ProgressDialog

 protected void onCreate(Bundle savedInstanceState) {  
      button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                openProcessDialog(true);
                Intent i = new Intent();
                i.setClass(MainActivity.this, MyFaxMainPage.class);
                startActivity(i);

            }
        });
......
}

 private void openProcessDialog(boolean value) {

        if (value) {
            progressDialog = new ProgressDialog(MainActivity.this);
            progressDialog.setIndeterminate(false);
            progressDialog.setCancelable(false);
            progressDialog.setMessage("Preparing EFax ducument");
            progressDialog.show();
        } else {
            if (progressDialog != null && progressDialog.isShowing()) {
                progressDialog.dismiss();
            }
        }

    }

 @Override   //dismiss,when back to mainpage
    protected void onStop() {
        super.onStop();
        openProcessDialog(false);
        progressDialog = null;
    }