Animation Program in java

Create an animation with a single line, which changes its position in a clock-wise direction. This line should produce an effect of a spinning line. In the same example give option for clock-wise or anti-clock-wise spinning. Also provide start and stop buttons to start and stop the animation. Demonstrate the animation on the screen.

Packages used:

1.      javax.swing.*     : Provides a set of "lightweight" (all-Java language) components that, to the maximum degree possible, work the same on all platforms.

2.      java.awt.*          : Contains all of the classes for creating user interfaces and for painting graphics and images.

3.      java.awt.event.*   : Provides interfaces and classes for dealing with different types of events fired by AWT components.

4.      java.lang.*            : Provides classes that are fundamental to the design of the Java programming language.

Classes used:

• Graphics : Provides classes that are fundamental to the design of the Java programming language.

·         JButton   : An implementation of a "push" button.

·         Thread    : A thread is a thread of execution in a program. The Java Virtual Machine allows an application to have multiple threads of execution running concurrently.

Logical flow of the program:

·         A class that extends JApplet and implements Runnable contains a getContentPane container JPanel which holds two buttons.

·         Since this class implements Runnable interface it defines two methods:-init() and run().

·          init() method initializes the thread.

·         Two methods are defined for clockwise spinning line and an anticlockwise spinning line.

·         Each method defines a variable “theta”.By randomly obtaining the values of x & y using Math.random() method,lines are drawn clock-wise as well as anticlockwise.

·          repaint() method is called whenever the JApplet is refreshed.

Important notes :

·         In all swing program the package that should be imported is “javax.swing.*”.

·         If in the program JApplet is inherited then the “init()” method is used to initialize the applet.

·         If in the program JFrame is inherited then the inheriting class’s constructor initializes the swing application.

1.      If super() method is called ,it should be the first line inside the constructor.

2.      Frame’s visibility and size must be set.