editText
is a part of alertDialog
layout so Just access editText
with reference of alertDialog
EditText editText = (EditText) alertDialog.findViewById(R.id.label_field);
Update:
Because in code line dialogBuilder.setView(inflater.inflate(R.layout.alert_label_editor, null));
inflater
is Null.
update your code like below, and try to understand the each code line
AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(this);
// ...Irrelevant code for customizing the buttons and title
LayoutInflater inflater = this.getLayoutInflater();
View dialogView = inflater.inflate(R.layout.alert_label_editor, null);
dialogBuilder.setView(dialogView);
EditText editText = (EditText) dialogView.findViewById(R.id.label_field);
editText.setText("test label");
AlertDialog alertDialog = dialogBuilder.create();
alertDialog.show();
Update 2:
As you are using View object created by Inflater to update UI components else you can directly use setView(int layourResId)
method of AlertDialog.Builder
class, which is available from API 21 and onwards.