無法啓動活動ComponentInfo java.lang.IllegalStateException：的onCreate（）之前系統服務不提供給活動

Question

我想看看用戶是否具有互聯網連接時，應用程序啓動：

package nco.supp; 

import android.app.Activity; 
import android.app.AlertDialog; 
import android.content.Intent; 
import android.os.Bundle; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import nco.supp.Status; 
import nco.supp.Register; 

public class ncosuppActivity extends Activity { 
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 

     NetworkManager networkManager = new NetworkManager(); 
     if (!networkManager.haveNetworkConnection()) { 

      AlertDialog.Builder dlgAlert = new AlertDialog.Builder(this); 
      dlgAlert.setPositiveButton("Ok", null); 

     } 

     Button loginButton = (Button) findViewById(R.id.loginButton); 
     loginButton.setOnClickListener(new OnClickListener() { 

      @Override 
      public void onClick(View v) { 
       startActivity(new Intent(ncosuppActivity.this, Status.class)); 

      } 
     }); 

     Button registerButton = (Button) findViewById(R.id.registerButton); 
     registerButton.setOnClickListener(new OnClickListener() { 

      @Override 
      public void onClick(View v) { 
       startActivity(new Intent(ncosuppActivity.this, Register.class)); 

      } 
     }); 
    } 
} 

---

package nco.supp; 

import android.app.Activity; 
import android.content.Context; 
import android.net.ConnectivityManager; 
import android.net.NetworkInfo; 

public class NetworkManager extends Activity{ 


    public boolean haveNetworkConnection() { 
     boolean haveConnectedWifi = false; 
     boolean haveConnectedMobile = false; 

     ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE); 
     NetworkInfo[] netInfo = cm.getAllNetworkInfo(); 
     for (NetworkInfo ni : netInfo) { 
      if (ni.getTypeName().equalsIgnoreCase("WIFI")) 
       if (ni.isConnected()) 
        haveConnectedWifi = true; 
      if (ni.getTypeName().equalsIgnoreCase("MOBILE")) 
       if (ni.isConnected()) 
        haveConnectedMobile = true; 
     } 
     return haveConnectedWifi || haveConnectedMobile; 
    } 


} 

我收到此錯誤：

java.lang.RuntimeException: Unable to start activity ComponentInfo{nco.supp/nco.supp.ncosuppActivity}: 
java.lang.IllegalStateException: System services not available to Activities before onCreate() 

任何想法？

Answer 1

您正試圖在沒有onCreate()方法的情況下在類Activity中創建方法，這是錯誤的。只需在您的MainActivity內創建一個方法爲

private boolean checkConnectivity() { 
     ConnectivityManager manager = (ConnectivityManager) 
          getSystemService(Context.CONNECTIVITY_SERVICE); 
     return manager.getActiveNetworkInfo() != null && manager. 
          getActiveNetworkInfo().isConnectedOrConnecting(); 
    } 

這應該會起作用。