Java tutorial
/* Copyright (c) 2013-2014 Boundless and others. * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Distribution License v1.0 * which accompanies this distribution, and is available at * https://www.eclipse.org/org/documents/edl-v10.html * * Contributors: * Victor Olaya (Boundless) - initial implementation */ package org.locationtech.geogig.api.plumbing; import org.eclipse.jdt.annotation.Nullable; import org.locationtech.geogig.api.AbstractGeoGigOp; import org.locationtech.geogig.api.ObjectId; import org.locationtech.geogig.api.Ref; import com.google.common.base.Optional; import com.google.common.base.Preconditions; import com.google.common.base.Predicate; import com.google.common.collect.ImmutableSet; /** * Given an id, returns the ref that points to that id, if it exists * */ public class ResolveBranchId extends AbstractGeoGigOp<Optional<Ref>> { private ObjectId id; public ResolveBranchId setObjectId(ObjectId id) { this.id = id; return this; } @Override protected Optional<Ref> _call() { Preconditions.checkState(id != null, "id has not been set."); Predicate<Ref> filter = new Predicate<Ref>() { @Override public boolean apply(@Nullable Ref ref) { return ref.getObjectId().equals(id); } }; ImmutableSet<Ref> refs = command(ForEachRef.class).setFilter(filter).call(); if (refs.isEmpty()) { return Optional.absent(); } else { return Optional.of(refs.iterator().next()); } } }