Java

Java is a powerful object-oriented language that is fun to use para sa mga begginer lalo na sa mga may karanasan na sa paggawa ng isang substantial information system. Maaari itong maging language of choice sa pag-implement ng Internet-based o Internet based applications as well as software for devices that communicate over networks.

Nagcoconsist ang Java ng several parts: an environment, the language, the Java Applications Programming Interface (API), and various class libraries. Normally, java programs have five phases to be executed. ito ang edit, compile, load, verify and execute.

Experienced programmers sometimes take pride in being able to create some weird, contorted, convoluted usage of a language. This is a poor programming practice. It makes programs more difficult to read, more likely to behave strangely, mas mahirap din itong itest at idebug, and more difficult to adapt to changing requirements. Also maaaring magrun ang any program written in Java sa iba’t ibang unit o computer. The most problem with the early versions of Java is that the programs execute interpretively on the client’s machine. Iniinterpret nito ng isa-isa line by line compared to fully compiled code machine.

Here is a simple program for printing a line of text.

public class Welcome1

{

public static void main( String args[] )

{

     System.out.println(“Welcome to Java Programming!”);

}

}

Tapos ito yung magiging output: Welcome to Java Programming!

            Sa pagcocompile ng isang Java program, we open a command window, baguhin ang directory kung saan nakastore ang program tapos itype ang java Welcome1.java. Kung ang iyong program ay hindi nagco-contain ng any syntax error, the preceding command creates a new file na tinatawag na Welcome1.class containing the Java byte codes na magre-represent ng application. Ang byte codes na ito ay syang iiinterpret ng Java interpreter kapag iniexecute na natin ang program by typing java Welcome1.

            Kapag nagkaroon ng isang syntax error, maaring wala ito sa line na inindicate ng error messages. First, icheck muna ang line na inindicate ng error messages at kapag hindi ito ang nagco-contain ng error, sunod naming tingnan para icheck ay ang preceding lines ng program.

Every program ng Java ay nagco-consist ng atleast one class definition that is defined by the programmer. Ang keyword na class ang nag-iintroduce ng class definition ng Java na sya namang sinusundan ng class name (Welcome1). Keywords are always spelled with all lowercase letters.

Laging tandaan na ang Java ay case sensitive. Ang hindi paggamit ng proper uppercase at lowercase letters for an identifier ay maituturing na syntax error. You should always begin a class name with a capital first letter. When reading Java program, laging tingnan ang identifier na nagsisimula sa capital letters. These normally represent Java classes. Avoid using identifiers containing dollar sign ($) as these are often used by the compiler to create identifier names. public static void main( String args[] ) --- ito ay part ng every Java application. Automatically java applications begin executing at main. Ang parenthesis after main ay nag-iindicate na ang main ay isang program method. The left brace begins the body of the method definition then the right brace must end the method definition’s body. System.out.println(“Welcome to Java Programming!”); --- ito naman ang nag-iinitiate sa computer to print the string of characters contained between the double quotation marks. Maaari din tawaging character string, a message or a string literal ang string. System.out is known as the standard output object. It allows Java applications to display strings and other types of information in the command window from which the Java application is executed. System.out.println --- its argument in the parenthesis and the semicolon is called a statement. Kailangang ang every statement must end with a semicolon o ang tinatawag na statement terminator. Kapag naexecute na ito, it now displays the message (Welcome to Java Programming!) in the command window.

by: Camille Abigail M. Rollan

200910643