No enclosing instance of type ContactsXmpp is acce

问题:

this is the class i am using

public class ContactsXmpp extends SherlockFragmentActivity {

private static Context ctx;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.contacts_xmpp_sip);

    ctx = this;
}   

i am getting error when i call asynctask from this method. this is the error No enclosing instance of type ContactsXmpp is accessible. Must qualify the allocation with an enclosing instance of type ContactsXmpp (e.g. x.new A() where x is an instance of ContactsXmpp).

private static void alert( String str, final String name ) {

    AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(ctx);       
    alertDialogBuilder.setMessage(str + ": " + name);
    alertDialogBuilder.setCancelable(false)
    .setPositiveButton("Yes",new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog,int id) {                 
            Subscription(name);          
            new ColorsXMPP_AfterLogin().execute();     ///** error getting here..                                
        }
    }); 

    alertDialogBuilder.setNegativeButton("No", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            unSubscribe(name);
        }           
    });

    AlertDialog alertDialog = alertDialogBuilder.create();       
    alertDialog.show();         
}    

Asynctask here

public class ColorsXMPP_AfterLogin extends AsyncTask<AfterLogging, Void, Void> {

    private ProgressDialog _dialog;

    @Override
    protected void onPreExecute() {          
        super.onPreExecute();            
        Log.e(TAG, " GmailXMPP_AfterLogin onPreExecute" );
    }

    @Override
    protected void onPostExecute(Void feed) {
        //ProgressBar_hide();       
        _dialog.dismiss();
        Log.e(TAG, " GmailXMPP_AfterLogin onPostExecute" );        
    }

    @Override
    protected Void doInBackground(AfterLogging... arg0) {

        Log.e(TAG, " GmailXMPP_AfterLogin doInBackground" );

        return null;
    }
 }

回答1:

You can't instantiate the ColorsXMPP_AfterLogin class in the static method of alert(I'm assuming that both are in the ContactsXmpp activity). The problem is that ColorsXMPP_AfterLogin is declared as being an inner class and inner classes need an instance of the enclosing class to be created(they require this connection). In the static alert method you don't have this instance so the compiler throws that error. You have several options to solve the problem, the one I would recommend is to either make ColorsXMPP_AfterLogin as a nested class in ContactsXmpp(declared like public static class ColorsXMPP_AfterLogin...) or completely move it in its own java file(if you need a connection to the Activity's Context simply pass a reference to that ctx in the AsyncTask's constructor).

You could also use the ctx variable to create the instance of ColorsXMPP_AfterLogin like:

ctx.new ColorsXMPP_AfterLogin();