Util.java

/*
 * Copyright (C) 2014 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 com.google.android.exoplayer.util;

import com.google.android.exoplayer.upstream.DataSource;

import java.io.IOException;
import java.net.URL;
import java.util.Locale;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ThreadFactory;

/**
 * Miscellaneous utility functions.
 */
public final class Util {

  /**
   * Like {@link android.os.Build.VERSION#SDK_INT}, but in a place where it can be conveniently
   * overridden for local testing.
   */
  public static final int SDK_INT = android.os.Build.VERSION.SDK_INT;

  private Util() {}

  /**
   * Returns true if the URL points to a file on the local device
   *
   * @param url The URL to test
   */
  public static boolean isUrlLocalFile(URL url) {
    return url.getProtocol().equals("file");
  }

  /**
   * Tests two objects for {@link Object#equals(Object)} equality, handling the case where one or
   * both may be null.
   *
   * @param o1 The first object.
   * @param o2 The second object.
   * @return {@code o1 == null ? o2 == null : o1.equals(o2)}.
   */
  public static boolean areEqual(Object o1, Object o2) {
    return o1 == null ? o2 == null : o1.equals(o2);
  }

  /**
   * Instantiates a new single threaded executor whose thread has the specified name.
   *
   * @param threadName The name of the thread.
   * @return The executor.
   */
  public static ExecutorService newSingleThreadExecutor(final String threadName) {
    return Executors.newSingleThreadExecutor(new ThreadFactory() {
      @Override
      public Thread newThread(Runnable r) {
        return new Thread(r, threadName);
      }
    });
  }

  /**
   * Instantiates a new single threaded scheduled executor whose thread has the specified name.
   *
   * @param threadName The name of the thread.
   * @return The executor.
   */
  public static ScheduledExecutorService newSingleThreadScheduledExecutor(final String threadName) {
    return Executors.newSingleThreadScheduledExecutor(new ThreadFactory() {
      @Override
      public Thread newThread(Runnable r) {
        return new Thread(r, threadName);
      }
    });
  }

  /**
   * Closes a {@link DataSource}, suppressing any {@link IOException} that may occur.
   *
   * @param dataSource The {@link DataSource} to close.
   */
  public static void closeQuietly(DataSource dataSource) {
    try {
      dataSource.close();
    } catch (IOException e) {
      // Ignore.
    }
  }

  /**
   * Converts text to lower case using {@link Locale#US}.
   *
   * @param text The text to convert.
   * @return The lower case text, or null if {@code text} is null.
   */
  public static String toLowerInvariant(String text) {
    return text == null ? null : text.toLowerCase(Locale.US);
  }

}