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Revision as of 04:29, 8 August 2013 by hamishwillee (Talk | contribs)

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Canvas Loading Bar in Java ME

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Created: jappit (30 Apr 2008)
Last edited: hamishwillee (08 Aug 2013)

A simple loading bar to be used on Canvas when doing long operations. You can see a live preview here: Canvas Loading bar emulator

J2me loading bar.png

We'll start defining some instance variables, that we'll use within our code:

public long stepInterval = 250L;
public int width = 0;
public int height = 0;
int padding = 0;
int color = 0x000000;
int squares = 0;
int squareWidth = 0;
int currentSquares = 0;
Timer stepTimer = null;

Now the bar constructor, with its arguments:

  • bar size (width and height)
  • padding between squares
  • number of squares to be used
  • squares color
public LoadingBar(int width, int height, int padding, int squares, int color)
this.width = width;
this.height = height;
this.squares = squares;
this.color = color;
this.padding = padding;
this.squareWidth = (width - padding) / (squares) - padding;

Paint method is quite straightforward:

public void paint(Graphics g)
for(int i = 0; i < currentSquares; i++)
g.fillRect(i * (squareWidth + padding), 0, squareWidth, height);

Finally, the animation logic, where we'll use a Timer, and expose start() and stop() methods to control Bar animation:

public void start()
stepTimer = new Timer();
stepTimer.schedule(new TimerTask()
public void run()
stepInterval, stepInterval
public void stop()
void step()
currentSquares = (currentSquares + 1) % (squares + 1);
This page was last modified on 8 August 2013, at 04:29.
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