Question

I’m new to Java/android so a lot of these terms are foreign but am willing to learn. I’m not gonna go into detail on the app as I dont think it’s relevant. My issue as it stands, I’ve used tutorials and pieces of code from a blog and have gotten my code to work. Trying to clean up and organize my code I get a nullpoiner exception when I move one line (creating my autocompletetextview). Below is the code I’ve used. My 1 line of code that’s giving me an issue is

AutoCompleteTextView companyAutoComplete = (AutoCompleteTextView) addAddressDialog.findViewById(R.id.add_record_dialog_autocomplete);

When I move it to right under the start of my function it errors out but when left in place it works like a charm. I’d like to understand why this is.

public void addAddress() {
    final Dialog addAddressDialog = new Dialog(this);
    final int[] to = new int[] { android.R.id.text1 };
    final String[] from = new String[] { "CompanyName" };

    // Create a SimpleCursorAdapter for the CompanyName field.
    SimpleCursorAdapter adapter =  new SimpleCursorAdapter(this, android.R.layout. select_dialog_item, null, from, to);

    addAddressDialog.setContentView(R.layout.add_record_dialog);
    addAddressDialog.setTitle(getString(R.string.add_record_dialog_address_title));
    addAddressDialog.setCancelable(true);

    final EditText text1 = (EditText) addAddressDialog.findViewById(R.id.add_record_dialog_edittext);
    text1.setHint(getString(R.string.add_record_dialog_company_hint));

    Button buttonOK1 = (Button) addAddressDialog.findViewById(R.id.add_record_dialog_ok);
    buttonOK1.setText(getString(R.string.add_record_dialog_ok_button));

    Button buttonCancel1 = (Button) addAddressDialog.findViewById(R.id.add_record_dialog_cancel);
    buttonCancel1.setText(getString(R.string.add_record_dialog_cancel_button));

    buttonOK1.setOnClickListener(new OnClickListener(){
        public void onClick(View v) {
            Bundle addressBundle = new Bundle();
            addressBundle.putString("CompanyName", text1.getText().toString());

            Intent intent = new Intent(MenuActivity.this, AddAddressActivity.class);
            intent.putExtras(addressBundle);
            startActivity(intent);

            addAddressDialog.dismiss();
        }   
    });

    buttonCancel1.setOnClickListener(new OnClickListener(){
        public void onClick(View v) {
            Toast.makeText(getBaseContext(), "Cancel button clicked", Toast.LENGTH_SHORT).show();
            addAddressDialog.dismiss();
        }   
    });
    AutoCompleteTextView companyAutoComplete = (AutoCompleteTextView) addAddressDialog.findViewById(R.id.add_record_dialog_autocomplete);

    companyAutoComplete.setAdapter(adapter);

    // Set an OnItemClickListener, to update dependent fields when
    // a choice is made in the AutoCompleteTextView.
    companyAutoComplete.setOnItemClickListener(new OnItemClickListener() {
        public void onItemClick(AdapterView<?> listView, View view,
                    int position, long id) {
            // Get the cursor, positioned to the corresponding row in the
            // result set
            Cursor cursor = (Cursor) listView.getItemAtPosition(position);

            // Get the CompanyID from this row in the database.
            String companyID = cursor.getString(cursor.getColumnIndexOrThrow("_id"));

            // test to make sure CompanyID returned
            Toast.makeText(getBaseContext(), companyID, Toast.LENGTH_SHORT).show();
        }
    });

    // Set the CursorToStringConverter, to provide the labels for the
    // choices to be displayed in the AutoCompleteTextView.
    adapter.setCursorToStringConverter(new CursorToStringConverter() {
        public String convertToString(android.database.Cursor cursor) {
            // Get the label for this row out of the "CompanyName" column
            final int columnIndex = cursor.getColumnIndexOrThrow("CompanyName");
            final String str = cursor.getString(columnIndex);
            return str;
        }
    });

    // Set the FilterQueryProvider, to run queries for choices
    // that match the specified input.
    adapter.setFilterQueryProvider(new FilterQueryProvider() {
        public Cursor runQuery(CharSequence constraint) {
            Cursor cursorReturn = dbAdapter.getCompanies(constraint != null ? constraint.toString() : null);

            startManagingCursor(cursorReturn);
            return cursorReturn;
        }
        });

    addAddressDialog.show();
}

Answer 1

This happens because you call setContentView later.

setContentView sets up the layout for the addAddressDialog dialog. If you don’t call setContentView, it has no layout items, therefore addAddressDialog.findViewById(...); will be null, and, obviously you cannot cast that to anything, nor can you call setHint on it.

It shouldn’t matter where this line of code is in your method, as long as your line with setContentView is called before it.