Don't remove public access of averageBitrate field in AudioStream and resolution and isVideoOnly fields in VideoStream but deprecate their use

Getters should be used instead of the fields, like for the others.

Return a new constant (one for the AudioStream class, one for the VideoStream class, but they have the same value (because this method is not implemented in the Stream class)) for streams which don't have an itag instead of 0: ITAG_NOT_AVAILABLE_OR_NOT_APPLICABLE, which is equal to -1 (because an itag id should be not negative).
Also fix some small issues in the Stream class.

Author: AudricV

extractor/src/main/java/org/schabi/newpipe/extractor/stream/AudioStream.java

@@ -32,9 +32,22 @@ public class AudioStream extends Stream {
 
     public static final int UNKNOWN_BITRATE = -1;
 
-    private final int averageBitrate;
+    /**
+     * An integer to represent that the itag id returned is not available (only for YouTube, this
+     * should never happen) or not applicable (for other services than YouTube).
+     *
+     * <p>
+     * An itag should not have a negative value so {@code -1} is used for this constant.
+     * </p>
+     */
+    public static final int ITAG_NOT_AVAILABLE_OR_NOT_APPLICABLE = -1;
+
+    /** @deprecated Use {@link #getAverageBitrate()} instead. */
+    @Deprecated
+    public final int averageBitrate;
+
     // Fields for DASH
-    private int itag;
+    private int itag = ITAG_NOT_AVAILABLE_OR_NOT_APPLICABLE;
     private int bitrate;
     private int initStart;
     private int initEnd;
@@ -168,9 +181,14 @@ public int getAverageBitrate() {
     }
 
     /**
-     * Get the itag of the stream.
+     * Get the itag identifier of the stream.
+     *
+     * <p>
+     * Always equals to {@link #ITAG_NOT_AVAILABLE_OR_NOT_APPLICABLE} for other streams than the
+     * ones of the YouTube service.
+     * </p>
      *
-     * @return the number of the {@link ItagItem} passed in the constructor of the stream.
+     * @return the number of the {@link ItagItem} passed in the constructor of the audio stream.
      */
     public int getItag() {
         return itag;

extractor/src/main/java/org/schabi/newpipe/extractor/stream/Stream.java

@@ -17,17 +17,17 @@
 public abstract class Stream implements Serializable {
     private static final long serialVersionUID = -59591092068744672L;
 
+    public static final int FORMAT_ID_UNKNOWN = -1;
+
     private final String id;
     @Nullable private final MediaFormat mediaFormat;
     private final String content;
     private final boolean isUrl;
     private final DeliveryMethod deliveryMethod;
     @Nullable private final String baseUrl;
 
-    public static final int FORMAT_ID_UNKNOWN = -1;
-
     /**
-     * Instantiates a new stream object.
+     * Instantiates a new {@code Stream} object.
      *
      * @param id             the ID which uniquely identifies the file, e.g. for YouTube this would
      *                       be the itag
@@ -54,7 +54,7 @@ protected Stream(final String id,
     }
 
     /**
-     * Check if the list already contains one stream with equals stats.
+     * Checks if the list already contains one stream with equals stats.
      *
      * @param stream the stream which will be compared to the streams in the stream list
      * @param streamList the list of {@link Stream Streams} which will be compared
@@ -81,22 +81,26 @@ public static boolean containSimilarStream(final Stream stream,
      * If the {@link MediaFormat media format} of the stream is unknown, the streams are compared
      * by only using the {@link DeliveryMethod delivery method} and their id.
      * </p>
+     *
      * <p>
      * Note: This method always returns always false if the stream passed is null.
      * </p>
+     *
      * @param cmp the stream object to be compared to this stream object
      * @return whether the stream have the same stats or not, based on the criteria above
      */
     public boolean equalStats(final Stream cmp) {
         if (cmp == null) {
             return false;
         }
+
         Boolean haveSameMediaFormatId = null;
         if (mediaFormat != null && cmp.mediaFormat != null) {
             haveSameMediaFormatId = mediaFormat.id == cmp.mediaFormat.id;
         }
         final boolean areUsingSameDeliveryMethodAndAreUrlStreams =
                 deliveryMethod == cmp.deliveryMethod && isUrl == cmp.isUrl;
+
         return haveSameMediaFormatId != null
                 ? haveSameMediaFormatId && areUsingSameDeliveryMethodAndAreUrlStreams
                 : areUsingSameDeliveryMethodAndAreUrlStreams;
@@ -113,7 +117,7 @@ public boolean equals(final Stream cmp) {
     }
 
     /**
-     * Gets the ID for this stream, e.g. itag for YouTube.
+     * Gets the identifier of this stream, e.g. the itag for YouTube.
      *
      * @return the id
      */
@@ -122,10 +126,10 @@ public String getId() {
     }
 
     /**
-     * Gets the URL.
+     * Gets the URL of this stream if the content is a URL, or {@code null} if that's the not case.
      *
      * @return the URL if the content is a URL, {@code null} otherwise
-     * @deprecated Use {@link #getContent()} instead
+     * @deprecated Use {@link #getContent()} instead.
      */
     @Deprecated
     @Nullable
@@ -186,6 +190,7 @@ public DeliveryMethod getDeliveryMethod() {
 
     /**
      * Gets the base URL of a stream.
+     *
      * <p>
      * If the stream is not a DASH stream or an HLS stream, this value will always be null.
      * It may be also null for these streams too.
@@ -200,6 +205,7 @@ public String getBaseUrl() {
 
     /**
      * Gets the {@link ItagItem} of a stream.
+     *
      * <p>
      * If the stream is not a YouTube stream, this value will always be null.
      * </p>

extractor/src/main/java/org/schabi/newpipe/extractor/stream/VideoStream.java

@@ -32,10 +32,26 @@ public class VideoStream extends Stream {
 
     public static final String RESOLUTION_UNKNOWN = "";
 
-    private final String resolution;
-    private final boolean isVideoOnly;
+    /**
+     * An integer to represent that the itag id returned is not available (only for YouTube, this
+     * should never happen) or not applicable (for other services than YouTube).
+     *
+     * <p>
+     * An itag should not have a negative value so {@code -1} is used for this constant.
+     * </p>
+     */
+    public static final int ITAG_NOT_AVAILABLE_OR_NOT_APPLICABLE = -1;
+
+    /** @deprecated Use {@link #getResolution()} instead. */
+    @Deprecated
+    public final String resolution;
+
+    /** @deprecated Use {@link #isVideoOnly()} instead. */
+    @Deprecated
+    public final boolean isVideoOnly;
+
     // Fields for DASH
-    private int itag;
+    private int itag = ITAG_NOT_AVAILABLE_OR_NOT_APPLICABLE;
     private int bitrate;
     private int initStart;
     private int initEnd;
@@ -141,6 +157,7 @@ public VideoStream(final String id,
 
     /**
      * Create a new video stream.
+     *
      * <p>
      * The media format and the resolution will be set by using respectively
      * {@link ItagItem#getMediaFormat()} and {@link ItagItem#resolutionString}.
@@ -183,6 +200,7 @@ public boolean equalStats(final Stream cmp) {
 
     /**
      * Get the video resolution.
+     *
      * <p>
      * It can be unknown for some streams, like for HLS master playlists. In this case,
      * {@link #RESOLUTION_UNKNOWN} is returned by this method.
@@ -195,7 +213,8 @@ public String getResolution() {
     }
 
     /**
-     * Return if the stream is video-only.
+     * Return whether the stream is video-only.
+     *
      * <p>
      * Video-only streams have no audio.
      * </p>
@@ -207,9 +226,14 @@ public boolean isVideoOnly() {
     }
 
     /**
-     * Get the itag of the stream.
+     * Get the itag identifier of the stream.
+     *
+     * <p>
+     * Always equals to {@link #ITAG_NOT_AVAILABLE_OR_NOT_APPLICABLE} for other streams than the
+     * ones of the YouTube service.
+     * </p>
      *
-     * @return the number of the {@link ItagItem} passed in the constructor of the stream.
+     * @return the number of the {@link ItagItem} passed in the constructor of the video stream.
      */
     public int getItag() {
         return itag;