android toast, dialog, openurl

MainActivity.java

package com.example.hello;

import android.app.Activity;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.e("log", "oncreate");
        Toast.makeText(getApplicationContext(), Math.dup("g"), Toast.LENGTH_SHORT).show();
    }

    @Override
    protected void onStart() {
    	super.onStart();
    	Log.e("log", "onstart");
    	
    	Dialog d = new AlertDialog.Builder(this).
    			setTitle("确定退出吗?").
    			setMessage("hello world").
    			setPositiveButton("确定", new DialogInterface.OnClickListener() {
    				public void onClick(DialogInterface dialog, int which) {
    					Log.e("log", "onclick ok");
    					MainActivity.this.finish();
    				}
    			}).
    			setNegativeButton("取消", new DialogInterface.OnClickListener() {
    				public void onClick(DialogInterface dialog, int which) {
    					Log.e("log", "onclick cancel");
    				}
    			}).
    			setNeutralButton("详情", new DialogInterface.OnClickListener() {
    				public void onClick(DialogInterface dialog, int which) {
    					Uri uri = Uri.parse("http://www.baidu.com");
    					Intent it = new Intent(Intent.ACTION_VIEW, uri);
    					startActivity(it);
    				}
    			}).
    			create();
    	d.show();
    }

    @Override
    protected void onPause() {
    	super.onPause();
    	Log.e("log", "onpause");
    }
    
    @Override
    protected void onResume() {
    	super.onResume();
    	Log.e("log", "onresume");
    }

    @Override
    protected void onStop() {
    	super.onStop();
    	Log.e("log", "onstop");
    }
    
    @Override
    protected void onDestroy() {
    	super.onDestroy();
    	Log.e("log", "ondestroy");
    }
}