javadoc and polishing

org.springframework.core/src/main/java/org/springframework/core/convert/AbstractDescriptor.java

@@ -24,9 +24,9 @@ abstract class AbstractDescriptor {
 	private final Class<?> type;
 
 	public AbstractDescriptor(Class<?> type) {
-		//if (type == null) {
-	//		throw new IllegalArgumentException("type cannot be null");
-		//}
+		if (type == null) {
+			throw new IllegalArgumentException("type cannot be null");
+		}
 		this.type = type;
 	}
 	
@@ -68,11 +68,13 @@ abstract class AbstractDescriptor {
 
 	public AbstractDescriptor nested() {
 		if (isCollection()) {
-			return nested(resolveCollectionElementType(), 0);
+			Class<?> elementType = resolveCollectionElementType();
+			return elementType != null ? nested(elementType, 0) : null;
 		} else if (isArray()) {
 			return nested(getType().getComponentType(), 0);
 		} else if (isMap()) {
-			return nested(resolveMapValueType(), 1);
+			Class<?> mapValueType = resolveMapValueType();
+			return mapValueType != null ? nested(mapValueType, 1) : null;
 		} else {
 			throw new IllegalStateException("Not a collection, array, or map: cannot resolve nested value types");
 		}

org.springframework.core/src/main/java/org/springframework/core/convert/TypeDescriptor.java

@@ -316,9 +316,15 @@ public class TypeDescriptor {
 	}
 
 	/**
-	 * Creates a elementType descriptor from the provided collection or array element.
+	 * If this type is a {@link Collection} or an Array, creates a elementType descriptor from the provided collection or array element.
+	 * Narrows the {@link #getElementType() elementType} property to the class of the provided collection or array element.
+	 * For example, if this describes a java.util.List<java.lang.Number< and the element argument is a java.lang.Integer, the returned TypeDescriptor will be java.lang.Integer.
+	 * If this describes a java.util.List<?> and the element argument is a java.lang.Integer, the returned TypeDescriptor will be java.lang.Integer as well.
+	 * Annotation and nested type context will be preserved in the narrowed TypeDescriptor that is returned. 
 	 * @param element the collection or array element
-	 * @return the element type descriptor
+	 * @return a element type descriptor, narrowed to the type of the provided element
+	 * @throws IllegalStateException if this type is not a java.util.Collection or Array type
+	 * @see #narrow(Object)
 	 */
 	public TypeDescriptor elementType(Object element) {
 		assertCollectionOrArray();
@@ -350,9 +356,15 @@ public class TypeDescriptor {
 	}
 
 	/**
-	 * Creates a mapKeyType descriptor from the provided map key.
+	 * If this type is a {@link Map}, creates a mapKeyType descriptor from the provided map key.
+	 * Narrows the {@link #getMapKeyType() mapKeyType} property to the class of the provided map key.
+	 * For example, if this describes a java.util.Map<java.lang.Number, java.lang.String< and the key argument is a java.lang.Integer, the returned TypeDescriptor will be java.lang.Integer.
+	 * If this describes a java.util.Map<?, ?> and the key argument is a java.lang.Integer, the returned TypeDescriptor will be java.lang.Integer as well.
+	 * Annotation and nested type context will be preserved in the narrowed TypeDescriptor that is returned. 
 	 * @param mapKey the map key
 	 * @return the map key type descriptor
+	 * @throws IllegalStateException if this type is not a java.util.Map.
+	 * @see #narrow(Object)
 	 */
 	public TypeDescriptor mapKeyType(Object mapKey) {
 		assertMap();
@@ -375,9 +387,14 @@ public class TypeDescriptor {
 	}
 
 	/**
-	 * Creates a mapValueType descriptor from the provided map value.
+	 * If this type is a {@link Map}, creates a mapValueType descriptor from the provided map value.
+	 * Narrows the {@link #getMapValueType() mapValueType} property to the class of the provided map value.
+	 * For example, if this describes a java.util.Map<java.lang.String, java.lang.Number< and the value argument is a java.lang.Integer, the returned TypeDescriptor will be java.lang.Integer.
+	 * If this describes a java.util.Map<?, ?> and the value argument is a java.lang.Integer, the returned TypeDescriptor will be java.lang.Integer as well.
+	 * Annotation and nested type context will be preserved in the narrowed TypeDescriptor that is returned. 
 	 * @param mapValue the map value
 	 * @return the map value type descriptor
+	 * @throws IllegalStateException if this type is not a java.util.Map. 
 	 */
 	public TypeDescriptor mapValueType(Object mapValue) {
 		assertMap();
@@ -473,6 +490,9 @@ public class TypeDescriptor {
 	private static TypeDescriptor nested(AbstractDescriptor descriptor, int nestingLevel) {
 		for (int i = 0; i < nestingLevel; i++) {
 			descriptor = descriptor.nested();
+			if (descriptor == null) {
+				return null;
+			}
 		}
 		return new TypeDescriptor(descriptor);		
 	}

org.springframework.core/src/test/java/org/springframework/core/convert/TypeDescriptorTests.java

@@ -514,6 +514,12 @@ public class TypeDescriptorTests {
 		assertEquals(String.class, t1.getType());
 	}
 
+	@Test(expected=IllegalStateException.class)
+	public void nestedTooManyLevels() throws Exception {
+		TypeDescriptor t1 = TypeDescriptor.nested(new MethodParameter(getClass().getMethod("test4", List.class), 0), 3);
+		assertEquals(String.class, t1.getType());
+	}
+
 	@Test(expected=IllegalStateException.class)
 	public void nestedMethodParameterTypeNotNestable() throws Exception {
 		TypeDescriptor.nested(new MethodParameter(getClass().getMethod("test5", String.class), 0), 2);
@@ -543,7 +549,20 @@ public class TypeDescriptorTests {
 	public void test5(String param1) {
 		
 	}
-	
+
+	@Test
+	public void nestedNotParameterized() throws Exception {
+		TypeDescriptor t1 = TypeDescriptor.nested(new MethodParameter(getClass().getMethod("test6", List.class), 0), 1);
+		assertEquals(List.class,t1.getType());
+		assertEquals("java.util.List<?>", t1.toString());
+		TypeDescriptor t2 = TypeDescriptor.nested(new MethodParameter(getClass().getMethod("test6", List.class), 0), 2);
+		assertNull(t2);
+	}
+
+	public void test6(List<List> param1) {
+		
+	}
+
 	@Test
 	public void nestedFieldTypeMapTwoLevels() throws Exception {
 		TypeDescriptor t1 = TypeDescriptor.nested(getClass().getField("test4"), 2);

org.springframework.expression/src/test/java/org/springframework/expression/spel/SpringEL300Tests.java

@@ -726,7 +726,6 @@ public class SpringEL300Tests extends ExpressionTestCase {
         String el1 = "ls.![#this.equals('abc')]";
         SpelExpression exp = parser.parseRaw(el1);
         List value = (List)exp.getValue(ctx);
-        System.out.println(value);
         // value is list containing [true,false]
         Assert.assertEquals(Boolean.class,value.get(0).getClass());
         TypeDescriptor evaluated = exp.getValueTypeDescriptor(ctx);