Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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 org.apache.cassandra.schema; import java.util.Iterator; import java.util.function.Predicate; import java.util.stream.Stream; import com.google.common.collect.ImmutableMap; import com.google.common.collect.MapDifference; import com.google.common.collect.Maps; public final class Keyspaces implements Iterable<KeyspaceMetadata> { private final ImmutableMap<String, KeyspaceMetadata> keyspaces; private Keyspaces(Builder builder) { keyspaces = builder.keyspaces.build(); } public static Builder builder() { return new Builder(); } public static Keyspaces none() { return builder().build(); } public static Keyspaces of(KeyspaceMetadata... keyspaces) { return builder().add(keyspaces).build(); } public Iterator<KeyspaceMetadata> iterator() { return keyspaces.values().iterator(); } public Stream<KeyspaceMetadata> stream() { return keyspaces.values().stream(); } public Keyspaces filter(Predicate<KeyspaceMetadata> predicate) { Builder builder = builder(); stream().filter(predicate).forEach(builder::add); return builder.build(); } MapDifference<String, KeyspaceMetadata> diff(Keyspaces other) { return Maps.difference(keyspaces, other.keyspaces); } @Override public boolean equals(Object o) { return this == o || (o instanceof Keyspaces && keyspaces.equals(((Keyspaces) o).keyspaces)); } @Override public int hashCode() { return keyspaces.hashCode(); } @Override public String toString() { return keyspaces.values().toString(); } public static final class Builder { private final ImmutableMap.Builder<String, KeyspaceMetadata> keyspaces = new ImmutableMap.Builder<>(); private Builder() { } public Keyspaces build() { return new Keyspaces(this); } public Builder add(KeyspaceMetadata keyspace) { keyspaces.put(keyspace.name, keyspace); return this; } public Builder add(KeyspaceMetadata... keyspaces) { for (KeyspaceMetadata keyspace : keyspaces) add(keyspace); return this; } public Builder add(Iterable<KeyspaceMetadata> keyspaces) { keyspaces.forEach(this::add); return this; } } }