How to make Material Exposed Drop Down List required field in Java

I am using Material Exposed Drop Down List to add information to my Firebase database, and I need to make the drop down lists a required field before the information saves. Currently the information will save but saves the field as null, which makes my add crash on a different activity.

The code I am currently using at the moment treats the drop down like an EditText, but this isn't working.

I am defining the drop down menu and capturing the user input (if made) like this:

 //CPD TYPE DROPDOWN MENU
    cpdTypeLayout = findViewById(R.id.cpdTypeLayout);
    cpdType = findViewById(R.id.cpdType);

    final String[] type = new String[]{
            "Formal Education Completed", "Other Completed", "Professional Activities", "Self-Directed Learning", "Work-Based Learning"
    };

    final ArrayAdapter<String> adapterType = new ArrayAdapter<>(
            AddActivity.this,
            R.layout.dropdown_item,
            type
    );

    cpdType.setAdapter(adapterType);

    //TO CAPTURE USER SELECTION FROM DROP DOWN LIST
    ((AutoCompleteTextView)cpdTypeLayout.getEditText()).setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            adapterType.getItem(position);
            selectedType = ((AutoCompleteTextView)cpdTypeLayout.getEditText()).getText().toString();
            Log.d("TAG", "selected type is: " + selectedType);
        }
    });

I am then using this code to check if anything is empty before adding to Firebase, but the checks do not stop the save being made.

if (selectedType.isEmpty() || selectedHours.isEmpty() || selectedMins.isEmpty()) {
                            Toast.makeText(AddActivity.this, "Can not save activity with empty fields", Toast.LENGTH_SHORT).show();
                            return;
                        }

I have also tried using selectedType == null but this doesn't work either.

I'm not sure if I need to add something to my XML file or in my Java file to prevent this from happening

I managed to solve this by myself by adding the following to my save button click:

fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (selectedType.trim().length() != 0 && selectedHours.trim().length() != 0 && selectedMins.trim().length() != 0){
                    uploadToFirebase();
                } else {
                    if (selectedType.trim().length() == 0) {
                        cpdTypeLayout.setError("Please select Activity Type");
                    }
                    if (selectedHours.trim().length() == 0) {
                        cpdHoursLayout.setError("Please select Hours");
                    }
                    if (selectedMins.trim().length() == 0){
                        cpdMinsLayout.setError("Please select Minutes");
                    }
                }
            }
        });