Java tutorial
/* * Copyright (C) 2013 The Guava Authors * * 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.common.collect; import com.google.common.annotations.GwtCompatible; import com.google.j2objc.annotations.WeakOuter; import java.util.AbstractCollection; import java.util.AbstractSet; import java.util.Collection; import java.util.Iterator; import java.util.Map; import java.util.Set; import javax.annotation.Nullable; /** * Skeletal, implementation-agnostic implementation of the {@link Table} interface. * * @author Louis Wasserman */ @GwtCompatible abstract class AbstractTable<R, C, V> implements Table<R, C, V> { @Override public boolean containsRow(@Nullable Object rowKey) { return Maps.safeContainsKey(rowMap(), rowKey); } @Override public boolean containsColumn(@Nullable Object columnKey) { return Maps.safeContainsKey(columnMap(), columnKey); } @Override public Set<R> rowKeySet() { return rowMap().keySet(); } @Override public Set<C> columnKeySet() { return columnMap().keySet(); } @Override public boolean containsValue(@Nullable Object value) { for (Map<C, V> row : rowMap().values()) { if (row.containsValue(value)) { return true; } } return false; } @Override public boolean contains(@Nullable Object rowKey, @Nullable Object columnKey) { Map<C, V> row = Maps.safeGet(rowMap(), rowKey); return row != null && Maps.safeContainsKey(row, columnKey); } @Override public V get(@Nullable Object rowKey, @Nullable Object columnKey) { Map<C, V> row = Maps.safeGet(rowMap(), rowKey); return (row == null) ? null : Maps.safeGet(row, columnKey); } @Override public boolean isEmpty() { return size() == 0; } @Override public void clear() { Iterators.clear(cellSet().iterator()); } @Override public V remove(@Nullable Object rowKey, @Nullable Object columnKey) { Map<C, V> row = Maps.safeGet(rowMap(), rowKey); return (row == null) ? null : Maps.safeRemove(row, columnKey); } @Override public V put(R rowKey, C columnKey, V value) { return row(rowKey).put(columnKey, value); } @Override public void putAll(Table<? extends R, ? extends C, ? extends V> table) { for (Table.Cell<? extends R, ? extends C, ? extends V> cell : table.cellSet()) { put(cell.getRowKey(), cell.getColumnKey(), cell.getValue()); } } private transient Set<Cell<R, C, V>> cellSet; @Override public Set<Cell<R, C, V>> cellSet() { Set<Cell<R, C, V>> result = cellSet; return (result == null) ? cellSet = createCellSet() : result; } Set<Cell<R, C, V>> createCellSet() { return new CellSet(); } abstract Iterator<Table.Cell<R, C, V>> cellIterator(); @WeakOuter class CellSet extends AbstractSet<Cell<R, C, V>> { @Override public boolean contains(Object o) { if (o instanceof Cell) { Cell<?, ?, ?> cell = (Cell<?, ?, ?>) o; Map<C, V> row = Maps.safeGet(rowMap(), cell.getRowKey()); return row != null && Collections2.safeContains(row.entrySet(), Maps.immutableEntry(cell.getColumnKey(), cell.getValue())); } return false; } @Override public boolean remove(@Nullable Object o) { if (o instanceof Cell) { Cell<?, ?, ?> cell = (Cell<?, ?, ?>) o; Map<C, V> row = Maps.safeGet(rowMap(), cell.getRowKey()); return row != null && Collections2.safeRemove(row.entrySet(), Maps.immutableEntry(cell.getColumnKey(), cell.getValue())); } return false; } @Override public void clear() { AbstractTable.this.clear(); } @Override public Iterator<Table.Cell<R, C, V>> iterator() { return cellIterator(); } @Override public int size() { return AbstractTable.this.size(); } } private transient Collection<V> values; @Override public Collection<V> values() { Collection<V> result = values; return (result == null) ? values = createValues() : result; } Collection<V> createValues() { return new Values(); } Iterator<V> valuesIterator() { return new TransformedIterator<Cell<R, C, V>, V>(cellSet().iterator()) { @Override V transform(Cell<R, C, V> cell) { return cell.getValue(); } }; } @WeakOuter class Values extends AbstractCollection<V> { @Override public Iterator<V> iterator() { return valuesIterator(); } @Override public boolean contains(Object o) { return containsValue(o); } @Override public void clear() { AbstractTable.this.clear(); } @Override public int size() { return AbstractTable.this.size(); } } @Override public boolean equals(@Nullable Object obj) { return Tables.equalsImpl(this, obj); } @Override public int hashCode() { return cellSet().hashCode(); } /** * Returns the string representation {@code rowMap().toString()}. */ @Override public String toString() { return rowMap().toString(); } }