Using classes in android - working with Context and helper classes

I am still newbie to android, please could someone help.

I want to use methods from the Net class as follows:

package com.test;

import android.app.Activity;
import android.os.Bundle;
import android.view.Window;
import android.widget.TextView;

public class MyApp extends Activity {

  /** Called when the activity is first created. */
  private Net wifi;

  TextView textStatus;    

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    requestWindowFeature(Window.FEATURE_NO_TITLE); 
    setContent开发者_如何学PythonView(R.layout.main);

    wifi=new Net(this);
    textStatus = (TextView) findViewById(R.id.text); 
    textStatus.append("Your online status is ");

    if (wifi.isOnline()) {
      textStatus.append("online "+wifi.getInfo());
    } else {
      textStatus.append("offline "+wifi.getInfo());
    }
  }
}

and my Net class:

import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.net.wifi.WifiInfo;
import android.net.wifi.WifiManager;
import android.os.IBinder;

public class Net {
  WifiManager wifi;
  ConnectivityManager cm;
  NetworkInfo netInfo;

  public Net (Context ctx) {
    cm = (ConnectivityManager) ctx.getSystemService(ctx.CONNECTIVITY_SERVICE);
    netInfo = cm.getActiveNetworkInfo();
    wifi = (WifiManager) ctx.getSystemService(Context.WIFI_SERVICE);
  }

  public boolean isOnline() { 
    netInfo = cm.getActiveNetworkInfo();

    if (netInfo != null && netInfo.isConnectedOrConnecting()) {
      return true;
    } else {
      return false;
    }
  }

  public NetworkInfo[] getName() {
    NetworkInfo[] name=cm.getAllNetworkInfo();
    return name;    
  }

  public String getInfo() {
    // Get WiFi status
    WifiInfo info = wifi.getConnectionInfo();
    return info.getSSID().toString();
  }
}

I believe I should not be extending my Net class with Activity? I am getting source not found error when running the app.

I believe I should not be extending my Net class with Activity?

Correct!

Your Net class is simply a helper so can be simply defined as:

public class Net {

  public Net (Context ctx) {
    cm = (ConnectivityManager) ctx.getSystemService(Context.CONNECTIVITY_SERVICE);
    netInfo = cm.getActiveNetworkInfo();
  }

  // Your other methods here...
}

When you create your wifi object, use wifi = new Net(this);

The Activity class in Android is used to provide a UI framework for visual/interactive elements such as buttons, textviews etc. etc. - basically anything the user needs to interact with. This isn't appropriate for your Net class.