LMS-257 new method (with test): ClassUtils.gatherAllCastableClassesAndInterfacesFor

SVN: 4768

common/source/java/ch/systemsx/cisd/common/utilities/ClassUtils.java

@@ -21,6 +21,9 @@ import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.util.Arrays;
+import java.util.Collection;
+import java.util.LinkedHashSet;
+import java.util.Set;
 
 import org.apache.commons.lang.StringUtils;
 
@@ -37,6 +40,33 @@ public final class ClassUtils
     {
         // Can not be instantiated.
     }
+    
+    /**
+     * Gathers all classes and interfaces the specified object can be casted to.
+     */
+    public static Collection<Class<?>> gatherAllCastableClassesAndInterfacesFor(Object object)
+    {
+        assert object != null;
+        
+        Set<Class<?>> classes = new LinkedHashSet<Class<?>>();
+        gather(classes, object.getClass());
+        return classes;
+    }
+
+    private static void gather(Set<Class<?>> classes, Class<?> clazz)
+    {
+        classes.add(clazz);
+        Class<?> superclass = clazz.getSuperclass();
+        if (superclass != null)
+        {
+            gather(classes, superclass);
+        }
+        Class<?>[] interfaces = clazz.getInterfaces();
+        for (Class<?> interfaze : interfaces)
+        {
+            gather(classes, interfaze);
+        }
+    }
 
     /**
      * Returns the currently called <code>Method</code>.

common/sourceTest/java/ch/systemsx/cisd/common/utilities/ClassUtilsTest.java

@@ -26,6 +26,8 @@ import static org.testng.AssertJUnit.fail;
 
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Properties;
 
@@ -38,6 +40,29 @@ import org.testng.annotations.Test;
  */
 public final class ClassUtilsTest
 {
+    private static interface IA {}
+    private static interface IExtendingIA extends IA {}
+    private static interface IB {}
+    private static class A {} 
+    private static class ExtendingA extends A implements IExtendingIA {}
+    private static class ExtendingExtendingA extends ExtendingA implements IB, IA {}
+    
+    @Test
+    public void testGatherAllCastableClassesAndInterfacesFor()
+    {
+        ExtendingExtendingA object = new ExtendingExtendingA();
+        Collection<Class<?>> classes = ClassUtils.gatherAllCastableClassesAndInterfacesFor(object);
+        Iterator<Class<?>> iterator = classes.iterator();
+        assertSame(ExtendingExtendingA.class, iterator.next());
+        assertSame(ExtendingA.class, iterator.next());
+        assertSame(A.class, iterator.next());
+        assertSame(Object.class, iterator.next());
+        assertSame(IExtendingIA.class, iterator.next());
+        assertSame(IA.class, iterator.next());
+        assertSame(IB.class, iterator.next());
+        
+        assertEquals(false, iterator.hasNext());
+    }
 
     /**
      * Test method for {@link ch.systemsx.cisd.common.utilities.ClassUtils#getCurrentMethod()}.