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Java > Open Source Codes > org > odmg > DCollection


1 package org.odmg;
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7 /**
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9  * The base interface for all ODMG collections.
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11  * The ODMG collections are based on JavaSoft’s collection interfaces.
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13  * All of the operations defined by the JavaSoft <code>Collection</code>
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15  * interface are supported by an ODMG implementation of <code>DCollection</code>;
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17  * the exception <code>UnsupportedOperationException</code> is not thrown when a
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19  * call is made to any of the <code>Collection</code> methods.
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21  * <p>
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23  * <code>DCollection</code> contains methods used to perform queries on the collection.
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25  * The OQL query predicate is given as a string with the syntax of the
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27  * <code>where</code> clause of OQL. The predefined OQL variable <code>this</code>
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29  * is used inside the predicate to denote the current element of the collection.
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31  * @author David Jordan (as Java Editor of the Object Data Management Group)
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33  * @version ODMG 3.0
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35  */
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37 // * @see com.sun.java.util.collections.UnsupportedOperationException
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41 public interface DCollection extends java.util.Collection JavaDoc
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43 {
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45     /**
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47      * Selects the single element of the collection for which the provided OQL query
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49      * predicate is true.
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51      * @param predicate An OQL boolean query predicate.
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53      * @return The element that evaluates to true for the predicate. If no element
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55      * evaluates to true, null is returned.
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57      * @exception QueryInvalidException The query predicate is invalid.
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59      */
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61     public Object JavaDoc selectElement(String JavaDoc predicate) throws QueryInvalidException;
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65     /**
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67      * Access all of the elements of the collection that evaluate to true for the
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69      * provided query predicate.
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71      * @param predicate An OQL boolean query predicate.
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73      * @return An iterator used to iterate over the elements that evaluated true for the predicate.
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75      * @exception QueryInvalidException The query predicate is invalid.
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77      */
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79     public java.util.Iterator JavaDoc select(String JavaDoc predicate) throws QueryInvalidException;
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83     /**
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85      * Evaluate the boolean query predicate for each element of the collection and
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87      * return a new collection that contains each element that evaluated to true.
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89      * @param predicate An OQL boolean query predicate.
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91      * @return A new collection containing the elements that evaluated true for the predicate.
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93      * @exception QueryInvalidException The query predicate is invalid.
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95      */
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97     public DCollection query(String JavaDoc predicate) throws QueryInvalidException;
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101     /**
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103      * Determines whether there is an element of the collection that evaluates to true
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105      * for the predicate.
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107      * @param predicate An OQL boolean query predicate.
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109      * @return True if there is an element of the collection that evaluates to true
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111      * for the predicate, otherwise false.
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113      * @exception QueryInvalidException The query predicate is invalid.
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115      */
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117     public boolean existsElement(String JavaDoc predicate) throws QueryInvalidException;
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119 }
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