java - Call AlertDialog from another class -

i have decided place dialogs in notify class.

however when attempt call dialog, application crashes

this notify class:

public class notify extends activity {   public void  errorhandler(string title, exception e) {     eh(title, e); }  public void  messagebox(string title, string details) {     alertdialog(title, details); }      //*************************************************************** //display error dialog. //**************************************************************** private void eh(string method, exception e) {     log.e("firstdroid exception", method + " : " + e.getmessage());      e.printstacktrace();      alertdialog alertdialog;     alertdialog = new alertdialog.builder(this).create();     alertdialog.settitle(method);     alertdialog.setmessage(e.getmessage());     alertdialog.seticon(r.drawable.quiticon);     alertdialog.setcanceledontouchoutside(true);     alertdialog.show(); }   //************************************************************* //generic dialog messages user //************************************************************* private void alertdialog(string title, string message) {            log.i("message", message);      alertdialog.builder messagebox;     messagebox = new alertdialog.builder(null);     messagebox.settitle(title);     messagebox.setmessage(message);     messagebox.seticon(r.drawable.infoicon);     messagebox.setneutralbutton("ok", null);     messagebox.setcancelable(false);     messagebox.show(); } 

i create new instance of notify, , call messagebox, so:

notify notify = new notify();  notify.messagebox("test title", "test message"); 

android.app.alertdialog.builder.builder(context context), u need transfer or applicationcontext eh() method,

alertdialog = new alertdialog.builder(this).create();

for another, why u create 1 activity , call public method? what's meaning, hava no idea it.