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Learn about mouse and keyboard input with the Slick2D game library.

Table of contents


This module is one in a collection of modules designed to teach you about the anatomy of a game engine.

Although the modules in this collection will concentrate on the Java game library named Slick2D, theconcepts involved and the knowledge that you will gain is applicable to different game engines written in different programming languages as well.

The purpose of this module is to explain some aspects of mouse and keyboard input.

Viewing tip

I recommend that you open another copy of this module in a separate browser window and use the following links to easily find and view the imagesand listings while you are reading about them.


  • Figure 1 . Output from the program named Slick0170.java.


  • Listing 1 . Beginning of the update method.
  • Listing 2 . Test for up or down movement.
  • Listing 3 . Test for collisions with the edges.
  • Listing 4 . Get and save mouse coordinates.
  • Listing 5 . Source code for the program named Slick0170.


Most games and many simulations are interactive. By that I mean that they require user input to perform according to their design.

I will present and explain a program in this module that allows the user to cause a ladybug sprite (see Figure 1 ) to move inside the game window by pressing the arrow keys on the keyboard or the left and right mousebuttons. (The mouse pointer must be inside the game window for the mouse buttons to move the sprite.)

Figure 1 . Output from the program named Slick0170.java.
Missing image.


Pressing the right arrow key or the right mouse button causes the sprite to move to the right.

Pressing the left arrow key or the left mouse button causes the sprite to move to the left.

Pressing the up arrow key causes the sprite to move up, and pressing the down arrow key causes the sprite to move down.

The sprite cannot be caused to move up or down (in this program) by pressing mouse buttons.

What you have learned

In the previous module, you learned about using the draw , drawCentered , and drawFlash methods of the Image class.

What you will learn

In this module, you will learn how to use the following methods of the Input class to get input from the user:

  • isKeyDown
  • isMouseButtonDown
  • getMouseX
  • getMouseY

General background information

Modern computer programs fall generally in one or a combination of two categories:

  • Event driven programs
  • Polled programs

Analogy for an event-driven program

I like to think of event-driven programs as being somewhat analogous to the way that we normally drive our cars. When we come to a red stoplight, we removeour foot from the gas pedal, press the brake pedal to stop, and allow the motor to idle, thus consuming minimal fuel. (If we don't have an automatic transmission, we will probably also disengage the clutch and move the gearshiftleaver to the neutral position.)

Questions & Answers

what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
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Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Anatomy of a game engine. OpenStax CNX. Feb 07, 2013 Download for free at https://legacy.cnx.org/content/col11489/1.13
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