android source not found解决思路

android source not found
我做了一个关于android定时器的东西，就是每秒让textviewi刷新一次。代码如下：
package com.timetry;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.widget.TextView;

import java.util.Timer;
import java.util.TimerTask;

public class TimetryActivity extends Activity {
  /** Called when the activity is first created. */
private String tag = "@@@";
Timer timer = new Timer();
private int i = 0;
private TextView text = null;
private Handler handler = new Handler()
{
@Override
public void handleMessage(Message msg)
{
// TODO Auto-generated method stub   
super.handleMessage(msg);
int msgId = msg.what;
Log.e(tag, msgId + "");
switch (msgId)
{
case 1:
text.setText("one more per second" + i);
i++;
break;
default:
break;
}
}
};
  @Override
  public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
  text = (TextView)findViewById(R.id.text);
  setTimerTask();
  }
  @Override
  protected void onDestroy()
  {
  super.onDestroy();
  timer.cancel();
  }
  private void setTimerTask()
  {
  timer.schedule(new TimerTask()
  {
  @Override
  public void run()
  {
  Message message = new Message();
  message.what = 1;
  handler.sendMessage(message);
  }
  }, 0, 1000);

  }
   
}
上面的代码可以运行。我改了下代码：如下
package com.timetry;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.widget.TextView;

import java.util.Timer;
import java.util.TimerTask;

public class TimetryActivity extends Activity {
  /** Called when the activity is first created. */
private String tag = "@@@";
Timer timer = new Timer();
private int i = 0;
private TextView text = null;
  @Override
  public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
  text = (TextView)findViewById(R.id.text);
  setTimerTask();
  }
  @Override
  protected void onDestroy()
  {
  super.onDestroy();
  timer.cancel();
  }
  private void setTimerTask()
  {
  timer.schedule(new TimerTask()
  {
  @Override
  public void run()
  {
  text.setText("one more per second" + i);
  i++;
  }
  }, 0, 1000);

  }
   
}
这样就不行了，运行的时候没显示，调试的时候会报 source not found。
这是怎么回事，我改的代码有问题吗？

------解决方案--------------------
mWiFiManager01 = (WifiManager) TimetryActivity.this.getSystemService(Context.WIFI_SERVICE);
mWiFiManager01.startScan();