DataField


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64  
65  package com.jcorporate.expresso.core.dataobjects;
66  
67  import java.io.InputStream  ;
68  import java.math.BigDecimal  ;
69  import java.util.Date  ;
70  import java.util.Map  ;
71  
72  /**
73   * This class represents a single field of data that is stored within the
74   * data object.  It will provide basic manipulations such as it's original
75   * value, and attribute holdings.
76   *
77   * @author Michael Rimov
78   * @since Expresso 5.0.1
79   */
80  
81  public interface DataField {
82  
83      /**
84       * Retrieves the wrapped object for the Data Field
85       *
86       * @return java.lang.Object or null
87       */
88      public Object   getValue();
89  
90      /**
91       * Retrieves the wrapped object as a String
92       *
93       * @return java.lang.String
94       */
95      public String   asString();
96  
97  
98      /**
99       * Retrieve the boolean object value.
100      *
101      * @return java.lang.Boolean
102      */
103     public Boolean   asBoolean();
104 
105     /**
106      * Retrieves the wrapped object as an <code>Integer</code> or zero if it's an invalid format.
107      *
108      * @return a java.lang.Integer object, or null if the object is null.
109      */
110     public Integer   asInteger();
111 
112     /**
113      * Retrieve the wrapped object as a <code>Date</code> object or possibly null if we
114      * can't convert it or the object is null.
115      *
116      * @return a properly instantiated <code>Date</code> Object if we're able to convert it.
117      */
118     public Date   asDate();
119 
120     /**
121      * Retrieve the wrapped object as a <code>BigDecimal</code> object or zero if we're unable
122      * to convert it.
123      *
124      * @return a properly instantiated <code>BigDecimal</code> Object if we're able to convert it.
125      */
126     public BigDecimal   asBigDecimal();
127 
128     /**
129      * Retrieve the wrapped object as a <code>Double</code> object or zero if we
130      * can't convert i
131      *
132      * @return a properly instantiated <code>Double</code> Object if we're able to convert it.
133      */
134     public Double   asDouble();
135 
136     /**
137      * @return the original object or null
138      * @deprecated 8/04 v.5.5 do not expose this cache
139      *             Retrieve the last original value if the data has changed.  Will return
140      *             null if isChanged() is false
141      */
142     public Object   getOriginalValue();
143 
144 
145     /**
146      * Allows for retrieval of BLOB database types.
147      *
148      * @return java.io.InputStream
149      */
150     public InputStream   asStream();
151 
152     /**
153      * Used for change logging.
154      *
155      * @return true if the field has changed since the last reset
156      */
157     public boolean isChanged();
158 
159     /**
160      * Used for change logging.
161      *
162      * @return true if the field has been set since the last reset
163      */
164     public boolean isValueSet();
165 
166     /**
167      * Make sure the value of the field is valid.
168      *
169      * @throws DataException if the field value is not valid
170      */
171     public void checkValue() throws DataException;
172 
173     /**
174      * Resets the changed flag and sets the original value field to null
175      */
176     public void resetChanged();
177 
178     /**
179      * Sets the wrapped object for the data field
180      *
181      * @param newValue a new Object to set the value to
182      */
183     public void setValue(Object   newValue);
184 
185     /**
186      * Returns true if the object is null.
187      *
188      * @return true if the object is null
189      */
190     public boolean isNull();
191 
192     /**
193      * Sets an attribute for this particular instance of the Data field
194      *
195      * @param attributeName the name of the attribute to set
196      * @param value         the value to set it to
197      */
198     public void setAttribute(String   attributeName, Object   value);
199 
200     /**
201      * Retrieves any user defined attributes for this field.
202      *
203      * @param attributeName the name of the attribute to retrieve
204      * @return an object or null if the attribute doesn't exist
205      */
206     public Object   getAttribute(String   attributeName);
207 
208 
209     /**
210      * Returns a Read Only <code>Map</code> of all attributes in name-value pairs.  If there are no
211      * attributes then getAllAttributes will return a null map.
212      *
213      * @return java.util.map
214      */
215     public Map   getAllAttributes();
216 
217     /**
218      * Returns a handle to the DataObject that is the container for this
219      * Data Field
220      *
221      * @return DataObject the containing data object.
222      */
223     public DataObject getOwner();
224 
225     /**
226      * Sets the owner of a given DataObject
227      *
228      * @param newOwner The new parent object.
229      */
230     public void setOwner(DataObject newOwner);
231 
232 
233     /**
234      * Returns a handle to the Field MetaData object.
235      *
236      * @return DataFieldMetaData
237      */
238     public DataFieldMetaData getFieldMetaData();
239 
240     /**
241      * Sets the metadata object for this field.
242      *
243      * @param newMetadata the new Field Meta data object... for example <code>DBField</code>
244      */
245     public void setFieldMetaData(DataFieldMetaData newMetadata);
246 
247     /**
248      * call after add() or update(). The currentValue of data fields should be considered the baseline, the 'original value' for purposes of determining 'isChanged'
249      */
250     public void cacheIsChangedComparison();
251 }
252
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