Java tutorial
/*** Copyright (c) 2008-2015 CommonsWare, LLC Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0. Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. Covered in detail in the book _The Busy Coder's Guide to Android Development_ https://commonsware.com/Android */ package com.commonsware.android.contacts.spinners; import android.Manifest; import android.database.Cursor; import android.net.Uri; import android.os.Bundle; import android.provider.ContactsContract; import android.support.annotation.NonNull; import android.support.v4.app.LoaderManager; import android.support.v4.content.CursorLoader; import android.support.v4.content.Loader; import android.support.v7.widget.DividerItemDecoration; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.AdapterView; import android.widget.ArrayAdapter; import android.widget.Spinner; import android.widget.TextView; import android.widget.Toast; public class ContactSpinners extends AbstractPermissionActivity implements LoaderManager.LoaderCallbacks<Cursor>, AdapterView.OnItemSelectedListener { private static final String[] PERMS = { Manifest.permission.READ_CONTACTS }; private static final int LOADER_NAMES = 0; private static final int LOADER_NAMES_NUMBERS = 1; private static final String[] PROJECTION_NAMES = new String[] { ContactsContract.Contacts._ID, ContactsContract.Contacts.DISPLAY_NAME, }; private static final String[] PROJECTION_NUMBERS = new String[] { ContactsContract.Contacts._ID, ContactsContract.Contacts.DISPLAY_NAME, ContactsContract.CommonDataKinds.Phone.NUMBER }; private static final String[] PROJECTION_EMAILS = new String[] { ContactsContract.Contacts._ID, ContactsContract.Contacts.DISPLAY_NAME, ContactsContract.CommonDataKinds.Email.DATA }; private static final String[] COLUMNS_NAMES = new String[] { ContactsContract.Contacts.DISPLAY_NAME }; private static final String[] COLUMNS_NUMBERS = new String[] { ContactsContract.Contacts.DISPLAY_NAME, ContactsContract.CommonDataKinds.Phone.NUMBER }; private static final String[] COLUMNS_EMAILS = new String[] { ContactsContract.Contacts.DISPLAY_NAME, ContactsContract.CommonDataKinds.Email.DATA }; private RVCursorAdapter adapter; @Override protected String[] getDesiredPermissions() { return (PERMS); } @Override protected void onPermissionDenied() { Toast.makeText(this, R.string.msg_no_perm, Toast.LENGTH_LONG).show(); finish(); } @Override public void onReady() { setContentView(R.layout.main); Spinner spin = findViewById(R.id.spinner); spin.setOnItemSelectedListener(this); ArrayAdapter<String> aa = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, getResources().getStringArray(R.array.options)); aa.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); spin.setAdapter(aa); RecyclerView rv = findViewById(android.R.id.list); rv.setLayoutManager(new LinearLayoutManager(this)); rv.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL)); adapter = new RVCursorAdapter(getLayoutInflater()); rv.setAdapter(adapter); } @Override public Loader<Cursor> onCreateLoader(int loaderId, Bundle args) { String[] projection; Uri uri; switch (loaderId) { case LOADER_NAMES: projection = PROJECTION_NAMES; uri = ContactsContract.Contacts.CONTENT_URI; break; case LOADER_NAMES_NUMBERS: projection = PROJECTION_NUMBERS; uri = ContactsContract.CommonDataKinds.Phone.CONTENT_URI; break; default: projection = PROJECTION_EMAILS; uri = ContactsContract.CommonDataKinds.Email.CONTENT_URI; break; } return new CursorLoader(this, uri, projection, null, null, ContactsContract.Contacts.DISPLAY_NAME); } @Override public void onLoadFinished(Loader<Cursor> loader, Cursor c) { String[] columns; switch (loader.getId()) { case LOADER_NAMES: columns = COLUMNS_NAMES; break; case LOADER_NAMES_NUMBERS: columns = COLUMNS_NUMBERS; break; default: columns = COLUMNS_EMAILS; break; } adapter.changeCursor(c, columns); } @Override public void onLoaderReset(Loader<Cursor> loader) { adapter.clearCursor(); } @Override public void onItemSelected(AdapterView<?> parent, View v, int position, long id) { getSupportLoaderManager().initLoader(position, null, this); } @Override public void onNothingSelected(AdapterView<?> parent) { // ignore } private static class RVCursorAdapter extends RecyclerView.Adapter<RowHolder> { private Cursor cursor; private final LayoutInflater inflater; private String[] columns; private RVCursorAdapter(LayoutInflater inflater) { this.inflater = inflater; } @NonNull @Override public RowHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) { View row = inflater.inflate(android.R.layout.simple_list_item_2, parent, false); return new RowHolder(row); } @Override public void onBindViewHolder(@NonNull RowHolder holder, int position) { cursor.moveToPosition(position); holder.bind(cursor, columns); } @Override public int getItemCount() { return cursor == null ? 0 : cursor.getCount(); } private void changeCursor(Cursor cursor, String[] columns) { if (this.cursor != null) { this.cursor.close(); } this.cursor = cursor; this.columns = columns; notifyDataSetChanged(); } private void clearCursor() { cursor = null; notifyDataSetChanged(); } } private static class RowHolder extends RecyclerView.ViewHolder { private final TextView text1; private final TextView text2; RowHolder(View itemView) { super(itemView); text1 = itemView.findViewById(android.R.id.text1); text2 = itemView.findViewById(android.R.id.text2); } public void bind(Cursor cursor, String[] columns) { int index = cursor.getColumnIndex(columns[0]); text1.setText(cursor.getString(index)); if (columns.length == 2) { index = cursor.getColumnIndex(columns[1]); text2.setText(cursor.getString(index)); } } } }