Java tutorial
/* * Copyright (c) 2000, 2014, 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 javax.management.openmbean; // java import // import java.util.Set; import java.util.TreeMap; import java.util.Collections; import java.util.Iterator; // jmx import // /** * The <code>CompositeType</code> class is the <i>open type</i> class * whose instances describe the types of {@link CompositeData CompositeData} values. * * * @since 1.5 */ public class CompositeType extends OpenType<CompositeData> { /* Serial version */ static final long serialVersionUID = -5366242454346948798L; /** * @serial Sorted mapping of the item names to their descriptions */ private TreeMap<String, String> nameToDescription; /** * @serial Sorted mapping of the item names to their open types */ private TreeMap<String, OpenType<?>> nameToType; /* As this instance is immutable, following three values need only * be calculated once. */ private transient Integer myHashCode = null; private transient String myToString = null; private transient Set<String> myNamesSet = null; /* *** Constructor *** */ /** * Constructs a <code>CompositeType</code> instance, checking for the validity of the given parameters. * The validity constraints are described below for each parameter. * <p> * Note that the contents of the three array parameters * <var>itemNames</var>, <var>itemDescriptions</var> and <var>itemTypes</var> * are internally copied so that any subsequent modification of these arrays by the caller of this constructor * has no impact on the constructed <code>CompositeType</code> instance. * <p> * The Java class name of composite data values this composite type represents * (ie the class name returned by the {@link OpenType#getClassName() getClassName} method) * is set to the string value returned by <code>CompositeData.class.getName()</code>. * * @param typeName The name given to the composite type this instance represents; cannot be a null or empty string. * * @param description The human readable description of the composite type this instance represents; * cannot be a null or empty string. * * @param itemNames The names of the items contained in the * composite data values described by this <code>CompositeType</code> instance; * cannot be null and should contain at least one element; no element can be a null or empty string. * Note that the order in which the item names are given is not important to differentiate a * <code>CompositeType</code> instance from another; * the item names are internally stored sorted in ascending alphanumeric order. * * @param itemDescriptions The descriptions, in the same order as <var>itemNames</var>, of the items contained in the * composite data values described by this <code>CompositeType</code> instance; * should be of the same size as <var>itemNames</var>; * no element can be null or an empty string. * * @param itemTypes The open type instances, in the same order as <var>itemNames</var>, describing the items contained * in the composite data values described by this <code>CompositeType</code> instance; * should be of the same size as <var>itemNames</var>; * no element can be null. * * @throws IllegalArgumentException If <var>typeName</var> or <var>description</var> is a null or empty string, * or <var>itemNames</var> or <var>itemDescriptions</var> or <var>itemTypes</var> is null, * or any element of <var>itemNames</var> or <var>itemDescriptions</var> * is a null or empty string, * or any element of <var>itemTypes</var> is null, * or <var>itemNames</var> or <var>itemDescriptions</var> or <var>itemTypes</var> * are not of the same size. * * @throws OpenDataException If <var>itemNames</var> contains duplicate item names * (case sensitive, but leading and trailing whitespaces removed). */ public CompositeType(String typeName, String description, String[] itemNames, String[] itemDescriptions, OpenType<?>[] itemTypes) throws OpenDataException { // Check and construct state defined by parent // super(CompositeData.class.getName(), typeName, description, false); // Check the 3 arrays are not null or empty (ie length==0) and that there is no null element or empty string in them // checkForNullElement(itemNames, "itemNames"); checkForNullElement(itemDescriptions, "itemDescriptions"); checkForNullElement(itemTypes, "itemTypes"); checkForEmptyString(itemNames, "itemNames"); checkForEmptyString(itemDescriptions, "itemDescriptions"); // Check the sizes of the 3 arrays are the same // if ((itemNames.length != itemDescriptions.length) || (itemNames.length != itemTypes.length)) { throw new IllegalArgumentException("Array arguments itemNames[], itemDescriptions[] and itemTypes[] " + "should be of same length (got " + itemNames.length + ", " + itemDescriptions.length + " and " + itemTypes.length + ")."); } // Initialize internal "names to descriptions" and "names to types" sorted maps, // and, by doing so, check there are no duplicate item names // nameToDescription = new TreeMap<String, String>(); nameToType = new TreeMap<String, OpenType<?>>(); String key; for (int i = 0; i < itemNames.length; i++) { key = itemNames[i].trim(); if (nameToDescription.containsKey(key)) { throw new OpenDataException("Argument's element itemNames[" + i + "]=\"" + itemNames[i] + "\" duplicates a previous item names."); } nameToDescription.put(key, itemDescriptions[i].trim()); nameToType.put(key, itemTypes[i]); } } private static void checkForNullElement(Object[] arg, String argName) { if ((arg == null) || (arg.length == 0)) { throw new IllegalArgumentException("Argument " + argName + "[] cannot be null or empty."); } for (int i = 0; i < arg.length; i++) { if (arg[i] == null) { throw new IllegalArgumentException("Argument's element " + argName + "[" + i + "] cannot be null."); } } } private static void checkForEmptyString(String[] arg, String argName) { for (int i = 0; i < arg.length; i++) { if (arg[i].trim().isEmpty()) { throw new IllegalArgumentException( "Argument's element " + argName + "[" + i + "] cannot be an empty string."); } } } /* *** Composite type specific information methods *** */ /** * Returns <code>true</code> if this <code>CompositeType</code> instance defines an item * whose name is <var>itemName</var>. * * @param itemName the name of the item. * * @return true if an item of this name is present. */ public boolean containsKey(String itemName) { if (itemName == null) { return false; } return nameToDescription.containsKey(itemName); } /** * Returns the description of the item whose name is <var>itemName</var>, * or <code>null</code> if this <code>CompositeType</code> instance does not define any item * whose name is <var>itemName</var>. * * @param itemName the name of the item. * * @return the description. */ public String getDescription(String itemName) { if (itemName == null) { return null; } return nameToDescription.get(itemName); } /** * Returns the <i>open type</i> of the item whose name is <var>itemName</var>, * or <code>null</code> if this <code>CompositeType</code> instance does not define any item * whose name is <var>itemName</var>. * * @param itemName the name of the time. * * @return the type. */ public OpenType<?> getType(String itemName) { if (itemName == null) { return null; } return (OpenType<?>) nameToType.get(itemName); } /** * Returns an unmodifiable Set view of all the item names defined by this <code>CompositeType</code> instance. * The set's iterator will return the item names in ascending order. * * @return a {@link Set} of {@link String}. */ public Set<String> keySet() { // Initializes myNamesSet on first call if (myNamesSet == null) { myNamesSet = Collections.unmodifiableSet(nameToDescription.keySet()); } return myNamesSet; // always return the same value } /** * Tests whether <var>obj</var> is a value which could be * described by this <code>CompositeType</code> instance. * * <p>If <var>obj</var> is null or is not an instance of * <code>javax.management.openmbean.CompositeData</code>, * <code>isValue</code> returns <code>false</code>.</p> * * <p>If <var>obj</var> is an instance of * <code>javax.management.openmbean.CompositeData</code>, then let * {@code ct} be its {@code CompositeType} as returned by {@link * CompositeData#getCompositeType()}. The result is true if * {@code this} is <em>assignable from</em> {@code ct}. This * means that:</p> * * <ul> * <li>{@link #getTypeName() this.getTypeName()} equals * {@code ct.getTypeName()}, and * <li>there are no item names present in {@code this} that are * not also present in {@code ct}, and * <li>for every item in {@code this}, its type is assignable from * the type of the corresponding item in {@code ct}. * </ul> * * <p>A {@code TabularType} is assignable from another {@code * TabularType} if they have the same {@linkplain * TabularType#getTypeName() typeName} and {@linkplain * TabularType#getIndexNames() index name list}, and the * {@linkplain TabularType#getRowType() row type} of the first is * assignable from the row type of the second. * * <p>An {@code ArrayType} is assignable from another {@code * ArrayType} if they have the same {@linkplain * ArrayType#getDimension() dimension}; and both are {@linkplain * ArrayType#isPrimitiveArray() primitive arrays} or neither is; * and the {@linkplain ArrayType#getElementOpenType() element * type} of the first is assignable from the element type of the * second. * * <p>In every other case, an {@code OpenType} is assignable from * another {@code OpenType} only if they are equal.</p> * * <p>These rules mean that extra items can be added to a {@code * CompositeData} without making it invalid for a {@code CompositeType} * that does not have those items.</p> * * @param obj the value whose open type is to be tested for compatibility * with this <code>CompositeType</code> instance. * * @return <code>true</code> if <var>obj</var> is a value for this * composite type, <code>false</code> otherwise. */ public boolean isValue(Object obj) { // if obj is null or not CompositeData, return false // if (!(obj instanceof CompositeData)) { return false; } // if obj is not a CompositeData, return false // CompositeData value = (CompositeData) obj; // test value's CompositeType is assignable to this CompositeType instance // CompositeType valueType = value.getCompositeType(); return this.isAssignableFrom(valueType); } /** * Tests whether values of the given type can be assigned to this * open type. The result is true if the given type is also a * CompositeType with the same name ({@link #getTypeName()}), and * every item in this type is also present in the given type with * the same name and assignable type. There can be additional * items in the given type, which are ignored. * * @param ot the type to be tested. * * @return true if {@code ot} is assignable to this open type. */ @Override boolean isAssignableFrom(OpenType<?> ot) { if (!(ot instanceof CompositeType)) return false; CompositeType ct = (CompositeType) ot; if (!ct.getTypeName().equals(getTypeName())) return false; for (String key : keySet()) { OpenType<?> otItemType = ct.getType(key); OpenType<?> thisItemType = getType(key); if (otItemType == null || !thisItemType.isAssignableFrom(otItemType)) return false; } return true; } /* *** Methods overriden from class Object *** */ /** * Compares the specified <code>obj</code> parameter with this <code>CompositeType</code> instance for equality. * <p> * Two <code>CompositeType</code> instances are equal if and only if all of the following statements are true: * <ul> * <li>their type names are equal</li> * <li>their items' names and types are equal</li> * </ul> * * @param obj the object to be compared for equality with this <code>CompositeType</code> instance; * if <var>obj</var> is <code>null</code>, <code>equals</code> returns <code>false</code>. * * @return <code>true</code> if the specified object is equal to this <code>CompositeType</code> instance. */ public boolean equals(Object obj) { // if obj is null, return false // if (obj == null) { return false; } // if obj is not a CompositeType, return false // CompositeType other; try { other = (CompositeType) obj; } catch (ClassCastException e) { return false; } // Now, really test for equality between this CompositeType instance and the other // // their names should be equal if (!this.getTypeName().equals(other.getTypeName())) { return false; } // their items names and types should be equal if (!this.nameToType.equals(other.nameToType)) { return false; } // All tests for equality were successfull // return true; } /** * Returns the hash code value for this <code>CompositeType</code> instance. * <p> * The hash code of a <code>CompositeType</code> instance is the sum of the hash codes * of all elements of information used in <code>equals</code> comparisons * (ie: name, items names, items types). * This ensures that <code> t1.equals(t2) </code> implies that <code> t1.hashCode()==t2.hashCode() </code> * for any two <code>CompositeType</code> instances <code>t1</code> and <code>t2</code>, * as required by the general contract of the method * {@link Object#hashCode() Object.hashCode()}. * <p> * As <code>CompositeType</code> instances are immutable, the hash code for this instance is calculated once, * on the first call to <code>hashCode</code>, and then the same value is returned for subsequent calls. * * @return the hash code value for this <code>CompositeType</code> instance */ public int hashCode() { // Calculate the hash code value if it has not yet been done (ie 1st call to hashCode()) // if (myHashCode == null) { int value = 0; value += this.getTypeName().hashCode(); for (String key : nameToDescription.keySet()) { value += key.hashCode(); value += this.nameToType.get(key).hashCode(); } myHashCode = Integer.valueOf(value); } // return always the same hash code for this instance (immutable) // return myHashCode.intValue(); } /** * Returns a string representation of this <code>CompositeType</code> instance. * <p> * The string representation consists of * the name of this class (ie <code>javax.management.openmbean.CompositeType</code>), the type name for this instance, * and the list of the items names and types string representation of this instance. * <p> * As <code>CompositeType</code> instances are immutable, the string representation for this instance is calculated once, * on the first call to <code>toString</code>, and then the same value is returned for subsequent calls. * * @return a string representation of this <code>CompositeType</code> instance */ public String toString() { // Calculate the string representation if it has not yet been done (ie 1st call to toString()) // if (myToString == null) { final StringBuilder result = new StringBuilder(); result.append(this.getClass().getName()); result.append("(name="); result.append(getTypeName()); result.append(",items=("); int i = 0; Iterator<String> k = nameToType.keySet().iterator(); String key; while (k.hasNext()) { key = k.next(); if (i > 0) result.append(","); result.append("(itemName="); result.append(key); result.append(",itemType="); result.append(nameToType.get(key).toString() + ")"); i++; } result.append("))"); myToString = result.toString(); } // return always the same string representation for this instance (immutable) // return myToString; } }