Introduction to Java Object Oriented Concept

Sejarah Java :
– Developed by James Gosling from Sun Microsystem and sold to Oracle in 2009.
– Agustus 1991, It was named as Oak.
– Januari 1995, Change to Java.
– Based on “Write Once, Run Anywhere (WORA)”.
– Can be run in web browser using Applet technology.

Download and install :

Most commonly application programs in JDK(Java Development Toolkit) :
–Compiler : javac
Compiling a source code(.java) into bytecode(.class)
–Interpreter : java
Execute a bytecode (.class) as application.
– Debugger : jdb
– Applet Viewer : appletviewer
– Documentation: javadoc
– Compressor: jar

Java Runtime Environment (JRE) : A software that execute Java based application.

Java Virtual Machine (JVM) : A collection of programs to execute java byte code on any computer platform.

Java byte code : A collection of machine-specific instruction that be interpreted and executed by JVM. Its length is 1 byte per instruction.

Simple Program :

public class Welcome {
public static void main(String [] args) {
System.out.println(“Welcome to Java!”);  
//pada java netbeans cara cepat buat sintaxnya : sout + tab

If Else Statement example :

* To change this template, choose Tools | Templates
* and open the template in the editor.

package belajar.pertemuan.pkg1;

import java.util.Scanner;
* @author Admin
public class BelajarPertemuan1 {

* @param args the command line arguments

public static void main(String[] args) {  

System.out.println(“Welcome to Java”); 
Scanner input = new Scanner(;
double radius,area;
double PI = 3.14;
System.out.println(“Radius : “);
radius = input.nextInt();
if (radius >= 0){
area = radius * radius * PI;
System.out.println(“The area for the circle of radius “+ radius + ” is ” + area);
System.out.println(“Negative input”);

// TODO code application logic here



Contoh if-else statement
Contoh if-else statement
Switch Case example
Switch Case example
While Statement
While Statement
Do While Statement
Do While Statement
Contoh for statement
Contoh for statement

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