Java tutorial
/* * Copyright (C) 2013 The Android Open Source Project * * 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. */ package android.media; import android.annotation.IntDef; import android.os.Parcel; import android.os.Parcelable; import android.util.Log; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; /** * A class to encapsulate rating information used as content metadata. * A rating is defined by its rating style (see {@link #RATING_HEART}, * {@link #RATING_THUMB_UP_DOWN}, {@link #RATING_3_STARS}, {@link #RATING_4_STARS}, * {@link #RATING_5_STARS} or {@link #RATING_PERCENTAGE}) and the actual rating value (which may * be defined as "unrated"), both of which are defined when the rating instance is constructed * through one of the factory methods. */ public final class Rating implements Parcelable { private final static String TAG = "Rating"; /** * @hide */ @IntDef({ RATING_NONE, RATING_HEART, RATING_THUMB_UP_DOWN, RATING_3_STARS, RATING_4_STARS, RATING_5_STARS, RATING_PERCENTAGE }) @Retention(RetentionPolicy.SOURCE) public @interface Style { } /** * @hide */ @IntDef({ RATING_3_STARS, RATING_4_STARS, RATING_5_STARS }) @Retention(RetentionPolicy.SOURCE) public @interface StarStyle { } /** * Indicates a rating style is not supported. A Rating will never have this * type, but can be used by other classes to indicate they do not support * Rating. */ public final static int RATING_NONE = 0; /** * A rating style with a single degree of rating, "heart" vs "no heart". Can be used to * indicate the content referred to is a favorite (or not). */ public final static int RATING_HEART = 1; /** * A rating style for "thumb up" vs "thumb down". */ public final static int RATING_THUMB_UP_DOWN = 2; /** * A rating style with 0 to 3 stars. */ public final static int RATING_3_STARS = 3; /** * A rating style with 0 to 4 stars. */ public final static int RATING_4_STARS = 4; /** * A rating style with 0 to 5 stars. */ public final static int RATING_5_STARS = 5; /** * A rating style expressed as a percentage. */ public final static int RATING_PERCENTAGE = 6; private final static float RATING_NOT_RATED = -1.0f; private final int mRatingStyle; private final float mRatingValue; private Rating(@Style int ratingStyle, float rating) { mRatingStyle = ratingStyle; mRatingValue = rating; } @Override public String toString() { return "Rating:style=" + mRatingStyle + " rating=" + (mRatingValue < 0.0f ? "unrated" : String.valueOf(mRatingValue)); } @Override public int describeContents() { return mRatingStyle; } @Override public void writeToParcel(Parcel dest, int flags) { dest.writeInt(mRatingStyle); dest.writeFloat(mRatingValue); } public static final Parcelable.Creator<Rating> CREATOR = new Parcelable.Creator<Rating>() { /** * Rebuilds a Rating previously stored with writeToParcel(). * @param p Parcel object to read the Rating from * @return a new Rating created from the data in the parcel */ @Override public Rating createFromParcel(Parcel p) { return new Rating(p.readInt(), p.readFloat()); } @Override public Rating[] newArray(int size) { return new Rating[size]; } }; /** * Return a Rating instance with no rating. * Create and return a new Rating instance with no rating known for the given * rating style. * @param ratingStyle one of {@link #RATING_HEART}, {@link #RATING_THUMB_UP_DOWN}, * {@link #RATING_3_STARS}, {@link #RATING_4_STARS}, {@link #RATING_5_STARS}, * or {@link #RATING_PERCENTAGE}. * @return null if an invalid rating style is passed, a new Rating instance otherwise. */ public static Rating newUnratedRating(@Style int ratingStyle) { switch (ratingStyle) { case RATING_HEART: case RATING_THUMB_UP_DOWN: case RATING_3_STARS: case RATING_4_STARS: case RATING_5_STARS: case RATING_PERCENTAGE: return new Rating(ratingStyle, RATING_NOT_RATED); default: return null; } } /** * Return a Rating instance with a heart-based rating. * Create and return a new Rating instance with a rating style of {@link #RATING_HEART}, * and a heart-based rating. * @param hasHeart true for a "heart selected" rating, false for "heart unselected". * @return a new Rating instance. */ public static Rating newHeartRating(boolean hasHeart) { return new Rating(RATING_HEART, hasHeart ? 1.0f : 0.0f); } /** * Return a Rating instance with a thumb-based rating. * Create and return a new Rating instance with a {@link #RATING_THUMB_UP_DOWN} * rating style, and a "thumb up" or "thumb down" rating. * @param thumbIsUp true for a "thumb up" rating, false for "thumb down". * @return a new Rating instance. */ public static Rating newThumbRating(boolean thumbIsUp) { return new Rating(RATING_THUMB_UP_DOWN, thumbIsUp ? 1.0f : 0.0f); } /** * Return a Rating instance with a star-based rating. * Create and return a new Rating instance with one of the star-base rating styles * and the given integer or fractional number of stars. Non integer values can for instance * be used to represent an average rating value, which might not be an integer number of stars. * @param starRatingStyle one of {@link #RATING_3_STARS}, {@link #RATING_4_STARS}, * {@link #RATING_5_STARS}. * @param starRating a number ranging from 0.0f to 3.0f, 4.0f or 5.0f according to * the rating style. * @return null if the rating style is invalid, or the rating is out of range, * a new Rating instance otherwise. */ public static Rating newStarRating(@StarStyle int starRatingStyle, float starRating) { float maxRating = -1.0f; switch (starRatingStyle) { case RATING_3_STARS: maxRating = 3.0f; break; case RATING_4_STARS: maxRating = 4.0f; break; case RATING_5_STARS: maxRating = 5.0f; break; default: Log.e(TAG, "Invalid rating style (" + starRatingStyle + ") for a star rating"); return null; } if ((starRating < 0.0f) || (starRating > maxRating)) { Log.e(TAG, "Trying to set out of range star-based rating"); return null; } return new Rating(starRatingStyle, starRating); } /** * Return a Rating instance with a percentage-based rating. * Create and return a new Rating instance with a {@link #RATING_PERCENTAGE} * rating style, and a rating of the given percentage. * @param percent the value of the rating * @return null if the rating is out of range, a new Rating instance otherwise. */ public static Rating newPercentageRating(float percent) { if ((percent < 0.0f) || (percent > 100.0f)) { Log.e(TAG, "Invalid percentage-based rating value"); return null; } else { return new Rating(RATING_PERCENTAGE, percent); } } /** * Return whether there is a rating value available. * @return true if the instance was not created with {@link #newUnratedRating(int)}. */ public boolean isRated() { return mRatingValue >= 0.0f; } /** * Return the rating style. * @return one of {@link #RATING_HEART}, {@link #RATING_THUMB_UP_DOWN}, * {@link #RATING_3_STARS}, {@link #RATING_4_STARS}, {@link #RATING_5_STARS}, * or {@link #RATING_PERCENTAGE}. */ @Style public int getRatingStyle() { return mRatingStyle; } /** * Return whether the rating is "heart selected". * @return true if the rating is "heart selected", false if the rating is "heart unselected", * if the rating style is not {@link #RATING_HEART} or if it is unrated. */ public boolean hasHeart() { if (mRatingStyle != RATING_HEART) { return false; } else { return (mRatingValue == 1.0f); } } /** * Return whether the rating is "thumb up". * @return true if the rating is "thumb up", false if the rating is "thumb down", * if the rating style is not {@link #RATING_THUMB_UP_DOWN} or if it is unrated. */ public boolean isThumbUp() { if (mRatingStyle != RATING_THUMB_UP_DOWN) { return false; } else { return (mRatingValue == 1.0f); } } /** * Return the star-based rating value. * @return a rating value greater or equal to 0.0f, or a negative value if the rating style is * not star-based, or if it is unrated. */ public float getStarRating() { switch (mRatingStyle) { case RATING_3_STARS: case RATING_4_STARS: case RATING_5_STARS: if (isRated()) { return mRatingValue; } default: return -1.0f; } } /** * Return the percentage-based rating value. * @return a rating value greater or equal to 0.0f, or a negative value if the rating style is * not percentage-based, or if it is unrated. */ public float getPercentRating() { if ((mRatingStyle != RATING_PERCENTAGE) || !isRated()) { return -1.0f; } else { return mRatingValue; } } }