com.twitter.util.javainterop.Scala Maven / Gradle / Ivy

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package com.twitter.util.javainterop;

import scala.Option;
import scala.Tuple2;

import scala.collection.JavaConverters;

/**
 * A collection of conversions from Java collections to their immutable
 * Scala variants.
 *
 * See scala.collection.JavaConverters if you do not need immutable
 * collections.
 */
public final class Scala {

  private Scala() { throw new IllegalStateException(); }

  /**
   * Converts a {@link java.util.List} to an immutable Scala Seq.
   *
   * See scala.collection.JavaConverters.asScalaBuffer if you do
   * not need the returned Seq to be immutable.
   *
   * @return an empty Seq if the input is null.
   */
  @SuppressWarnings("unchecked")
  public static  scala.collection.immutable.Seq asImmutableSeq(
      java.util.List jList
  ) {
    if (jList == null) {
      return scala.collection.immutable.Seq$.MODULE$.empty();
    } else {
      return JavaConverters.asScalaBuffer(jList).toList();
    }
  }

  /**
   * Converts a {@link java.util.Set} to an immutable Scala Set.
   *
   * See scala.collection.JavaConverters.asScalaSet if you do
   * not need the returned Set to be immutable.
   *
   * @return an empty Set if the input is null.
   */
  @SuppressWarnings("unchecked")
  public static  scala.collection.immutable.Set asImmutableSet(
      java.util.Set jSet
  ) {
    if (jSet == null) {
      return scala.collection.immutable.Set$.MODULE$.empty();
    } else {
      return JavaConverters.asScalaSet(jSet).toSet();
    }
  }

  /**
   * Converts a {@link java.util.Map} to an immutable Scala Map.
   *
   * See scala.collection.JavaConverters.asScalaMap if you do
   * not need the returned Map to be immutable.
   *
   * @return an empty Map if the input is null.
   */
  public static  scala.collection.immutable.Map asImmutableMap(
      java.util.Map jMap
  ) {
    scala.collection.immutable.Map sMap = scala.collection.immutable.Map$.MODULE$.empty();
    if (jMap != null) {
      for (java.util.Map.Entry entry : jMap.entrySet()) {
        sMap = sMap.$plus(new Tuple2(entry.getKey(), entry.getValue()));
      }
    }
    return sMap;
  }

  /**
   * Converts a {@link java.util.Optional} to a Scala Option.
   */
  public static  Option asOption(
      java.util.Optional optional
  ) {
    if (optional.isPresent()) return Option.apply(optional.get());
    else return Option.empty();
  }

}