AbstractMapクラスはMapインタフェースを実装するクラスのスーパークラスとなる抽象クラスである。内部で定義されているインナークラスについては省略した。コンストラクタはprotectedとなっており，サブクラスからしか呼び出せない。put(K key, V value)メソッドはこのクラスではUnsupportedOperationExceptionをスローする実装となっており，サブクラスでオーバーライドする必要がある。内部の各要素（キーと値のペア）はjava.util.Map.Entry型のオブジェクトで管理されているようだ。
size()メソッドは，entrySet()メソッドで各要素のセットEntrySetを取得し，そのsize()メソッドを呼び出している。さらにisEmpty()メソッドはsize()メソッドの戻り値が0か否かで判定している。
containsValue(Object value)メソッドでは， entrySet()メソッドで各要素のセットEntrySetを取得し ，そのiterator()メソッドでイテレータを取得した上で，保持している要素を順次取り出して，値が一致するものがないかチェックしている。containsKey(Object key)メソッドもほぼ同じ実装であり，こちらはキーを使って検索している。
get(Object key)メソッドでも同じようにentrySet()メソッドで各要素のセットを取得し，そのイテレータを取得した上で順次要素を取り出し，キーが一致するオブジェクトを取得している。 remove(Object key)メソッドでも同様に順次検索を行って，見つかった要素を削除するというロジックである。
putAll(Map m)メソッドでは，引数のmapで与えられたキーと値のペア要素をすべて追加する。引数のマップのentrySet()ですべての要素を取り出し，拡張forループでループさせてすべてのキーと値をput(key, value)メソッドで追加している。
clear()メソッドでは，entrySet()メソッドで保持している要素のセットを取得して，そのclear()メソッドを実行する。
keySet()メソッドでは，メソッド内でAbstractSetを継承した無名インナークラスのインスタンスを作成して，それを返すようになっている。values()メソッドでも，メソッド内でAbstractCollectionを継承した無名インナークラスのインスタンスを作成して，それを返す実装である。なお，entrySet()メソッドは抽象メソッドになっている。
/*
* Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.util;
import java.util.Map.Entry;
public abstract class AbstractMap<K,V> implements Map<K,V> {
protected AbstractMap() {
}
// Query Operations
public int size() {
return entrySet().size();
}
public boolean isEmpty() {
return size() == 0;
}
public boolean containsValue(Object value) {
Iterator<Entry<K,V>> i = entrySet().iterator();
if (value==null) {
while (i.hasNext()) {
Entry<K,V> e = i.next();
if (e.getValue()==null)
return true;
}
} else {
while (i.hasNext()) {
Entry<K,V> e = i.next();
if (value.equals(e.getValue()))
return true;
}
}
return false;
}
public boolean containsKey(Object key) {
Iterator<Map.Entry<K,V>> i = entrySet().iterator();
if (key==null) {
while (i.hasNext()) {
Entry<K,V> e = i.next();
if (e.getKey()==null)
return true;
}
} else {
while (i.hasNext()) {
Entry<K,V> e = i.next();
if (key.equals(e.getKey()))
return true;
}
}
return false;
}
public V get(Object key) {
Iterator<Entry<K,V>> i = entrySet().iterator();
if (key==null) {
while (i.hasNext()) {
Entry<K,V> e = i.next();
if (e.getKey()==null)
return e.getValue();
}
} else {
while (i.hasNext()) {
Entry<K,V> e = i.next();
if (key.equals(e.getKey()))
return e.getValue();
}
}
return null;
}
// Modification Operations
public V put(K key, V value) {
throw new UnsupportedOperationException();
}
public V remove(Object key) {
Iterator<Entry<K,V>> i = entrySet().iterator();
Entry<K,V> correctEntry = null;
if (key==null) {
while (correctEntry==null && i.hasNext()) {
Entry<K,V> e = i.next();
if (e.getKey()==null)
correctEntry = e;
}
} else {
while (correctEntry==null && i.hasNext()) {
Entry<K,V> e = i.next();
if (key.equals(e.getKey()))
correctEntry = e;
}
}
V oldValue = null;
if (correctEntry !=null) {
oldValue = correctEntry.getValue();
i.remove();
}
return oldValue;
}
// Bulk Operations
public void putAll(Map<? extends K, ? extends V> m) {
for (Map.Entry<? extends K, ? extends V> e : m.entrySet())
put(e.getKey(), e.getValue());
}
public void clear() {
entrySet().clear();
}
// Views
transient Set<K> keySet;
transient Collection<V> values;
public Set<K> keySet() {
Set<K> ks = keySet;
if (ks == null) {
ks = new AbstractSet<K>() {
public Iterator<K> iterator() {
return new Iterator<K>() {
private Iterator<Entry<K,V>> i = entrySet().iterator();
public boolean hasNext() {
return i.hasNext();
}
public K next() {
return i.next().getKey();
}
public void remove() {
i.remove();
}
};
}
public int size() {
return AbstractMap.this.size();
}
public boolean isEmpty() {
return AbstractMap.this.isEmpty();
}
public void clear() {
AbstractMap.this.clear();
}
public boolean contains(Object k) {
return AbstractMap.this.containsKey(k);
}
};
keySet = ks;
}
return ks;
}
public Collection<V> values() {
Collection<V> vals = values;
if (vals == null) {
vals = new AbstractCollection<V>() {
public Iterator<V> iterator() {
return new Iterator<V>() {
private Iterator<Entry<K,V>> i = entrySet().iterator();
public boolean hasNext() {
return i.hasNext();
}
public V next() {
return i.next().getValue();
}
public void remove() {
i.remove();
}
};
}
public int size() {
return AbstractMap.this.size();
}
public boolean isEmpty() {
return AbstractMap.this.isEmpty();
}
public void clear() {
AbstractMap.this.clear();
}
public boolean contains(Object v) {
return AbstractMap.this.containsValue(v);
}
};
values = vals;
}
return vals;
}
public abstract Set<Entry<K,V>> entrySet();
// Comparison and hashing
public boolean equals(Object o) {
if (o == this)
return true;
if (!(o instanceof Map))
return false;
Map<?,?> m = (Map<?,?>) o;
if (m.size() != size())
return false;
try {
for (Entry<K, V> e : entrySet()) {
K key = e.getKey();
V value = e.getValue();
if (value == null) {
if (!(m.get(key) == null && m.containsKey(key)))
return false;
} else {
if (!value.equals(m.get(key)))
return false;
}
}
} catch (ClassCastException unused) {
return false;
} catch (NullPointerException unused) {
return false;
}
return true;
}
public int hashCode() {
int h = 0;
for (Entry<K, V> entry : entrySet())
h += entry.hashCode();
return h;
}
public String toString() {
Iterator<Entry<K,V>> i = entrySet().iterator();
if (! i.hasNext())
return "{}";
StringBuilder sb = new StringBuilder();
sb.append('{');
for (;;) {
Entry<K,V> e = i.next();
K key = e.getKey();
V value = e.getValue();
sb.append(key == this ? "(this Map)" : key);
sb.append('=');
sb.append(value == this ? "(this Map)" : value);
if (! i.hasNext())
return sb.append('}').toString();
sb.append(',').append(' ');
}
}
protected Object clone() throws CloneNotSupportedException {
AbstractMap<?,?> result = (AbstractMap<?,?>)super.clone();
result.keySet = null;
result.values = null;
return result;
}
private static boolean eq(Object o1, Object o2) {
return o1 == null ? o2 == null : o1.equals(o2);
}
// Implementation Note: SimpleEntry and SimpleImmutableEntry
// are distinct unrelated classes, even though they share
// some code. Since you can't add or subtract final-ness
// of a field in a subclass, they can't share representations,
// and the amount of duplicated code is too small to warrant
// exposing a common abstract class.
public static class SimpleEntry<K,V>
implements Entry<K,V>, java.io.Serializable
{
省略
}
public static class SimpleImmutableEntry<K,V>
implements Entry<K,V>, java.io.Serializable
{
省略
}
}
* Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.util;
import java.util.Map.Entry;
public abstract class AbstractMap<K,V> implements Map<K,V> {
protected AbstractMap() {
}
// Query Operations
public int size() {
return entrySet().size();
}
public boolean isEmpty() {
return size() == 0;
}
public boolean containsValue(Object value) {
Iterator<Entry<K,V>> i = entrySet().iterator();
if (value==null) {
while (i.hasNext()) {
Entry<K,V> e = i.next();
if (e.getValue()==null)
return true;
}
} else {
while (i.hasNext()) {
Entry<K,V> e = i.next();
if (value.equals(e.getValue()))
return true;
}
}
return false;
}
public boolean containsKey(Object key) {
Iterator<Map.Entry<K,V>> i = entrySet().iterator();
if (key==null) {
while (i.hasNext()) {
Entry<K,V> e = i.next();
if (e.getKey()==null)
return true;
}
} else {
while (i.hasNext()) {
Entry<K,V> e = i.next();
if (key.equals(e.getKey()))
return true;
}
}
return false;
}
public V get(Object key) {
Iterator<Entry<K,V>> i = entrySet().iterator();
if (key==null) {
while (i.hasNext()) {
Entry<K,V> e = i.next();
if (e.getKey()==null)
return e.getValue();
}
} else {
while (i.hasNext()) {
Entry<K,V> e = i.next();
if (key.equals(e.getKey()))
return e.getValue();
}
}
return null;
}
// Modification Operations
public V put(K key, V value) {
throw new UnsupportedOperationException();
}
public V remove(Object key) {
Iterator<Entry<K,V>> i = entrySet().iterator();
Entry<K,V> correctEntry = null;
if (key==null) {
while (correctEntry==null && i.hasNext()) {
Entry<K,V> e = i.next();
if (e.getKey()==null)
correctEntry = e;
}
} else {
while (correctEntry==null && i.hasNext()) {
Entry<K,V> e = i.next();
if (key.equals(e.getKey()))
correctEntry = e;
}
}
V oldValue = null;
if (correctEntry !=null) {
oldValue = correctEntry.getValue();
i.remove();
}
return oldValue;
}
// Bulk Operations
public void putAll(Map<? extends K, ? extends V> m) {
for (Map.Entry<? extends K, ? extends V> e : m.entrySet())
put(e.getKey(), e.getValue());
}
public void clear() {
entrySet().clear();
}
// Views
transient Set<K> keySet;
transient Collection<V> values;
public Set<K> keySet() {
Set<K> ks = keySet;
if (ks == null) {
ks = new AbstractSet<K>() {
public Iterator<K> iterator() {
return new Iterator<K>() {
private Iterator<Entry<K,V>> i = entrySet().iterator();
public boolean hasNext() {
return i.hasNext();
}
public K next() {
return i.next().getKey();
}
public void remove() {
i.remove();
}
};
}
public int size() {
return AbstractMap.this.size();
}
public boolean isEmpty() {
return AbstractMap.this.isEmpty();
}
public void clear() {
AbstractMap.this.clear();
}
public boolean contains(Object k) {
return AbstractMap.this.containsKey(k);
}
};
keySet = ks;
}
return ks;
}
public Collection<V> values() {
Collection<V> vals = values;
if (vals == null) {
vals = new AbstractCollection<V>() {
public Iterator<V> iterator() {
return new Iterator<V>() {
private Iterator<Entry<K,V>> i = entrySet().iterator();
public boolean hasNext() {
return i.hasNext();
}
public V next() {
return i.next().getValue();
}
public void remove() {
i.remove();
}
};
}
public int size() {
return AbstractMap.this.size();
}
public boolean isEmpty() {
return AbstractMap.this.isEmpty();
}
public void clear() {
AbstractMap.this.clear();
}
public boolean contains(Object v) {
return AbstractMap.this.containsValue(v);
}
};
values = vals;
}
return vals;
}
public abstract Set<Entry<K,V>> entrySet();
// Comparison and hashing
public boolean equals(Object o) {
if (o == this)
return true;
if (!(o instanceof Map))
return false;
Map<?,?> m = (Map<?,?>) o;
if (m.size() != size())
return false;
try {
for (Entry<K, V> e : entrySet()) {
K key = e.getKey();
V value = e.getValue();
if (value == null) {
if (!(m.get(key) == null && m.containsKey(key)))
return false;
} else {
if (!value.equals(m.get(key)))
return false;
}
}
} catch (ClassCastException unused) {
return false;
} catch (NullPointerException unused) {
return false;
}
return true;
}
public int hashCode() {
int h = 0;
for (Entry<K, V> entry : entrySet())
h += entry.hashCode();
return h;
}
public String toString() {
Iterator<Entry<K,V>> i = entrySet().iterator();
if (! i.hasNext())
return "{}";
StringBuilder sb = new StringBuilder();
sb.append('{');
for (;;) {
Entry<K,V> e = i.next();
K key = e.getKey();
V value = e.getValue();
sb.append(key == this ? "(this Map)" : key);
sb.append('=');
sb.append(value == this ? "(this Map)" : value);
if (! i.hasNext())
return sb.append('}').toString();
sb.append(',').append(' ');
}
}
protected Object clone() throws CloneNotSupportedException {
AbstractMap<?,?> result = (AbstractMap<?,?>)super.clone();
result.keySet = null;
result.values = null;
return result;
}
private static boolean eq(Object o1, Object o2) {
return o1 == null ? o2 == null : o1.equals(o2);
}
// Implementation Note: SimpleEntry and SimpleImmutableEntry
// are distinct unrelated classes, even though they share
// some code. Since you can't add or subtract final-ness
// of a field in a subclass, they can't share representations,
// and the amount of duplicated code is too small to warrant
// exposing a common abstract class.
public static class SimpleEntry<K,V>
implements Entry<K,V>, java.io.Serializable
{
省略
}
public static class SimpleImmutableEntry<K,V>
implements Entry<K,V>, java.io.Serializable
{
省略
}
}
ＪＹ情報システムズ 