, Compile, and Run. Show syntax errors Print program Capture screen shots, and save it in Word, and print it. Homework One: Check in the class randomly.