AbstractReferenceMap.java
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com.espertech.esper.collection.apachecommons |
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| Metric | Description | |
|---|---|---|
| DECL_COMMENTS | Comments in declarations |  |
| DOC_COMMENT | Number of javadoc comment lines | |
| COMMENTS | Comment lines | |
| RETURNS | Number of return points from functions | |
| FUNCTIONS | Number of function declarations | |
| INTERFACE_COMPLEXITY | Interface complexity | |
| SIZE | Size of the file in bytes | |
| CYCLOMATIC | Cyclomatic complexity | |
| LINES | Number of lines in the source file | |
| BLOCKS | Number of blocks | |
| LINE_COMMENT | Number of line comments | |
| PARAMS | Number of formal parameter declarations | |
| JAVA0277 | JAVA0277 Iterator.next() implementation does not throw NoSuchElementException | |
| JAVA0128 | JAVA0128 Public constructor in non-public class | |
| JAVA0113 | JAVA0113 Incorrect javadoc: no @author tag | |
| LOOPS | Number of loops | |
| LOGICAL_LINES | Number of statements | |
| LOC | Lines of code | |
| OPERATORS | Number of operators | |
| COMPARISONS | Number of comparison operators | |
| JAVA0034 | JAVA0034 Missing braces in if statement | |
| ELOC | Effective lines of code | |
| PROGRAM_LENGTH | Halstead program length | |
| PROGRAM_VOCAB | Halstead program vocabulary | |
| UNIQUE_OPERANDS | Number of unique operands | |
| JAVA0123 | JAVA0123 Use all three components of for loop | |
| JAVA0254 | JAVA0254 Use enhanced for loop construct instead of Iterator | |
| EXITS | Procedure exits | |
| JAVA0117 | JAVA0117 Missing javadoc: method 'method' | |
| JAVA0114 | JAVA0114 Incorrect javadoc: no @version tag | |
| JAVA0081 | JAVA0081 Boolean literal in comparison | |
| JAVA0242 | JAVA0242 Transient field in non-Serializable class | |
| OPERANDS | Number of operands | |
| JAVA0115 | JAVA0115 Incorrect javadoc: no @throws or @exception tag for 'exception' | |
| UNIQUE_OPERATORS | Number of unique operators | |
| JAVA0150 | JAVA0150 java.lang.Error (or subclass) thrown | |
| JAVA0259 | JAVA0259 Return of collection/array field | |
| JAVA0058 | JAVA0058 Constructor calls super() | |
| PROGRAM_VOLUME | Halstead program volume | |
| JAVA0136 | JAVA0136 N methods defined in class (maximum: M) | |
| JAVA0126 | JAVA0126 Method declares unchecked exception in throws | |
| JAVA0110 | JAVA0110 Incorrect javadoc: no @return tag | |
| JAVA0108 | JAVA0108 Incorrect javadoc: no @param tag for 'parameter' | |
| JAVA0145 | JAVA0145 Tab character used in source file | |
/*
* 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 com.espertech.esper.collection.apachecommons;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.lang.ref.Reference;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.SoftReference;
import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.Collection;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
/**
* An abstract implementation of a hash-based map that allows the entries to
* be removed by the garbage collector.
* <p>
* This class implements all the features necessary for a subclass reference
* hash-based map. Key-value entries are stored in instances of the
* <code>ReferenceEntry</code> class which can be overridden and replaced.
* The iterators can similarly be replaced, without the need to replace the KeySet,
* EntrySet and Values view classes.
* <p>
* Overridable methods are provided to change the default hashing behaviour, and
* to change how entries are added to and removed from the map. Hopefully, all you
* need for unusual subclasses is here.
* <p>
* When you construct an <code>AbstractReferenceMap</code>, you can specify what
* kind of references are used to store the map's keys and values.
* If non-hard references are used, then the garbage collector can remove
* mappings if a key or value becomes unreachable, or if the JVM's memory is
* running low. For information on how the different reference types behave,
* see {@link Reference}.
* <p>
* Different types of references can be specified for keys and values.
* The keys can be configured to be weak but the values hard,
* in which case this class will behave like a
* <a href="http://java.sun.com/j2se/1.4/docs/api/java/util/WeakHashMap.html">
* <code>WeakHashMap</code></a>. However, you can also specify hard keys and
* weak values, or any other combination. The default constructor uses
* hard keys and soft values, providing a memory-sensitive cache.
* <p>
* This {@link Map} implementation does <i>not</i> allow null elements.
* Attempting to add a null key or value to the map will raise a
* <code>NullPointerException</code>.
* <p>
* All the available iterators can be reset back to the start by casting to
* <code>ResettableIterator</code> and calling <code>reset()</code>.
* <p>
* This implementation is not synchronized.
* You can use {@link java.util.Collections#synchronizedMap} to
* provide synchronized access to a <code>ReferenceMap</code>.
*
* @see java.lang.ref.Reference
* @since Commons Collections 3.1 (extracted from ReferenceMap in 3.0)
* @version $Revision$ $Date$
*
* @author Paul Jack
* @author Stephen Colebourne
*/
public abstract class AbstractReferenceMap extends AbstractHashedMap {
/** Constant indicating that hard references should be used */
public static final int HARD = 0;
/** Constant indicating that soft references should be used */
public static final int SOFT = 1;
/** Constant indicating that weak references should be used */
public static final int WEAK = 2;
/**
* The reference type for keys. Must be HARD, SOFT, WEAK.
* @serial
*/
protected int keyType;
/**
* The reference type for values. Must be HARD, SOFT, WEAK.
* @serial
*/
protected int valueType;
/**
* Should the value be automatically purged when the associated key has been collected?
*/
protected boolean purgeValues;
/**
* ReferenceQueue used to eliminate stale mappings.
* See purge.
*/
private transient ReferenceQueue queue;
//-----------------------------------------------------------------------
/**
* Constructor used during deserialization.
*/
protected AbstractReferenceMap() {
super();
}
/**
* Constructs a new empty map with the specified reference types,
* load factor and initial capacity.
*
* @param keyType the type of reference to use for keys;
* must be {@link #HARD}, {@link #SOFT}, {@link #WEAK}
* @param valueType the type of reference to use for values;
* must be {@link #HARD}, {@link #SOFT}, {@link #WEAK}
* @param capacity the initial capacity for the map
* @param loadFactor the load factor for the map
* @param purgeValues should the value be automatically purged when the
* key is garbage collected
*/
protected AbstractReferenceMap(
int keyType, int valueType, int capacity,
float loadFactor, boolean purgeValues) {
super(capacity, loadFactor);
verify("keyType", keyType);
verify("valueType", valueType);
this.keyType = keyType;
this.valueType = valueType;
this.purgeValues = purgeValues;
}
/**
* Initialise this subclass during construction, cloning or deserialization.
*/
protected void init() {
queue = new ReferenceQueue();
}
//-----------------------------------------------------------------------
/**
* Checks the type int is a valid value.
*
* @param name the name for error messages
* @param type the type value to check
* @throws IllegalArgumentException if the value if invalid
*/
private static void verify(String name, int type) {
if ((type < HARD) || (type > WEAK)) {
throw new IllegalArgumentException(name + " must be HARD, SOFT, WEAK.");
}
}
//-----------------------------------------------------------------------
/**
* Gets the size of the map.
*
* @return the size
*/
public int size() {
purgeBeforeRead();
return super.size();
}
/**
* Checks whether the map is currently empty.
*
* @return true if the map is currently size zero
*/
public boolean isEmpty() {
purgeBeforeRead();
return super.isEmpty();
}
/**
* Checks whether the map contains the specified key.
*
* @param key the key to search for
* @return true if the map contains the key
*/
public boolean containsKey(Object key) {
purgeBeforeRead();
Entry entry = getEntry(key);
if (entry == null) {
return false;
}
return (entry.getValue() != null);
}
/**
* Checks whether the map contains the specified value.
*
* @param value the value to search for
* @return true if the map contains the value
*/
public boolean containsValue(Object value) {
purgeBeforeRead();
if (value == null) {
return false;
}
return super.containsValue(value);
}
/**
* Gets the value mapped to the key specified.
*
* @param key the key
* @return the mapped value, null if no match
*/
public Object get(Object key) {
purgeBeforeRead();
Entry entry = getEntry(key);
if (entry == null) {
return null;
}
return entry.getValue();
}
/**
* Puts a key-value mapping into this map.
* Neither the key nor the value may be null.
*
* @param key the key to add, must not be null
* @param value the value to add, must not be null
* @return the value previously mapped to this key, null if none
* @throws NullPointerException if either the key or value is null
*/
public Object put(Object key, Object value) {
if (key == null) {
throw new NullPointerException("null keys not allowed");
}
if (value == null) {
throw new NullPointerException("null values not allowed");
}
purgeBeforeWrite();
return super.put(key, value);
}
/**
* Removes the specified mapping from this map.
*
* @param key the mapping to remove
* @return the value mapped to the removed key, null if key not in map
*/
public Object remove(Object key) {
if (key == null) {
return null;
}
purgeBeforeWrite();
return super.remove(key);
}
/**
* Clears this map.
*/
public void clear() {
super.clear();
while (queue.poll() != null) {} // drain the queue
}
//-----------------------------------------------------------------------
/**
* Gets a MapIterator over the reference map.
* The iterator only returns valid key/value pairs.
*
* @return a map iterator
*/
public MapIterator mapIterator() {
return new ReferenceMapIterator(this);
}
/**
* Returns a set view of this map's entries.
* An iterator returned entry is valid until <code>next()</code> is called again.
* The <code>setValue()</code> method on the <code>toArray</code> entries has no effect.
*
* @return a set view of this map's entries
*/
public Set entrySet() {
if (entrySet == null) {
entrySet = new ReferenceEntrySet(this);
}
return entrySet;
}
/**
* Returns a set view of this map's keys.
*
* @return a set view of this map's keys
*/
public Set keySet() {
if (keySet == null) {
keySet = new ReferenceKeySet(this);
}
return keySet;
}
/**
* Returns a collection view of this map's values.
*
* @return a set view of this map's values
*/
public Collection values() {
if (values == null) {
values = new ReferenceValues(this);
}
return values;
}
//-----------------------------------------------------------------------
/**
* Purges stale mappings from this map before read operations.
* <p>
* This implementation calls {@link #purge()} to maintain a consistent state.
*/
protected void purgeBeforeRead() {
purge();
}
/**
* Purges stale mappings from this map before write operations.
* <p>
* This implementation calls {@link #purge()} to maintain a consistent state.
*/
protected void purgeBeforeWrite() {
purge();
}
/**
* Purges stale mappings from this map.
* <p>
* Note that this method is not synchronized! Special
* care must be taken if, for instance, you want stale
* mappings to be removed on a periodic basis by some
* background thread.
*/
protected void purge() {
Reference ref = queue.poll();
while (ref != null) {
purge(ref);
ref = queue.poll();
}
}
/**
* Purges the specified reference.
*
* @param ref the reference to purge
*/
protected void purge(Reference ref) {
// The hashCode of the reference is the hashCode of the
// mapping key, even if the reference refers to the
// mapping value...
int hash = ref.hashCode();
int index = hashIndex(hash, data.length);
HashEntry previous = null;
HashEntry entry = data[index];
while (entry != null) {
if (((ReferenceEntry) entry).purge(ref)) {
if (previous == null) {
data[index] = entry.next;
} else {
previous.next = entry.next;
}
this.size--;
return;
}
previous = entry;
entry = entry.next;
}
}
//-----------------------------------------------------------------------
/**
* Gets the entry mapped to the key specified.
*
* @param key the key
* @return the entry, null if no match
*/
protected HashEntry getEntry(Object key) {
if (key == null) {
return null;
} else {
return super.getEntry(key);
}
}
/**
* Gets the hash code for a MapEntry.
* Subclasses can override this, for example to use the identityHashCode.
*
* @param key the key to get a hash code for, may be null
* @param value the value to get a hash code for, may be null
* @return the hash code, as per the MapEntry specification
*/
protected int hashEntry(Object key, Object value) {
return (key == null ? 0 : key.hashCode()) ^
(value == null ? 0 : value.hashCode());
}
/**
* Compares two keys, in internal converted form, to see if they are equal.
* <p>
* This implementation converts the key from the entry to a real reference
* before comparison.
*
* @param key1 the first key to compare passed in from outside
* @param key2 the second key extracted from the entry via <code>entry.key</code>
* @return true if equal
*/
protected boolean isEqualKey(Object key1, Object key2) {
key2 = (keyType > HARD ? ((Reference) key2).get() : key2);
return (key1 == key2 || key1.equals(key2));
}
/**
* Creates a ReferenceEntry instead of a HashEntry.
*
* @param next the next entry in sequence
* @param hashCode the hash code to use
* @param key the key to store
* @param value the value to store
* @return the newly created entry
*/
protected HashEntry createEntry(HashEntry next, int hashCode, Object key, Object value) {
return new ReferenceEntry(this, next, hashCode, key, value);
}
/**
* Creates an entry set iterator.
*
* @return the entrySet iterator
*/
protected Iterator createEntrySetIterator() {
return new ReferenceEntrySetIterator(this);
}
/**
* Creates an key set iterator.
*
* @return the keySet iterator
*/
protected Iterator createKeySetIterator() {
return new ReferenceKeySetIterator(this);
}
/**
* Creates an values iterator.
*
* @return the values iterator
*/
protected Iterator createValuesIterator() {
return new ReferenceValuesIterator(this);
}
//-----------------------------------------------------------------------
/**
* EntrySet implementation.
*/
static class ReferenceEntrySet extends EntrySet {
protected ReferenceEntrySet(AbstractHashedMap parent) {
super(parent);
}
public Object[] toArray() {
return toArray(new Object[0]);
}
public Object[] toArray(Object[] arr) {
// special implementation to handle disappearing entries
ArrayList list = new ArrayList();
Iterator iterator = iterator();
while (iterator.hasNext()) {
Entry e = (Entry) iterator.next();
list.add(new DefaultMapEntry(e.getKey(), e.getValue()));
}
return list.toArray(arr);
}
}
//-----------------------------------------------------------------------
/**
* KeySet implementation.
*/
static class ReferenceKeySet extends KeySet {
protected ReferenceKeySet(AbstractHashedMap parent) {
super(parent);
}
public Object[] toArray() {
return toArray(new Object[0]);
}
public Object[] toArray(Object[] arr) {
// special implementation to handle disappearing keys
List list = new ArrayList(parent.size());
for (Iterator it = iterator(); it.hasNext(); ) {
list.add(it.next());
}
return list.toArray(arr);
}
}
//-----------------------------------------------------------------------
/**
* Values implementation.
*/
static class ReferenceValues extends Values {
protected ReferenceValues(AbstractHashedMap parent) {
super(parent);
}
public Object[] toArray() {
return toArray(new Object[0]);
}
public Object[] toArray(Object[] arr) {
// special implementation to handle disappearing values
List list = new ArrayList(parent.size());
for (Iterator it = iterator(); it.hasNext(); ) {
list.add(it.next());
}
return list.toArray(arr);
}
}
//-----------------------------------------------------------------------
/**
* A MapEntry implementation for the map.
* <p>
* If getKey() or getValue() returns null, it means
* the mapping is stale and should be removed.
*
* @since Commons Collections 3.1
*/
protected static class ReferenceEntry extends HashEntry {
/** The parent map */
protected final AbstractReferenceMap parent;
/**
* Creates a new entry object for the ReferenceMap.
*
* @param parent the parent map
* @param next the next entry in the hash bucket
* @param hashCode the hash code of the key
* @param key the key
* @param value the value
*/
public ReferenceEntry(AbstractReferenceMap parent, HashEntry next, int hashCode, Object key, Object value) {
super(next, hashCode, null, null);
this.parent = parent;
this.key = toReference(parent.keyType, key, hashCode);
this.value = toReference(parent.valueType, value, hashCode); // the key hashCode is passed in deliberately
}
/**
* Gets the key from the entry.
* This method dereferences weak and soft keys and thus may return null.
*
* @return the key, which may be null if it was garbage collected
*/
public Object getKey() {
return (parent.keyType > HARD) ? ((Reference) key).get() : key;
}
/**
* Gets the value from the entry.
* This method dereferences weak and soft value and thus may return null.
*
* @return the value, which may be null if it was garbage collected
*/
public Object getValue() {
return (parent.valueType > HARD) ? ((Reference) value).get() : value;
}
/**
* Sets the value of the entry.
*
* @param obj the object to store
* @return the previous value
*/
public Object setValue(Object obj) {
Object old = getValue();
if (parent.valueType > HARD) {
((Reference)value).clear();
}
value = toReference(parent.valueType, obj, hashCode);
return old;
}
/**
* Compares this map entry to another.
* <p>
* This implementation uses <code>isEqualKey</code> and
* <code>isEqualValue</code> on the main map for comparison.
*
* @param obj the other map entry to compare to
* @return true if equal, false if not
*/
public boolean equals(Object obj) {
if (obj == this) {
return true;
}
if (obj instanceof Map.Entry == false) {
return false;
}
Map.Entry entry = (Map.Entry)obj;
Object entryKey = entry.getKey(); // convert to hard reference
Object entryValue = entry.getValue(); // convert to hard reference
if ((entryKey == null) || (entryValue == null)) {
return false;
}
// compare using map methods, aiding identity subclass
// note that key is direct access and value is via method
return parent.isEqualKey(entryKey, key) &&
parent.isEqualValue(entryValue, getValue());
}
/**
* Gets the hashcode of the entry using temporary hard references.
* <p>
* This implementation uses <code>hashEntry</code> on the main map.
*
* @return the hashcode of the entry
*/
public int hashCode() {
return parent.hashEntry(getKey(), getValue());
}
/**
* Constructs a reference of the given type to the given referent.
* The reference is registered with the queue for later purging.
*
* @param type HARD, SOFT or WEAK
* @param referent the object to refer to
* @param hash the hash code of the <i>key</i> of the mapping;
* this number might be different from referent.hashCode() if
* the referent represents a value and not a key
* @return reference
*/
protected Object toReference(int type, Object referent, int hash) {
switch (type) {
case HARD: return referent;
case SOFT: return new SoftRef(hash, referent, parent.queue);
case WEAK: return new WeakRef(hash, referent, parent.queue);
default: throw new Error();
}
}
/**
* Purges the specified reference
* @param ref the reference to purge
* @return true or false
*/
boolean purge(Reference ref) {
boolean r = (parent.keyType > HARD) && (key == ref);
r = r || ((parent.valueType > HARD) && (value == ref));
if (r) {
if (parent.keyType > HARD) {
((Reference)key).clear();
}
if (parent.valueType > HARD) {
((Reference)value).clear();
} else if (parent.purgeValues) {
value = null;
}
}
return r;
}
/**
* Gets the next entry in the bucket.
*
* @return the next entry in the bucket
*/
protected ReferenceEntry next() {
return (ReferenceEntry) next;
}
}
//-----------------------------------------------------------------------
/**
* The EntrySet iterator.
*/
static class ReferenceEntrySetIterator implements Iterator {
/** The parent map */
final AbstractReferenceMap parent;
// These fields keep track of where we are in the table.
int index;
ReferenceEntry entry;
ReferenceEntry previous;
// These Object fields provide hard references to the
// current and next entry; this assures that if hasNext()
// returns true, next() will actually return a valid element.
Object nextKey, nextValue;
Object currentKey, currentValue;
int expectedModCount;
public ReferenceEntrySetIterator(AbstractReferenceMap parent) {
super();
this.parent = parent;
index = (parent.size() != 0 ? parent.data.length : 0);
// have to do this here! size() invocation above
// may have altered the modCount.
expectedModCount = parent.modCount;
}
public boolean hasNext() {
checkMod();
while (nextNull()) {
ReferenceEntry e = entry;
int i = index;
while ((e == null) && (i > 0)) {
i--;
e = (ReferenceEntry) parent.data[i];
}
entry = e;
index = i;
if (e == null) {
currentKey = null;
currentValue = null;
return false;
}
nextKey = e.getKey();
nextValue = e.getValue();
if (nextNull()) {
entry = entry.next();
}
}
return true;
}
private void checkMod() {
if (parent.modCount != expectedModCount) {
throw new ConcurrentModificationException();
}
}
private boolean nextNull() {
return (nextKey == null) || (nextValue == null);
}
protected ReferenceEntry nextEntry() {
checkMod();
if (nextNull() && !hasNext()) {
throw new NoSuchElementException();
}
previous = entry;
entry = entry.next();
currentKey = nextKey;
currentValue = nextValue;
nextKey = null;
nextValue = null;
return previous;
}
protected ReferenceEntry currentEntry() {
checkMod();
return previous;
}
public Object next() {
return nextEntry();
}
public void remove() {
checkMod();
if (previous == null) {
throw new IllegalStateException();
}
parent.remove(currentKey);
previous = null;
currentKey = null;
currentValue = null;
expectedModCount = parent.modCount;
}
}
/**
* The keySet iterator.
*/
static class ReferenceKeySetIterator extends ReferenceEntrySetIterator {
ReferenceKeySetIterator(AbstractReferenceMap parent) {
super(parent);
}
public Object next() {
return nextEntry().getKey();
}
}
/**
* The values iterator.
*/
static class ReferenceValuesIterator extends ReferenceEntrySetIterator {
ReferenceValuesIterator(AbstractReferenceMap parent) {
super(parent);
}
public Object next() {
return nextEntry().getValue();
}
}
/**
* The MapIterator implementation.
*/
static class ReferenceMapIterator extends ReferenceEntrySetIterator implements MapIterator {
protected ReferenceMapIterator(AbstractReferenceMap parent) {
super(parent);
}
public Object next() {
return nextEntry().getKey();
}
public Object getKey() {
HashEntry current = currentEntry();
if (current == null) {
throw new IllegalStateException(AbstractHashedMap.GETKEY_INVALID);
}
return current.getKey();
}
public Object getValue() {
HashEntry current = currentEntry();
if (current == null) {
throw new IllegalStateException(AbstractHashedMap.GETVALUE_INVALID);
}
return current.getValue();
}
public Object setValue(Object value) {
HashEntry current = currentEntry();
if (current == null) {
throw new IllegalStateException(AbstractHashedMap.SETVALUE_INVALID);
}
return current.setValue(value);
}
}
//-----------------------------------------------------------------------
// These two classes store the hashCode of the key of
// of the mapping, so that after they're dequeued a quick
// lookup of the bucket in the table can occur.
/**
* A soft reference holder.
*/
static class SoftRef extends SoftReference {
/** the hashCode of the key (even if the reference points to a value) */
private int hash;
public SoftRef(int hash, Object r, ReferenceQueue q) {
super(r, q);
this.hash = hash;
}
public int hashCode() {
return hash;
}
}
/**
* A weak reference holder.
*/
static class WeakRef extends WeakReference {
/** the hashCode of the key (even if the reference points to a value) */
private int hash;
public WeakRef(int hash, Object r, ReferenceQueue q) {
super(r, q);
this.hash = hash;
}
public int hashCode() {
return hash;
}
}
//-----------------------------------------------------------------------
/**
* Replaces the superclass method to store the state of this class.
* <p>
* Serialization is not one of the JDK's nicest topics. Normal serialization will
* initialise the superclass before the subclass. Sometimes however, this isn't
* what you want, as in this case the <code>put()</code> method on read can be
* affected by subclass state.
* <p>
* The solution adopted here is to serialize the state data of this class in
* this protected method. This method must be called by the
* <code>writeObject()</code> of the first serializable subclass.
* <p>
* Subclasses may override if they have a specific field that must be present
* on read before this implementation will work. Generally, the read determines
* what must be serialized here, if anything.
*
* @param out the output stream
*/
protected void doWriteObject(ObjectOutputStream out) throws IOException {
out.writeInt(keyType);
out.writeInt(valueType);
out.writeBoolean(purgeValues);
out.writeFloat(loadFactor);
out.writeInt(data.length);
for (MapIterator it = mapIterator(); it.hasNext();) {
out.writeObject(it.next());
out.writeObject(it.getValue());
}
out.writeObject(null); // null terminate map
// do not call super.doWriteObject() as code there doesn't work for reference map
}
/**
* Replaces the superclassm method to read the state of this class.
* <p>
* Serialization is not one of the JDK's nicest topics. Normal serialization will
* initialise the superclass before the subclass. Sometimes however, this isn't
* what you want, as in this case the <code>put()</code> method on read can be
* affected by subclass state.
* <p>
* The solution adopted here is to deserialize the state data of this class in
* this protected method. This method must be called by the
* <code>readObject()</code> of the first serializable subclass.
* <p>
* Subclasses may override if the subclass has a specific field that must be present
* before <code>put()</code> or <code>calculateThreshold()</code> will work correctly.
*
* @param in the input stream
*/
protected void doReadObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
this.keyType = in.readInt();
this.valueType = in.readInt();
this.purgeValues = in.readBoolean();
this.loadFactor = in.readFloat();
int capacity = in.readInt();
init();
data = new HashEntry[capacity];
while (true) {
Object key = in.readObject();
if (key == null) {
break;
}
Object value = in.readObject();
put(key, value);
}
threshold = calculateThreshold(data.length, loadFactor);
// do not call super.doReadObject() as code there doesn't work for reference map
}
}
The table below shows all metrics for AbstractReferenceMap.java.
| Metric | Value | Description | |
|---|---|---|---|
| BLOCKS | 110.00 | Number of blocks | |
| BLOCK_COMMENT | 16.00 | Number of block comment lines | |
| COMMENTS | 417.00 | Comment lines | |
| COMMENT_DENSITY | 1.19 | Comment density | |
| COMPARISONS | 63.00 | Number of comparison operators | |
| CYCLOMATIC | 128.00 | Cyclomatic complexity | |
| DECL_COMMENTS | 76.00 | Comments in declarations | |
| DOC_COMMENT | 369.00 | Number of javadoc comment lines | |
| ELOC | 349.00 | Effective lines of code | |
| EXEC_COMMENTS | 8.00 | Comments in executable code | |
| EXITS | 60.00 | Procedure exits | |
| FUNCTIONS | 68.00 | Number of function declarations | |
| HALSTEAD_DIFFICULTY | 80.58 | Halstead difficulty | |
| HALSTEAD_EFFORT | 0.00 | Halstead effort | |
| INTERFACE_COMPLEXITY | 160.00 | Interface complexity | |
| JAVA0001 | 0.00 | JAVA0001 Package name does not contain only lower case letters | |
| JAVA0002 | 0.00 | JAVA0002 Package name does not begin with a top level domain name or country code | |
| JAVA0003 | 0.00 | JAVA0003 Minimize use of on-demand (.*) imports | |
| JAVA0004 | 0.00 | JAVA0004 Unnecessary import from java.lang | |
| JAVA0005 | 0.00 | JAVA0005 Imports not in specified order | |
| JAVA0006 | 0.00 | JAVA0006 Empty finally block | |
| JAVA0007 | 0.00 | JAVA0007 Should not declare public field | |
| JAVA0008 | 0.00 | JAVA0008 Empty catch block | |
| JAVA0009 | 0.00 | JAVA0009 Protected member in final class | |
| JAVA0010 | 0.00 | JAVA0010 Non-instantiable class does not contain a non-private static member | |
| JAVA0011 | 1.00 | JAVA0011 Abstract class does not contain an abstract method | |
| JAVA0012 | 0.00 | JAVA0012 Non-constructor method with same name as declaring class | |
| JAVA0013 | 0.00 | JAVA0013 Non-blank final field is not static | |
| JAVA0014 | 0.00 | JAVA0014 Class with only static members has non-private constructor | |
| JAVA0015 | 0.00 | JAVA0015 Package class contains public nested type | |
| JAVA0016 | 0.00 | JAVA0016 Abstract class contains public constructor | |
| JAVA0017 | 0.00 | JAVA0017 Class name does not have required form | |
| JAVA0018 | 0.00 | JAVA0018 Method name does not have required form | |
| JAVA0019 | 0.00 | JAVA0019 Interface name does not have required form | |
| JAVA0020 | 0.00 | JAVA0020 Field name does not have required form | |
| JAVA0021 | 0.00 | JAVA0021 Interface method name does not have required form | |
| JAVA0022 | 0.00 | JAVA0022 Static final field name does not have required form | |
| JAVA0023 | 0.00 | JAVA0023 Empty finalize method | |
| JAVA0024 | 0.00 | JAVA0024 Empty class | |
| JAVA0025 | 0.00 | JAVA0025 Method override is empty | |
| JAVA0026 | 0.00 | JAVA0026 Finalize method with parameters | |
| JAVA0029 | 0.00 | JAVA0029 Private method not used | |
| JAVA0030 | 0.00 | JAVA0030 Private field not used | |
| JAVA0031 | 0.00 | JAVA0031 Case statement not properly closed | |
| JAVA0032 | 0.00 | JAVA0032 Switch statement missing default | |
| JAVA0033 | 0.00 | JAVA0033 default: not last case in switch statement | |
| JAVA0034 | 0.00 | JAVA0034 Missing braces in if statement | |
| JAVA0035 | 0.00 | JAVA0035 Missing braces in for statement | |
| JAVA0036 | 0.00 | JAVA0036 Missing braces in while statement | |
| JAVA0038 | 0.00 | JAVA0038 Non-case label in switch statement | |
| JAVA0039 | 0.00 | JAVA0039 Break statement with label | |
| JAVA0040 | 0.00 | JAVA0040 Switch statement contains N cases (maximum: M) | |
| JAVA0041 | 0.00 | JAVA0041 Nested synchronized block | |
| JAVA0042 | 0.00 | JAVA0042 Empty synchronized statement | |
| JAVA0043 | 0.00 | JAVA0043 Inner class does not use outer class | |
| JAVA0044 | 0.00 | JAVA0044 Serializable class with no instance variables | |
| JAVA0045 | 0.00 | JAVA0045 Serializable class with only transient fields | |
| JAVA0046 | 0.00 | JAVA0046 Name of class not derived from Exception ends with 'Exception' | |
| JAVA0047 | 0.00 | JAVA0047 Serializable class derives from invalid base class | |
| JAVA0048 | 0.00 | JAVA0048 Name of class derived from Exception does not end with 'Exception' | |
| JAVA0049 | 0.00 | JAVA0049 Nested block at depth N (maximum: M) | |
| JAVA0050 | 0.00 | JAVA0050 Class derives from java.lang.Error | |
| JAVA0051 | 0.00 | JAVA0051 Class derives from java.lang.RuntimeException | |
| JAVA0052 | 0.00 | JAVA0052 Class derives from java.lang.Throwable | |
| JAVA0053 | 0.00 | JAVA0053 Unused label | |
| JAVA0054 | 0.00 | JAVA0054 Inheritance depth N exceeds maximum M | |
| JAVA0055 | 0.00 | JAVA0055 Class should be interface | |
| JAVA0056 | 0.00 | JAVA0056 Unnecessary abstract modifier for interface or annotation | |
| JAVA0057 | 0.00 | JAVA0057 Unnecessary default constructor | |
| JAVA0058 | 2.00 | JAVA0058 Constructor calls super() | |
| JAVA0059 | 0.00 | JAVA0059 Method override only calls super() | |
| JAVA0061 | 0.00 | JAVA0061 Inaccessible member in anonymous class | |
| JAVA0062 | 0.00 | JAVA0062 Public class missing public member or protected constructor | |
| JAVA0063 | 0.00 | JAVA0063 Identifier name should not contain '$' | |
| JAVA0064 | 0.00 | JAVA0064 N variations of identifier name (maximum: M) | |
| JAVA0065 | 0.00 | JAVA0065 Unnecessary final modifier for method in final class | |
| JAVA0066 | 0.00 | JAVA0066 Unnecessary modifier for interface nested type | |
| JAVA0067 | 0.00 | JAVA0067 Array descriptor on identifier name | |
| JAVA0068 | 0.00 | JAVA0068 Modifiers not declared in recommended order | |
| JAVA0071 | 0.00 | JAVA0071 Strings compared with == | |
| JAVA0073 | 0.00 | JAVA0073 Integer division in floating-point context | |
| JAVA0074 | 0.00 | JAVA0074 Use of Object.notify() | |
| JAVA0075 | 0.00 | JAVA0075 Method parameter hides field | |
| JAVA0076 | 0.00 | JAVA0076 Use of magic number | |
| JAVA0077 | 0.00 | JAVA0077 Private field not used in declaring class | |
| JAVA0078 | 0.00 | JAVA0078 Floating point values compared with == | |
| JAVA0079 | 0.00 | JAVA0079 Use of instance to reference static member | |
| JAVA0080 | 0.00 | JAVA0080 Import declaration not used | |
| JAVA0081 | 1.00 | JAVA0081 Boolean literal in comparison | |
| JAVA0082 | 0.00 | JAVA0082 Unnecessary widening cast | |
| JAVA0083 | 0.00 | JAVA0083 Unnecessary instanceof test | |
| JAVA0084 | 0.00 | JAVA0084 Should use compound assignment operator | |
| JAVA0085 | 0.00 | JAVA0085 Use of sun.* class | |
| JAVA0087 | 0.00 | JAVA0087 Use of Thread.sleep() | |
| JAVA0089 | 0.00 | JAVA0089 Use of restricted package | |
| JAVA0092 | 0.00 | JAVA0092 Use of restricted type | |
| JAVA0093 | 0.00 | JAVA0093 Redundant assignment | |
| JAVA0094 | 0.00 | JAVA0094 Field hides a superclass field | |
| JAVA0095 | 0.00 | JAVA0095 Uninitialized private field | |
| JAVA0096 | 0.00 | JAVA0096 Field in nested class hides outer field | |
| JAVA0098 | 2.00 | JAVA0098 Minimize use of implicit field initializers | |
| JAVA0100 | 0.00 | JAVA0100 Class contains N non-final fields (maximum: M) | |
| JAVA0101 | 0.00 | JAVA0101 Unnecessary modifier for field in interface | |
| JAVA0102 | 0.00 | JAVA0102 Last statement in finalize() not super.finalize() | |
| JAVA0103 | 0.00 | JAVA0103 Explicit call to finalize() | |
| JAVA0104 | 0.00 | JAVA0104 finalize() only calls super.finalize() | |
| JAVA0105 | 0.00 | JAVA0105 Duplicate import declaration | |
| JAVA0106 | 0.00 | JAVA0106 Unnecessary import from current package | |
| JAVA0108 | 0.00 | JAVA0108 Incorrect javadoc: no @param tag for 'parameter' | |
| JAVA0109 | 0.00 | JAVA0109 Incorrect javadoc: no parameter 'parameter' | |
| JAVA0110 | 0.00 | JAVA0110 Incorrect javadoc: no @return tag | |
| JAVA0111 | 0.00 | JAVA0111 Incorrect javadoc: @return tag for void method | |
| JAVA0112 | 0.00 | JAVA0112 Incorrect javadoc: no exception 'exception' in throws | |
| JAVA0113 | 10.00 | JAVA0113 Incorrect javadoc: no @author tag | |
| JAVA0114 | 10.00 | JAVA0114 Incorrect javadoc: no @version tag | |
| JAVA0115 | 3.00 | JAVA0115 Incorrect javadoc: no @throws or @exception tag for 'exception' | |
| JAVA0116 | 0.00 | JAVA0116 Missing javadoc: field 'field' | |
| JAVA0117 | 9.00 | JAVA0117 Missing javadoc: method 'method' | |
| JAVA0118 | 0.00 | JAVA0118 Missing javadoc: type 'type' | |
| JAVA0119 | 0.00 | JAVA0119 Control variable changed within body of for loop | |
| JAVA0123 | 3.00 | JAVA0123 Use all three components of for loop | |
| JAVA0125 | 0.00 | JAVA0125 Continue statement with label | |
| JAVA0126 | 0.00 | JAVA0126 Method declares unchecked exception in throws | |
| JAVA0128 | 4.00 | JAVA0128 Public constructor in non-public class | |
| JAVA0130 | 0.00 | JAVA0130 Non-static method does not use instance fields | |
| JAVA0131 | 0.00 | JAVA0131 Compatible method does not override base | |
| JAVA0132 | 0.00 | JAVA0132 Method overload with compatible signature | |
| JAVA0133 | 0.00 | JAVA0133 Non-synchronized method overrides synchronized method | |
| JAVA0135 | 2.00 | JAVA0135 Only one of Object.equals and Object.hashCode defined: missing 'method' | |
| JAVA0136 | 1.00 | JAVA0136 N methods defined in class (maximum: M) | |
| JAVA0137 | 0.00 | JAVA0137 Non-abstract class missing constructor | |
| JAVA0138 | 0.00 | JAVA0138 N parameters defined for method (maximum: M) | |
| JAVA0139 | 0.00 | JAVA0139 Definition of main other than public static void main(java.lang.String[]) | |
| JAVA0141 | 0.00 | JAVA0141 Unnecessary modifier for method in interface | |
| JAVA0143 | 0.00 | JAVA0143 Synchronized method | |
| JAVA0144 | 0.00 | JAVA0144 Line exceeds maximum M characters | |
| JAVA0145 | 0.00 | JAVA0145 Tab character used in source file | |
| JAVA0150 | 1.00 | JAVA0150 java.lang.Error (or subclass) thrown | |
| JAVA0153 | 0.00 | JAVA0153 Inefficient conversion of integer to string | |
| JAVA0159 | 0.00 | JAVA0159 Inefficient conversion of string to integer | |
| JAVA0160 | 0.00 | JAVA0160 Method does not throw specified exception | |
| JAVA0161 | 0.00 | JAVA0161 Conditional wait() not in loop | |
| JAVA0163 | 0.00 | JAVA0163 Empty statement | |
| JAVA0165 | 0.00 | JAVA0165 Conflicting return statement in finally block | |
| JAVA0166 | 0.00 | JAVA0166 Generic exception caught | |
| JAVA0167 | 0.00 | JAVA0167 ThreadDeath not rethrown | |
| JAVA0169 | 0.00 | JAVA0169 Unnecessary catch block: exception 'exception' | |
| JAVA0170 | 0.00 | JAVA0170 Caught exception not derived from java.lang.Exception | |
| JAVA0171 | 0.00 | JAVA0171 Unused local variable | |
| JAVA0173 | 0.00 | JAVA0173 Unused method parameter | |
| JAVA0174 | 0.00 | JAVA0174 Assigned local variable never used | |
| JAVA0175 | 0.00 | JAVA0175 Successive assignment to variable | |
| JAVA0176 | 0.00 | JAVA0176 Local variable name does not have required form | |
| JAVA0177 | 0.00 | JAVA0177 Variable declaration missing initializer | |
| JAVA0179 | 0.00 | JAVA0179 Local variable hides visible field | |
| JAVA0233 | 0.00 | JAVA0233 Definition of serialVersionUID other than 'private static final long serialVersionUID' | |
| JAVA0234 | 0.00 | JAVA0234 Class is Serializable but does not define serialVersionUID | |
| JAVA0235 | 0.00 | JAVA0235 Class defines serialVersionUID but does not implement Serializable | |
| JAVA0236 | 0.00 | JAVA0236 Attempt to clone an object which does not implement Cloneable | |
| JAVA0237 | 0.00 | JAVA0237 Class implements Cloneable but does not have public clone method | |
| JAVA0238 | 0.00 | JAVA0238 Clone method does not call super.clone() | |
| JAVA0239 | 0.00 | JAVA0239 Class declares 'readObject' or 'writeObject' but does not implement Serializable | |
| JAVA0240 | 0.00 | JAVA0240 Serializable class which declares readObject or writeObject but not both | |
| JAVA0241 | 0.00 | JAVA0241 'readObject' or 'writeObject' should be declared private in Serializable class | |
| JAVA0242 | 1.00 | JAVA0242 Transient field in non-Serializable class | |
| JAVA0243 | 0.00 | JAVA0243 'readResolve' or 'writeReplace' should be declared private or protected | |
| JAVA0244 | 0.00 | JAVA0244 Field or method name in subclass differs only by case from inherited field or method | |
| JAVA0245 | 0.00 | JAVA0245 JUnit TestCase with non-trivial constructor | |
| JAVA0246 | 0.00 | JAVA0246 JUnit assertXXX statement missing message parameter | |
| JAVA0247 | 0.00 | JAVA0247 JUnit 'setUp()' and 'tearDown()' should call super method | |
| JAVA0248 | 0.00 | JAVA0248 JUnit method 'setUp' or 'tearDown' with incorrect signature | |
| JAVA0249 | 0.00 | JAVA0249 JUnit TestCase 'suite()' should be declared static | |
| JAVA0250 | 0.00 | JAVA0250 JUnit TestCase declares testXXX method with incorrect signature | |
| JAVA0251 | 0.00 | JAVA0251 Use '%n' for line breaks in printf/format for platform independence | |
| JAVA0252 | 0.00 | JAVA0252 'enum' is a Java 1.5 reserved word | |
| JAVA0253 | 0.00 | JAVA0253 Not all enum constants consumed in switch statement | |
| JAVA0254 | 3.00 | JAVA0254 Use enhanced for loop construct instead of Iterator | |
| JAVA0255 | 0.00 | JAVA0255 Result of method invocation not used | |
| JAVA0256 | 0.00 | JAVA0256 Assignment of external collection/array to field | |
| JAVA0257 | 0.00 | JAVA0257 Use of 'Constant Interface' anti-pattern | |
| JAVA0258 | 1.00 | JAVA0258 Implement Iterable for foreach compatibility | |
| JAVA0259 | 3.00 | JAVA0259 Return of collection/array field | |
| JAVA0260 | 0.00 | JAVA0260 Use 'enum' instead of Enumerated Type pattern | |
| JAVA0261 | 0.00 | JAVA0261 Use specialized Enum collection types | |
| JAVA0262 | 0.00 | JAVA0262 Use of char in integer context | |
| JAVA0263 | 0.00 | JAVA0263 Long literal ends with 'l' instead of 'L' | |
| JAVA0264 | 0.00 | JAVA0264 Integer math in long context - check for overflow | |
| JAVA0265 | 0.00 | JAVA0265 Use of Throwable.printStackTrace() | |
| JAVA0266 | 0.00 | JAVA0266 Use of System.out | |
| JAVA0267 | 0.00 | JAVA0267 Use of System.err | |
| JAVA0269 | 0.00 | JAVA0269 Contents of StringBuffer never used | |
| JAVA0270 | 0.00 | JAVA0270 Use Java 5.0 enhanced for loop construct to iterate over all elements in an array | |
| JAVA0271 | 0.00 | JAVA0271 Minimize use of on-demand (.*) static imports | |
| JAVA0272 | 0.00 | JAVA0272 Thread.run() called | |
| JAVA0273 | 0.00 | JAVA0273 Non-final derivative of Thread calls start() in constructor | |
| JAVA0274 | 0.00 | JAVA0274 Serializable class has a synchronized readObject() | |
| JAVA0275 | 0.00 | JAVA0275 Serializable class has a synchronized writeObject() and no other synchronized methods | |
| JAVA0276 | 0.00 | JAVA0276 Unnecessary use of String constructor | |
| JAVA0277 | 4.00 | JAVA0277 Iterator.next() implementation does not throw NoSuchElementException | |
| JAVA0278 | 0.00 | JAVA0278 Unnecessary use of Boolean constructor | |
| JAVA0279 | 0.00 | JAVA0279 Serialization method readObject or readObjectNoData calls an overridable method | |
| JAVA0280 | 0.00 | JAVA0280 IllegalMonitorStateException caught | |
| JAVA0281 | 0.00 | JAVA0281 Iterator.next() not called in loop | |
| JAVA0282 | 0.00 | JAVA0282 Call to Iterator.next() in loop which does not test Iterator.hasNext() | |
| JAVA0283 | 0.00 | JAVA0283 Control variable not updated in loop body | |
| JAVA0284 | 0.00 | JAVA0284 Explicit garbage collection | |
| JAVA0285 | 0.00 | JAVA0285 Dereference of potentially null variable | |
| JAVA0286 | 0.00 | JAVA0286 Dereference of null variable | |
| JAVA0287 | 0.00 | JAVA0287 Unnecessary null check | |
| JAVA0288 | 0.00 | JAVA0288 Inconsistent null check | |
| LINES | 979.00 | Number of lines in the source file | |
| LINE_COMMENT | 32.00 | Number of line comments | |
| LOC | 466.00 | Lines of code | |
| LOGICAL_LINES | 228.00 | Number of statements | |
| LOOPS | 10.00 | Number of loops | |
| NEST_DEPTH | 4.00 | Maximum nesting depth | |
| OPERANDS | 849.00 | Number of operands | |
| OPERATORS | 1914.00 | Number of operators | |
| PARAMS | 53.00 | Number of formal parameter declarations | |
| PROGRAM_LENGTH | 2763.00 | Halstead program length | |
| PROGRAM_VOCAB | 351.00 | Halstead program vocabulary | |
| PROGRAM_VOLUME | 0.00 | Halstead program volume | |
| RETURNS | 107.00 | Number of return points from functions | |
| SIZE | 32760.00 | Size of the file in bytes | |
| UNIQUE_OPERANDS | 295.00 | Number of unique operands | |
| UNIQUE_OPERATORS | 56.00 | Number of unique operators | |
| WHITESPACE | 96.00 | Number of whitespace lines | |