| // Copyright 2004 The Apache Software Foundation |
| // |
| // Licensed 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 org.apache.tapestry.contrib.table.model.simple; |
| |
| import java.util.Comparator; |
| |
| /** |
| * In order to provide more generic behaviour, ITableColumn |
| * has no "column value" concept. The comparator it returns |
| * compares two table rows, rather than values specific to the column. |
| * <p> |
| * SimpleTableColumn introduces the concept of "column value" and |
| * allows one to extract that "column value" from the row using |
| * the getColumnValue() method. In practice comparisons are also typically |
| * done between these values rather than the full row objects. |
| * <p> |
| * This comparator extracts the column values from the rows passed |
| * and uses the provided comparator to compare the values. |
| * It therefore allows a comparator designed for comparing column values to be |
| * quickly wrapped and used as a comparator comparing rows, which is what |
| * ITableColumn is expected to return. |
| * <p> |
| * Example: |
| * <p> |
| * objColumn.setComparator(new ColumnComparator(objColumn, objBeanComparator)); |
| * |
| * @version $Id$ |
| * @author mindbridge |
| * |
| */ |
| public class ColumnComparator implements Comparator |
| { |
| private SimpleTableColumn m_objColumn; |
| private Comparator m_objComparator; |
| |
| public ColumnComparator(SimpleTableColumn objColumn, Comparator objComparator) |
| { |
| m_objColumn = objColumn; |
| m_objComparator = objComparator; |
| } |
| |
| /** |
| * @see java.util.Comparator#compare(Object, Object) |
| */ |
| public int compare(Object objRow1, Object objRow2) |
| { |
| Object objValue1 = m_objColumn.getColumnValue(objRow1); |
| Object objValue2 = m_objColumn.getColumnValue(objRow2); |
| |
| return m_objComparator.compare(objValue1, objValue2); |
| } |
| |
| } |