Improve sniffer error reporting.

- Make UnrecognizedInputFormatException public so the app can more easily handle
  it when it is propagated to onPlayerError.
- Format the description using the simple class names for the extractors.
- Don't retry loading after it's thrown, but just throw immediately.

library/src/main/java/com/google/android/exoplayer/extractor/ExtractorSampleSource.java

@@ -32,6 +32,7 @@ import com.google.android.exoplayer.upstream.DefaultAllocator;
 import com.google.android.exoplayer.upstream.Loader;
 import com.google.android.exoplayer.upstream.Loader.Loadable;
 import com.google.android.exoplayer.util.Assertions;
+import com.google.android.exoplayer.util.Util;
 
 import android.net.Uri;
 import android.os.SystemClock;
@@ -40,7 +41,6 @@ import android.util.SparseArray;
 import java.io.EOFException;
 import java.io.IOException;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.List;
 
 /**
@@ -70,6 +70,18 @@ import java.util.List;
 public class ExtractorSampleSource implements SampleSource, SampleSourceReader, ExtractorOutput,
     Loader.Callback {
 
+  /**
+   * Thrown if the input format could not recognized.
+   */
+  public static final class UnrecognizedInputFormatException extends ParserException {
+
+    public UnrecognizedInputFormatException(Extractor[] extractors) {
+      super("None of the available extractors ("
+          + Util.getCommaDelimitedSimpleClassNames(extractors) + ") could read the stream.");
+    }
+
+  }
+
   /**
    * The default minimum number of times to retry loading prior to failing for on-demand streams.
    */
@@ -401,6 +413,9 @@ public class ExtractorSampleSource implements SampleSource, SampleSourceReader,
     if (currentLoadableException == null) {
       return;
     }
+    if (isCurrentLoadableExceptionFatal()) {
+      throw currentLoadableException;
+    }
     int minLoadableRetryCountForMedia;
     if (minLoadableRetryCount != MIN_RETRY_COUNT_DEFAULT_FOR_MEDIA) {
       minLoadableRetryCountForMedia = minLoadableRetryCount;
@@ -545,6 +560,9 @@ public class ExtractorSampleSource implements SampleSource, SampleSourceReader,
     }
 
     if (currentLoadableException != null) {
+      if (isCurrentLoadableExceptionFatal()) {
+        return;
+      }
       Assertions.checkState(loadable != null);
       long elapsedMillis = SystemClock.elapsedRealtime() - currentLoadableExceptionTimestamp;
       if (elapsedMillis >= getRetryDelayMillis(currentLoadableExceptionCount)) {
@@ -642,6 +660,10 @@ public class ExtractorSampleSource implements SampleSource, SampleSourceReader,
     return pendingResetPositionUs != NO_RESET_PENDING;
   }
 
+  private boolean isCurrentLoadableExceptionFatal() {
+    return currentLoadableException instanceof UnrecognizedInputFormatException;
+  }
+
   private long getRetryDelayMillis(long errorCount) {
     return Math.min((errorCount - 1) * 1000, 5000);
   }
@@ -791,15 +813,4 @@ public class ExtractorSampleSource implements SampleSource, SampleSourceReader,
 
   }
 
-  /**
-   * Thrown if the input format could not recognized by {@link Extractor#sniff(ExtractorInput)}.
-   */
-  private static final class UnrecognizedInputFormatException extends ParserException {
-
-    public UnrecognizedInputFormatException(Extractor[] extractors) {
-      super("None of the extractors " + Arrays.toString(extractors) + " could read the stream.");
-    }
-
-  }
-
 }

library/src/main/java/com/google/android/exoplayer/util/Util.java

@@ -577,11 +577,28 @@ public final class Util {
    * @return A string containing the hex representation of the data provided.
    */
   public static String getHexStringFromBytes(byte[] data, int beginIndex, int endIndex) {
-    StringBuffer dataStringBuffer = new StringBuffer(endIndex - beginIndex);
+    StringBuilder dataStringBuilder = new StringBuilder(endIndex - beginIndex);
     for (int i = beginIndex; i < endIndex; i++) {
-      dataStringBuffer.append(String.format(Locale.US, "%02X", data[i]));
+      dataStringBuilder.append(String.format(Locale.US, "%02X", data[i]));
     }
-    return dataStringBuffer.toString();
+    return dataStringBuilder.toString();
+  }
+
+  /**
+   * Returns a string with comma delimited simple names of each object's class.
+   *
+   * @param objects The objects whose simple class names should be comma delimited and returned.
+   * @return A string with comma delimited simple names of each object's class.
+   */
+  public static <T> String getCommaDelimitedSimpleClassNames(T[] objects) {
+    StringBuilder stringBuilder = new StringBuilder();
+    for (int i = 0; i < objects.length; i++) {
+      stringBuilder.append(objects[i].getClass().getSimpleName());
+      if (i < objects.length - 1) {
+        stringBuilder.append(", ");
+      }
+    }
+    return stringBuilder.toString();
   }
 
   /**