gistfile1.txt

in my project on splash screen load i am checking if url is rechable in thread and when it is not reachable show alert screen
for that i am using 

@Override 
protected void onCreate(Bundle savedInstanceState) { 

setContentView(R.layout.activity_splash); 
super.onCreate(savedInstanceState); 


Thread t =new Thread() 
{ 
@Override 
public void run() { 
try 
{ 
sleep(2000); 
if (isURLReachable(SplashActivity.this)) { 
Log.d("server", "reachable"); 
} 
else 
{ 
Log.d("server","unreachable"); 
showAlertDialog(); 

}} 
catch (InterruptedException e) 
{ 
e.printStackTrace(); 
} 
super.run(); 
} 

}; 
t.start(); 
}

/*************/
protected void showAlertDialog() 
{ 
AlertDialog.Builder alertdialog=new AlertDialog.Builder(this); 
alertdialog.setMessage("Server is not reachable.Please try Again."); 
alertdialog.setCancelable(false); 
alertdialog.setPositiveButton("OK",new DialogInterface.OnClickListener(){ 
@Override 
public void onClick(DialogInterface dialogInterface, int id) { 
finish(); 
dialogInterface.cancel(); 
} 
}); 
alertdialog.show(); 
}
but my application is getting crashed
please suggest me