001    /*
002     * Created on Dec 23, 2007
003     *
004     * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
005     * in compliance with the License. You may obtain a copy of the License at
006     *
007     * http://www.apache.org/licenses/LICENSE-2.0
008     *
009     * Unless required by applicable law or agreed to in writing, software distributed under the License
010     * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
011     * or implied. See the License for the specific language governing permissions and limitations under
012     * the License.
013     *
014     * Copyright @2007-2010 the original author or authors.
015     */
016    package org.fest.swing.format;
017    
018    import static org.fest.util.Strings.concat;
019    
020    import java.awt.Component;
021    
022    /**
023     * Understands a template for implementations of <code>{@link ComponentFormatter}</code>.
024     *
025     * @author Yvonne Wang
026     */
027    public abstract class ComponentFormatterTemplate implements ComponentFormatter {
028    
029      /**
030       * Returns the <code>String</code> representation of the given <code>{@link Component}</code>.
031       * @param c the given <code>Component</code>.
032       * @return the <code>String</code> representation of the given <code>Component</code>.
033       * @throws NullPointerException if the given <code>Component</code> is <code>null</code>.
034       * @throws IllegalArgumentException if the type of the given <code>Component</code> is not supported by this 
035       * formatter. 
036       */
037      public final String format(Component c) {
038        validateTypeOf(c);
039        return doFormat(c);
040      }
041    
042      /**
043       * Returns the <code>String</code> representation of the given <code>{@link Component}</code>.
044       * @param c the given <code>Component</code>.
045       * @return the <code>String</code> representation of the given <code>Component</code>.
046       */
047      protected abstract String doFormat(Component c);
048    
049      private void validateTypeOf(Component c) {
050        if (c == null) throw new NullPointerException("The component should not be null");
051        if (!targetType().isAssignableFrom(c.getClass()))
052          throw new IllegalArgumentException(concat("This formatter only supports components of type ", targetType().getName()));
053      }
054    
055    
056    }