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.ArrayList; import java.util.Collections; import java.util.Iterator; import java.util.List; // jmx import // /** * The <code>TabularType</code> class is the <i> open type</i> class * whose instances describe the types of {@link TabularData TabularData} values. * * @since 1.5 */ public class TabularType extends OpenType<TabularData> { /* Serial version */ static final long serialVersionUID = 6554071860220659261L; /** * @serial The composite type of rows */ private CompositeType rowType; /** * @serial The items used to index each row element, kept in the order the user gave * This is an unmodifiable {@link ArrayList} */ private List<String> indexNames; private transient Integer myHashCode = null; // As this instance is immutable, these two values private transient String myToString = null; // need only be calculated once. /* *** Constructor *** */ /** * Constructs a <code>TabularType</code> instance, checking for the validity of the given parameters. * The validity constraints are described below for each parameter. * <p> * The Java class name of tabular data values this tabular type represents * (ie the class name returned by the {@link OpenType#getClassName() getClassName} method) * is set to the string value returned by <code>TabularData.class.getName()</code>. * * @param typeName The name given to the tabular type this instance represents; cannot be a null or empty string. * <br> * @param description The human readable description of the tabular type this instance represents; * cannot be a null or empty string. * <br> * @param rowType The type of the row elements of tabular data values described by this tabular type instance; * cannot be null. * <br> * @param indexNames The names of the items the values of which are used to uniquely index each row element in the * tabular data values described by this tabular type instance; * cannot be null or empty. Each element should be an item name defined in <var>rowType</var> * (no null or empty string allowed). * It is important to note that the <b>order</b> of the item names in <var>indexNames</var> * is used by the methods {@link TabularData#get(java.lang.Object[]) get} and * {@link TabularData#remove(java.lang.Object[]) remove} of class * <code>TabularData</code> to match their array of values parameter to items. * <br> * @throws IllegalArgumentException if <var>rowType</var> is null, * or <var>indexNames</var> is a null or empty array, * or an element in <var>indexNames</var> is a null or empty string, * or <var>typeName</var> or <var>description</var> is a null or empty string. * <br> * @throws OpenDataException if an element's value of <var>indexNames</var> * is not an item name defined in <var>rowType</var>. */ public TabularType(String typeName, String description, CompositeType rowType, String[] indexNames) throws OpenDataException { // Check and initialize state defined by parent. // super(TabularData.class.getName(), typeName, description, false); // Check rowType is not null // if (rowType == null) { throw new IllegalArgumentException("Argument rowType cannot be null."); } // Check indexNames is neither null nor empty and does not contain any null element or empty string // checkForNullElement(indexNames, "indexNames"); checkForEmptyString(indexNames, "indexNames"); // Check all indexNames values are valid item names for rowType // for (int i = 0; i < indexNames.length; i++) { if (!rowType.containsKey(indexNames[i])) { throw new OpenDataException("Argument's element value indexNames[" + i + "]=\"" + indexNames[i] + "\" is not a valid item name for rowType."); } } // initialize rowType // this.rowType = rowType; // initialize indexNames (copy content so that subsequent // modifs to the array referenced by the indexNames parameter // have no impact) // List<String> tmpList = new ArrayList<String>(indexNames.length + 1); for (int i = 0; i < indexNames.length; i++) { tmpList.add(indexNames[i]); } this.indexNames = Collections.unmodifiableList(tmpList); } /** * Checks that Object[] arg is neither null nor empty (ie length==0) * and that it does not contain any null element. */ 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."); } } } /** * Checks that String[] does not contain any empty (or blank characters only) string. */ 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."); } } } /* *** Tabular type specific information methods *** */ /** * Returns the type of the row elements of tabular data values * described by this <code>TabularType</code> instance. * * @return the type of each row. */ public CompositeType getRowType() { return rowType; } /** * <p>Returns, in the same order as was given to this instance's * constructor, an unmodifiable List of the names of the items the * values of which are used to uniquely index each row element of * tabular data values described by this <code>TabularType</code> * instance.</p> * * @return a List of String representing the names of the index * items. * */ public List<String> getIndexNames() { return indexNames; } /** * Tests whether <var>obj</var> is a value which could be * described by this <code>TabularType</code> instance. * * <p>If <var>obj</var> is null or is not an instance of * <code>javax.management.openmbean.TabularData</code>, * <code>isValue</code> returns <code>false</code>.</p> * * <p>If <var>obj</var> is an instance of * <code>javax.management.openmbean.TabularData</code>, say {@code * td}, the result is true if this {@code TabularType} is * <em>assignable from</em> {@link TabularData#getTabularType() * td.getTabularType()}, as defined in {@link * CompositeType#isValue CompositeType.isValue}.</p> * * @param obj the value whose open type is to be tested for * compatibility with this <code>TabularType</code> instance. * * @return <code>true</code> if <var>obj</var> is a value for this * tabular type, <code>false</code> otherwise. */ public boolean isValue(Object obj) { // if obj is null or not a TabularData, return false // if (!(obj instanceof TabularData)) return false; // if obj is not a TabularData, return false // TabularData value = (TabularData) obj; TabularType valueType = value.getTabularType(); return isAssignableFrom(valueType); } @Override boolean isAssignableFrom(OpenType<?> ot) { if (!(ot instanceof TabularType)) return false; TabularType tt = (TabularType) ot; if (!getTypeName().equals(tt.getTypeName()) || !getIndexNames().equals(tt.getIndexNames())) return false; return getRowType().isAssignableFrom(tt.getRowType()); } /* *** Methods overriden from class Object *** */ /** * Compares the specified <code>obj</code> parameter with this <code>TabularType</code> instance for equality. * <p> * Two <code>TabularType</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 row types are equal</li> * <li>they use the same index names, in the same order</li> * </ul> * <br> * @param obj the object to be compared for equality with this <code>TabularType</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>TabularType</code> instance. */ public boolean equals(Object obj) { // if obj is null, return false // if (obj == null) { return false; } // if obj is not a TabularType, return false // TabularType other; try { other = (TabularType) obj; } catch (ClassCastException e) { return false; } // Now, really test for equality between this TabularType instance and the other: // // their names should be equal if (!this.getTypeName().equals(other.getTypeName())) { return false; } // their row types should be equal if (!this.rowType.equals(other.rowType)) { return false; } // their index names should be equal and in the same order (ensured by List.equals()) if (!this.indexNames.equals(other.indexNames)) { return false; } // All tests for equality were successfull // return true; } /** * Returns the hash code value for this <code>TabularType</code> instance. * <p> * The hash code of a <code>TabularType</code> instance is the sum of the hash codes * of all elements of information used in <code>equals</code> comparisons * (ie: name, row type, index names). * This ensures that <code> t1.equals(t2) </code> implies that <code> t1.hashCode()==t2.hashCode() </code> * for any two <code>TabularType</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>TabularType</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>TabularType</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(); value += this.rowType.hashCode(); for (String index : indexNames) value += index.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>TabularType</code> instance. * <p> * The string representation consists of the name of this class (ie <code>javax.management.openmbean.TabularType</code>), * the type name for this instance, the row type string representation of this instance, * and the index names of this instance. * <p> * As <code>TabularType</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>TabularType</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().append(this.getClass().getName()).append("(name=") .append(getTypeName()).append(",rowType=").append(rowType.toString()).append(",indexNames=("); String sep = ""; for (String index : indexNames) { result.append(sep).append(index); sep = ","; } result.append("))"); myToString = result.toString(); } // return always the same string representation for this instance (immutable) // return myToString; } }