Adding Spinner selected value to Listview but app crashes

Question

I'm trying to build a fitness tracker app. When I run the app and leave the EditText blank and hit the save button, it prompts the AlertDialog okay. But when I enter an input (number or letter), the app crashes.

Here's my code, what I'm doing wrong?

private static final String ACTIVITIES = "activities";
        private Spinner spinner1;
        private EditText ETinfo;
        private SharedPreferences savedActivities;
        private ArrayList<String> details;//to save ETinfo from user
        private ArrayAdapter<String> adapter;
        private ArrayList<String> items;//dropdown list of spinner
        private ListView listview1;
        private ArrayList<String> list = new ArrayList<String>();
    spinner1.setOnItemSelectedListener(new OnItemSelectedListener(){

            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                // TODO Auto-generated method stub
                String label = parent.getItemAtPosition(position).toString();
                // Showing selected spinner item
            Toast.makeText(parent.getContext(), "You selected: " + label,Toast.LENGTH_LONG).show();
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {
                // create a new AlertDialog Builder
                AlertDialog.Builder builder = new AlertDialog.Builder(AKMainActivity.this);

                // set dialog's message to display
                builder.setMessage(R.string.empty_message);

                // provide an OK button that simply dismisses the dialog
                builder.setPositiveButton(R.string.OK, null);

                // create AlertDialog from the AlertDialog.Builder
                AlertDialog errorDialog = builder.create();
                errorDialog.show(); // display the modal dialog

            }

        });
        }

            public OnClickListener saveButtonListener = new OnClickListener(){


                @Override
                public void onClick(View v) {
                    if (ETinfo.getText().length() > 0){
                    addDetailedActivity(spinner1.getSelectedItem().toString(), ETinfo.getText().toString());
                    ETinfo.setText("");
                    spinner1.setSelection(0);


                    // code to remove the keyboard from screen
                    ((InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE))
                        .hideSoftInputFromWindow(ETinfo.getWindowToken(), 0);
                    }
                    else{
                        // create a new AlertDialog Builder
                        AlertDialog.Builder builder = new AlertDialog.Builder(AKMainActivity.this);

                        // set dialog's message to display
                        builder.setMessage(R.string.empty_message);

                        // provide an OK button that simply dismisses the dialog
                        builder.setPositiveButton(R.string.OK, null);

                        // create AlertDialog from the AlertDialog.Builder
                        AlertDialog errorDialog = builder.create();
                        errorDialog.show(); // display the modal dialog
                    } };

            private void addDetailedActivity(String userChoice, String info) {
                     // store current activity and info
                    preferencesEditor.putString(userChoice, spinner1.getSelectedItem().toString());
                    preferencesEditor.putString(info, ETinfo.getText().toString());
                    preferencesEditor.apply();
                    //to notify adapter after that changes in data
                    adapter.notifyDataSetChanged();

                    if (!details.contains(info)) {
                        details.add(info); // add new activity info
                        Collections.sort(details, String.CASE_INSENSITIVE_ORDER);
                        adapter.notifyDataSetChanged(); // rebind info to ListView

                    }

                    }
    ;
            };}