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Add StringValue transformer 

from  James Carman


git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/collections/trunk@131160 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Stephen Colebourne 2003-09-17 20:28:30 +00:00
parent e41abcddc6
commit c3992caf1d
2 changed files with 55 additions and 5 deletions
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41
src/java/org/apache/commons/collections/TransformerUtils.java
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@ -1,5 +1,5 @@
/* /*
* $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//collections/src/java/org/apache/commons/collections/TransformerUtils.java,v 1.3 2003/08/31 17:26:44 scolebourne Exp $ * $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//collections/src/java/org/apache/commons/collections/TransformerUtils.java,v 1.4 2003/09/17 20:28:30 scolebourne Exp $
* ==================================================================== * ====================================================================
* *
* The Apache Software License, Version 1.1 * The Apache Software License, Version 1.1
@ -82,13 +82,15 @@ import java.util.Map;
* <li>Null - always returns null * <li>Null - always returns null
* <li>NOP - returns the input object, which should be immutable * <li>NOP - returns the input object, which should be immutable
* <li>Exception - always throws an exception * <li>Exception - always throws an exception
* <li>StringValue - returns a <code>java.lang.String</code> representation of the input object
* </ul> * </ul>
* All the supplied transformers are Serializable. * All the supplied transformers are Serializable.
* *
* @since Commons Collections 3.0 * @since Commons Collections 3.0
* @version $Revision: 1.3 $ $Date: 2003/08/31 17:26:44 $ * @version $Revision: 1.4 $ $Date: 2003/09/17 20:28:30 $
* *
* @author Stephen Colebourne * @author Stephen Colebourne
* @author James Carman
*/ */
public class TransformerUtils { public class TransformerUtils {
@ -113,6 +115,12 @@ public class TransformerUtils {
*/ */
private static final Transformer INSTANTIATE_TRANSFORMER = new InstantiateTransformer(null, null); private static final Transformer INSTANTIATE_TRANSFORMER = new InstantiateTransformer(null, null);
/**
* A transformer that returns a <code>java.lang.String</code> representation
* of the input object.
*/
private static final Transformer STRING_VALUE_TRANSFORMER = new StringValueTransformer();
/** /**
* This class is not normally instantiated. * This class is not normally instantiated.
*/ */
@ -490,6 +498,17 @@ public class TransformerUtils {
return new InvokerTransformer(methodName, paramTypes, args); return new InvokerTransformer(methodName, paramTypes, args);
} }
/**
* Gets a transformer that returns a <code>java.lang.String</code>
* representation of the input object. This is achieved via the
* <code>toString</code> method, <code>null</code> returns 'null'.
*
* @return the transformer
*/
public static Transformer stringValueTransformer() {
return STRING_VALUE_TRANSFORMER;
}
/** /**
* Copy method * Copy method
* *
@ -935,4 +954,22 @@ public class TransformerUtils {
} }
} }
// StringValueTransformer
//----------------------------------------------------------------------------------
/**
* StringValueTransformer returns a <code>java.lang.String</code> representation
* of the input object using the <code>String.valueOf()</code> method.
*/
private static class StringValueTransformer implements Transformer, Serializable {
/**
* returns a <code>java.lang.String</code> representation of the input object
* using the <code>String.valueOf()</code> method.
*/
public Object transform(Object input) {
return String.valueOf(input);
}
}
} }

17
src/test/org/apache/commons/collections/TestTransformerUtils.java
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@ -1,5 +1,5 @@
/* /*
* $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//collections/src/test/org/apache/commons/collections/TestTransformerUtils.java,v 1.2 2003/08/31 17:28:43 scolebourne Exp $ * $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//collections/src/test/org/apache/commons/collections/TestTransformerUtils.java,v 1.3 2003/09/17 20:28:30 scolebourne Exp $
* ==================================================================== * ====================================================================
* *
* The Apache Software License, Version 1.1 * The Apache Software License, Version 1.1
@ -72,9 +72,10 @@ import junit.textui.TestRunner;
* Tests the org.apache.commons.collections.TransformerUtils class. * Tests the org.apache.commons.collections.TransformerUtils class.
* *
* @since Commons Collections 3.0 * @since Commons Collections 3.0
* @version $Revision: 1.2 $ $Date: 2003/08/31 17:28:43 $ * @version $Revision: 1.3 $ $Date: 2003/09/17 20:28:30 $
* *
* @author Stephen Colebourne * @author Stephen Colebourne
* @author James Carman
*/ */
public class TestTransformerUtils extends junit.framework.TestCase { public class TestTransformerUtils extends junit.framework.TestCase {
@ -535,4 +536,16 @@ public class TestTransformerUtils extends junit.framework.TestCase {
fail(); fail();
} }
// stringValueTransformer
//------------------------------------------------------------------
public void testStringValueTransformer() {
assertNotNull( "StringValueTransformer should NEVER return a null value.",
TransformerUtils.stringValueTransformer().transform(null));
assertEquals( "StringValueTransformer should return \"null\" when given a null argument.", "null",
TransformerUtils.stringValueTransformer().transform(null));
assertEquals( "StringValueTransformer should return toString value", "6",
TransformerUtils.stringValueTransformer().transform(new Integer(6)));
}
} }