1 /* 2 * Copyright (c) 2016, The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 package com.android.car.radio; 17 18 import android.content.AsyncTaskLoader; 19 import android.content.Context; 20 import android.support.annotation.NonNull; 21 import com.android.car.radio.service.RadioStation; 22 23 import java.util.Collections; 24 import java.util.List; 25 26 /** 27 * An {@link AsyncTaskLoader} that will load all the pre-scanned radio stations for a given band. 28 */ 29 public class PreScannedChannelLoader extends AsyncTaskLoader<List<RadioStation>> { 30 private final static int INVALID_RADIO_BAND = -1; 31 32 private final RadioStorage mRadioStorage; 33 private int mCurrentRadioBand = INVALID_RADIO_BAND; 34 PreScannedChannelLoader(Context context)35 public PreScannedChannelLoader(Context context) { 36 super(context); 37 mRadioStorage = RadioStorage.getInstance(context); 38 } 39 40 /** 41 * Sets the radio band that this loader should load the pre-scanned stations for. 42 * 43 * @param radioBand One of the band values in {@link android.hardware.radio.RadioManager}. For 44 * example, {@link android.hardware.radio.RadioManager#BAND_FM}. 45 */ setCurrentRadioBand(int radioBand)46 public void setCurrentRadioBand(int radioBand) { 47 mCurrentRadioBand = radioBand; 48 } 49 50 /** 51 * Returns a list of {@link RadioStation}s representing the pre-scanned channels for the band 52 * specified by {@link #INVALID_RADIO_BAND}. If no stations exist for the given band, then an 53 * empty list is returned. 54 */ 55 @NonNull 56 @Override loadInBackground()57 public List<RadioStation> loadInBackground() { 58 if (mCurrentRadioBand == INVALID_RADIO_BAND) { 59 return Collections.emptyList(); 60 } 61 62 return mRadioStorage.getPreScannedStationsForBand(mCurrentRadioBand); 63 } 64 } 65