Simple utils for Realm.io database

RealmUtil.java

package in.ccrowd.base.database;

import com.annimon.stream.Collectors;
import com.annimon.stream.Stream;

import io.realm.Realm;
import io.realm.RealmModel;
import io.realm.RealmObject;
import rx.functions.Func0;

public class RealmUtil {

  public static void handleTransaction(final RunnableWithRealm toExecute) {
    final Realm realm = Realm.getDefaultInstance();
    boolean alreadyInTransaction = realm.isInTransaction();
    if (!alreadyInTransaction) {
      realm.beginTransaction();
    }
    toExecute.execute(realm);
    if (!alreadyInTransaction) {
      realm.commitTransaction();
    }
  }

  public static void handleTransaction(final Runnable toExecute) {
    handleTransaction(realm -> toExecute.run());
  }

  public static <T> T handleTransactionForResult(final Returnable<T> toExecute) {
    return handleTransactionForResult(realm -> toExecute.getValue());
  }


  public static <T> T handleTransactionForResult(final ReturnableWithRealm<T> toExecute) {
    final Realm realm = Realm.getDefaultInstance();
    boolean alreadyInTransaction = realm.isInTransaction();
    if (!alreadyInTransaction) {
      realm.beginTransaction();
    }
    T value = toExecute.getValue(realm);
    if (!alreadyInTransaction) {
      realm.commitTransaction();
    }
    return value;
  }

  public static <T extends WithId> T newInstance(final Class<T> clazz, final Func0<T> generator) {
    return newInstance(() -> {
      final T object = generator.call();
      object.setId(PrimaryKeyFactory.getNextId(clazz));
      return object;
    });
  }

  public static <T extends WithId> T newInstance(final Func0<T> generator) {
    return RealmUtil.handleTransactionForResult(() -> {
      final T object = generator.call();
      return Realm.getDefaultInstance()
                  .copyToRealmOrUpdate(object);
    });
  }

  public static <T extends RealmObject> T getById(final Class<T> clazz, final long id) {
    return Realm.getDefaultInstance()
                .where(clazz)
                .equalTo(Column.ID, id)
                .findFirst();
  }

  public static String getField(final String... fields) {
    return Stream.of(fields)
                 .collect(Collectors.joining("."));
  }

  public interface RunnableWithRealm {
    void execute(Realm realm);
  }

  public interface Returnable<T> {
    T getValue();
  }

  public interface ReturnableWithRealm<T> {
    T getValue(Realm realm);
  }

  public interface WithId extends RealmModel {

    int getId();

    void setId(int id);

  }

}