Android创建Alert框的方法

package com.akwolf.android;import android.app.Activity;import android.app.AlertDialog;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;public class DialogActivity extends Activity { /** Called when the activity is first created. */ Button dialogBtn; @Override public void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(R.layout.main);  dialogBtn = (Button) findViewById(R.id.button1);  dialogBtn.setOnClickListener(new OnClickListener() {   @Override   public void onClick(View v) {    new AlertDialog.Builder(DialogActivity.this)      .setIcon(R.drawable.icon).setTitle("Infomation")      .setMessage("Hello World").show();   }  }); }}