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[Java] Simple Java Coding - Hello World!

Monday, March 3, 2008

Simple Java Coding – Hello World!

What’s wrong with the program below?

public class Main

{

void show(){

System.out.println("Hello World!");

}

public static void main (String args[])

{

int value;

show();

System.out.println(value);

}

};

The answer :

  1. the value of variable int value isn’t initialized yet
  2. Method which has static access modifier can only call method which type is static

Correction :

public class Main

{

static void show(){

System.out.println("Hello World!");

}

public static void main (String args[])

{

int value = 0;

show();

System.out.println(value);

}

};

This program will run well. Try it to make a simple java program.


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[Java] Simple Java Programming Language Keywords

Simple Java Keywords

a) new : Produce a single instans from a class dan make reference to that object.

Example :

class box {

int w,h,l;

box() {

this.w = 0;

this.h = 0;

this.l = 0;

}

};

public class BoxData {

public static void main(String[] args) {

box k = new box();

//k is a reference to an object of box class

}

}

b) private: Give a special access to a class so it can only be used by its class.

Example :

class box {

int w,h,l;

box() {

this.w = 0;

this.h = 0;

this.l = 0;

}

};

//w,h,and l variable can only be used by class Box

c) public : Give a special access to a class so it can be used by all classes.

Example :

class box {

int w,h,l;

box() {

this.w = 0;

this.h = 0;

this.l = 0;

}

};

//class box can be accessed by all classes include different package.

d) this : A special referenced symbol used in a method accessed by active object.

Example :

class box {

int w,h,l;

box() {

this.w = 0;

this.h = 0;

this.l = 0;

}

};

e) protected: Give a special access to a class so it can be used by a method which is in that class and subclass elements.

Example :

class box {

protected int w,h,l;

protected getW(){

return this.w;

}

box() {

this.w = 0;

this.h = 0;

this.l = 0;

}

};

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[Java] Introduction to Java Programming Language

Introduction to Java Programming Language

Java is a programming language originally developed by Sun Microsystems and released in 1995 as a core component of Sun's Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities. Java applications are typically compiled to bytecode which can run on any Java virtual machine (JVM) regardless of computer architecture.

The original and reference implementation Java compilers, virtual machines, and class libraries were developed by Sun from 1995. As of May 2007, in compliance with the specifications of the Java Community Process, Sun made available most of their Java technologies as free software under the GNU General Public License. Others have also developed alternative implementations of these Sun technologies, such as the GNU Compiler for Java and GNU Classpath.

HISTORY

The Java language was created by James Gosling in June 1991 for use in a set top box project. The language was initially called Oak, after an oak tree that stood outside Gosling's office - and also went by the name Green - and ended up later being renamed to Java, from a list of random words. Gosling's goals were to implement a virtual machine and a language that had a familiar C/C++ style of notation. The first public implementation was Java 1.0 in 1995. It promised "Write Once, Run Anywhere" (WORA), providing no-cost runtimes on popular platforms. It was fairly secure and its security was configurable, allowing network and file access to be restricted. Major web browsers soon incorporated the ability to run secure Java applets within web pages. Java quickly became popular. With the advent of Java 2, new versions had multiple configurations built for different types of platforms. For example, J2EE was for enterprise applications and the greatly stripped down version J2ME was for mobile applications. J2SE was the designation for the Standard Edition. In 2006, for marketing purposes, new J2 versions were renamed Java EE, Java ME, and Java SE, respectively.

In 1997, Sun Microsystems approached the ISO/IEC JTC1 standards body and later the Ecma International to formalize Java, but it soon withdrew from the process. Java remains a de facto standard that is controlled through the Java Community Process. At one time, Sun made most of its Java implementations available without charge although they were proprietary software. Sun's revenue from Java was generated by the selling of licenses for specialized products such as the Java Enterprise System. Sun distinguishes between its Software Development Kit (SDK) and Runtime Environment (JRE) which is a subset of the SDK, the primary distinction being that in the JRE, the compiler, utility programs, and many necessary header files are not present.

On 13 November 2006, Sun released much of Java as free software under the terms of the GNU General Public License (GPL). On 8 May 2007 Sun finished the process, making all of Java's core code open source, aside from a small portion of code to which Sun did not hold the copyright.

JAVA IDE

Java IDE makes us easier to make a program because we don’t need to remember the syntax and we can compile just with one click. For Java Programming Language, I suggest you to use NetBeans 6.0 and install Java Development Kit (1.6) which are free licensed. JCreator also can be used, but you must purchase a licensed. So, I suggest to use NetBeans 6.0 for learning.

You can download it here :
http://java.sun.com/javase/downloads/index.jsp


Source : en.wikipedia.org/wiki


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[WISE WORD] A Story About Frog

Friday, February 22, 2008

A Story About FROG

One day there was a competition. That was a race competition and the participants were frogs. The first frog who can climb and reach the top of the tower would be the winner. Then the competition was begun. Frogs were trying hard to climb that tower, many audiences screamed "It's impossible to reach the top of the tower because it's too high". What have the audiences said became true, many frogs were falling down. Finally just one frog left, and that frog can reach the top. He was a winner. He was succeeded lose his frightened. The audiences were confused why it could be happened. In fact the frog who was the winner was deaf so he couldn't hear what the audiences have screamed.


WHAT YOU THINK IT'S BECOME TRUE SO ALWAYS POSITIVE THINKING and WHAT YOU HEAR IS INFLUENTED YOUR MIND N POWER SO BECOME A "DEAF" IS THE BEST WAY, NEVER HEAR WORDS THAT IS NEGATIVE. BECAUSE THE NEGATIVE WORD CAN DROP OUR WISHED N OUR EFFORT...ALWAYS BELIEVES YOURSELF N NEVER SAY NEVER N IMPOSSIBLE!

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[C Programming Language] Repetition/Looping in C Programming Language

Saturday, February 16, 2008

REPETITION / LOOPING IN C PROGRAMMING LANGUAGE

Repetiton / Looping :

- A process which is done contionusly until particular value. If the limit isn’t typed, then syntax will be error because that process will be an infinite loop.

Looping which is usually used is Counting Loops. Why is it called conting loops? Because its repetition is managed by a loop control variable whose value represents a count. It is used when we can determine how many loops will be needed exactly.

The pseudocode of Counting Loops :

Set loop control variable to an initial value of 0

While loop control variable <>

... //Do something multiple times

Increase loop control variable by 1.

Three types of Counting Loops in C Programming Language :

a. FOR

Syntax :

for(initialize; test; update)

{

//Steps to perform each iteration

}

Initialize - - > initial condition of control variable

Test - - > relational expression which is a condition

Update - - > change the value of control variable

For Example :

int p = 0;

int i;

for (i=0;i<10;i++)

{

p=p+i;

}

Note :

p = p + 1 is equal with p++ and p += 1.

Flowchart :

b. WHILE (Pre Tested Loop) :

Syntax :

While(condition)

{

//Steps to perform. These should eventually

// result in condition being false

}

For Example :

int p=0;

int i=0; //initialization

while (i<10) //testing

{

p=p+i;

i++; //updating

}

Note :

If any of initialization, testing and updating are skipped, it may produce an infinite loop.

Flowchart :

c. DO-WHILE (Post Tested Loop) :

Syntax :

Do

{

//Steps to perform. These should eventually

// result in condition being false

}

While (condition);

For Example :

int i=0 //initialization

int p=0;

do

{

p=p+1;

i++; //updating

}

while (i<10); //testing

Flowchart :

Debug and Test Looping Programs :

1. Using debugger programs.

2. Use several printf statement to output the value of variables.

3. Testing the programs with try and error.

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