@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    final AlertDialog.Builder alert = new AlertDialog.Builder(this);
    final EditText input = new EditText(this);
    alert.setView(input);

    alert.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int whichButton) {
            Toast.makeText(getApplicationContext(), value,
                    Toast.LENGTH_SHORT).show();
        }
    });

    alert.setNegativeButton("Cancel",
            new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int whichButton) {
                    dialog.cancel();
                    Toast.makeText(getApplicationContext(), value,
                    Toast.LENGTH_SHORT).show();


                }
            });

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

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            alert.show();
        }
    });
}