The first program you will make in Java, gives the output HELLOWORLD

or as you should say in the programming language: prints, the words “Hello World”.

The program HelloWorld, is traditionally used to introduce new programmers to a programming language. Because at this moment you haven’t had any theory. It will be really hard to know what you’re doing. Therefore, I explain it first by creating HelloWorld in the easy way. Later on, we will build the program again, and then you should you know what is going on.

This should work in the way, that you press run and the computer says HelloWorld

in java

1.

start, by copying the structure.
Change the:

Package Name package HelloWorld;
Class Name (on 2 places) class HelloWorld {         new HelloWorld().start();	here and here

STRUCTURE:

package HelloWorld;

class HelloWorld {

	void start(){
	}
	
	public static void main(String[] args) {
		new HelloWorld().start();
	}
}

2.

For now we are only going to write in the start method:

In the start method we are going to say:

Getting output could be done in different ways. Most common for this program, is to use the CONSOLE.

System.out.println("Hello World")

3.

In Java it is not possible to run a single line of code without using any structure. Therefore, we have to combine the:

• structure
• print line

package P;

public class HelloWorld {

	void start() {
		System.out.println("HELLOWORLD");
	}
	
	public static void main (String [] args) {
		new HelloWorld().start();
	}

}

extra

System.out.println(“..”) is allowed in the Java, but when you are writing bigger programs it is easier and shorter to only use: out.println(” .. “). Therefore,

1. Add this line of code in the start method:

PrintStream out = new PrintStream(System.out);

2. You will get an error:

Just click on it:

3. and dubbel-click on Import ‘PrintStream’ (java.io); eclipse automatically adds the code on the right place:

import java.io.PrintStream;

Now, your code looks like this:

package HelloWorld;

import java.io.PrintStream;

class HelloWorld {

	void start() {
		PrintStream out = new PrintStream(System.out);
		out.printf("Hello World");
	}

	public static void main(String[] args) {
		new HelloWorld().start();
	}
}

4. Press run

BACK to the theory

because you created a programming without knowing what you were actually doing we first gonna learn some theory!

!CLICK HERE!