Introduction: How to Make a Java Applet
This instructable will guide you on how to make a Java applet. The applet will output a simple message displaying "Hello World".
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Step 1: Java IDE
Download an IDE to write Java code. Skip this step if you already have one.
Note: I will use Eclipse for this instructable, but any IDE should be ok.
Step 2: Make a New Java Project
Before starting to write code, you have to make a new Java project.
Step 3: Name the Project
You can give it any name, I'll name it Hello World because that's the output we'll get.
When you finished typing the name, click on the Finish button.
Step 4: Make a New Class
Make a new class and then name it. Remember that the class name and file name must be the same.
Step 5: Import Java.awt.* and Javax.swing.*
On top of the code, type import java.awt.*; and type import javax.swing.*;
This will import the packages and the asterisk will tell the compiler to look for every class in a package.
Step 6: Extends JApplet
Type extends JApplet after the class name. This is to specify that the class is an applet and the class will inherit the functionality of an applet.
Step 7: Make the Paint Method
The paint method is where the "main" code of the applet will be written. We need a method that has an argument object from the Graphics class. The object is usually written as g. The method will be public and won't return anything.
Step 8: Add Super.paint(g); in the Paint Method
Type super.paint(g); in the paint method. This will force the applet to draw itself before drawing anything else, so that the output will be displayed correctly.
Step 9: Code to Display the Message
Now the only thing left is to write the code to display Hello World in the applet. We will call a method called drawString which will take a string, x and y values as parameters respectively. To write the string, it will be surrounded by double quotation marks; and the x and y values have to be an integer. We can choose any x,y value as long as it's not 0,0. If we choose 0,0; then the string will not be visible, as it will be above the visible area.
I will choose as x value 20 and y value 20.
The code will be: g.drawString("Hello World",20,20);
Note: There are no negative values for x and y.
Step 10: Output
Finally, click on the Run button and you will see an applet viewer window with the string Hello World.
Congratulations! You made an applet.