Add negate(Boolean) method

git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/lang/trunk@137204 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/commons/lang/BooleanUtils.java

@@ -58,7 +58,7 @@ package org.apache.commons.lang;
  * boolean and Boolean objects.</p>
  *
  * @author Stephen Colebourne
- * @version $Id: BooleanUtils.java,v 1.1 2002/12/15 16:55:32 scolebourne Exp $
+ * @version $Id: BooleanUtils.java,v 1.2 2002/12/22 21:33:12 scolebourne Exp $
  */
 public class BooleanUtils {
 
@@ -72,6 +72,24 @@ public class BooleanUtils {
     public BooleanUtils() {
     }
 
+    // Boolean utilities
+    //--------------------------------------------------------------------------
+    
+    /**
+     * <p>Negates the specified boolean.</p>
+     * 
+     * <p>If <code>null</code> is passed in, <code>null</code> will be returned.</p>
+     * 
+     * @param bool  the Boolean to negate, may be null
+     * @return the negated Boolean, or <code>null</code> if <code>null</code> passed in
+     */
+    public static Boolean negate(Boolean bool) {
+        if (bool == null) {
+            return null;
+        }
+        return (bool.booleanValue() ? Boolean.FALSE : Boolean.TRUE);
+    }
+    
     // boolean Boolean methods
     //--------------------------------------------------------------------------
     

src/test/org/apache/commons/lang/BooleanUtilsTest.java

@@ -61,7 +61,7 @@ import junit.textui.TestRunner;
  * Unit tests {@link org.apache.commons.lang.BooleanUtils}.
  *
  * @author Stephen Colebourne
- * @version $Id: BooleanUtilsTest.java,v 1.1 2002/12/15 16:55:32 scolebourne Exp $
+ * @version $Id: BooleanUtilsTest.java,v 1.2 2002/12/22 21:33:12 scolebourne Exp $
  */
 public class BooleanUtilsTest extends TestCase {
 
@@ -87,6 +87,13 @@ public class BooleanUtilsTest extends TestCase {
         super.tearDown();
     }
 
+    //-----------------------------------------------------------------------
+    public void test_negate_Boolean() {
+        assertSame(null, BooleanUtils.negate(null));
+        assertSame(Boolean.TRUE, BooleanUtils.negate(Boolean.FALSE));
+        assertSame(Boolean.FALSE, BooleanUtils.negate(Boolean.TRUE));
+    }
+
     //-----------------------------------------------------------------------
     public void test_toBooleanObject_boolean() {
         assertSame(Boolean.TRUE, BooleanUtils.toBooleanObject(true));