Android--ProgressDialog用法

.java代码如下：

package org.lxh.demo;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnFocusChangeListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class Hello extends Activity {
	public ProgressDialog myDialog = null;

	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState); // 生命周期方法
		super.setContentView(R.layout.main); // 设置要使用的布局管理器
		Button btn = new Button(this);
		this.setContentView(btn);// 全屏幕显示按钮
		btn.setText("请按下我运行程序...");
		btn.setOnClickListener(new OnClickListenerImpl());

	}

	private class OnClickListenerImpl implements OnClickListener {

		public void onClick(View arg0) {
			CharSequence strDialogTitle = "请稍等片刻...";
			CharSequence strDialogBody = "正在运算中...";
			myDialog = ProgressDialog.show(Hello.this, strDialogTitle,
					strDialogBody);
			new Thread() {

				@Override
				public void run() {
					try {
						sleep(3000);
					} catch (InterruptedException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
					myDialog.dismiss();
				}

			}.start();

		}

	}
}