Java手机游戏编程之MIDP图形设计篇02

　　4、ChoosePieceScreen.java

　　ChoosePieceScreen是一个基于高级应用编程接口窗体的屏幕，允许游戏者选择圆或叉作为棋子。当游戏者按下OK键时，它使用MIDlet的回调方法choosePieceScreenDone来处理游戏者的选择。

　　package example.tictactoe;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.io.*;
public class ChoosePieceScreen extends List implements CommandListener
{
private static final String CIRCLE_TEXT = "Circle";
private static final String CROSS_TEXT = "Cross";
private final TicTacToeMIDlet midlet;
private final Command quitCommand;
public ChoosePieceScreen(TicTacToeMIDlet midlet) {
super("Choose your piece", List.IMPLICIT);
this.midlet = midlet;
append(CIRCLE_TEXT, loadImage("/circle.png"));
append(CROSS_TEXT, loadImage("/cross.png"));
quitCommand = new Command("Quit", Command.EXIT, 2);
addCommand(quitCommand);
setCommandListener(this);
}
public void commandAction(Command c, Displayable d) {
boolean isPlayerCircle = getString(getSelectedIndex()).equals(CIRCLE_TEXT);
if (c == List.SELECT_COMMAND) {
midlet.choosePieceScreenDone(isPlayerCircle);
}
else
// quit Command
{
midlet.quit();
}
}
private Image loadImage(String imageFile)
{
Image image = null;
try
{
image = Image.createImage(imageFile);
}
catch (Exception e)
{
// Use a 'null' image in the choice list (i.e. text only choices).
}
return image;
}
}