设置dialog显示，自定义时间到后dialog消失

public class  MyDialog extends Dialog {
private int FLAG_DISMISS = 1;
private boolean flag = true;

public MyDialog(Context context) {
super(context);
setTitle("自动消失对话框测试！");
}

@Override
public void show() {
super.show();
mThread.start();
}

@Override
public void dismiss() {
super.dismiss();
flag = false;
}

private Thread mThread = new Thread(){
@Override
public void run() {
super.run();
while(flag){
try {
Thread.sleep(2000);
Message msg = mHandler.obtainMessage();
msg.what = FLAG_DISMISS;
mHandler.sendMessage(msg);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
};

private Handler mHandler = new Handler(){
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
if(msg.what == FLAG_DISMISS)
dismiss();
}

};

}

自定义一个定时器：
public static class TimeCount extends CountDownTimer
{
public TimeCount(long millisInFuture, long countDownInterval)
{
super(millisInFuture, countDownInterval);
}
@Override
public void onFinish() {
// TODO Auto-generated method stub
alertDialog.dismiss();//alertDialog是你的对话框
}
}
然后在你自己的程序中AlertDialog部分中添加：
TimeCount timer = new TimeCount(7000, 1000);//具体时间自定
timer.start();