Android : DialogFragment edited show() method in Android

I'm working with DialogFragments, I want change show(fragmentmanager,string) method with another parameters. I tried to implement new show method in dialogfragment class and call original show() methods with it but it giving exception.

MainActivity class is here;

public class MainActivity extends Activity implements CustomDialogMethods {
CustomDialog cd = new CustomDialog();   
FragmentManager fm = getFragmentManager();


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}

public void onClick(View v) {

    cd.Editshow();

}

Editshow method calling in dialogfragment's edited show method,

public class CustomDialog extends DialogFragment {

@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
    bla..
    bla..
    bla..


    return dialog;
}


public void Editshow(){

    FragmentManager fm = getFragmentManager();

    show(fm, "inform");     
}

EditShow calling original show method here..

its giving error how can fix it?

Thanks..