Java Reference
In-Depth Information
// You need to AND the returned value from the getModifiers() method with
// appropriate value returned from xxxModifiers() method of the Modifiers class
int mod = c.getModifiers() & Modifier.classModifiers();
String modifiers = Modifier.toString(mod);
It is straightforward to get the name of the superclass of a class. Use the
getSuperclass()
method of the
Class
class to get the reference of the superclass. Note that every class in Java has a superclass except the
Object
class. If the
getSuperclass()
method is invoked on the
Object
class, it returns
null
. Therefore, it is important that you check the
returned value of the
getSuperclass()
method for
null
reference before you try to use it to get its name. This check is
removed below for clarity. However, the code for the
ClassReflection
class has this check:
Class superClass = c.getSuperclass();
if (superClass != null) {
String superClassName = superClass.getSimpleName();
}
■
the
getSuperclass()
method of the
Class
class returns null when it represents the
Object
class, a class for an
interface such as
List.class
, and a class for a primitive type such as
int.class
,
void.class
, etc.
Tip
To get the names of all interfaces implemented by a class, you use the
getInterfaces()
method of the
Class
class. It returns an array of
Class
object. Each element in the array represents an interface implemented by the class.
To get the list of all interfaces, you need to loop through all the elements of this array. The
ClassReflection
class has
a
getClassInterfaces()
method that returns all interfaces implemented by a
Class
object separated by a comma.
// Get all interfaces implemented by c
Class[] interfaces = c.getInterfaces();
The
getClassDescription()
method of the
ClassReflection
class puts all parts of a class declaration into a
string and returns that string. The
main()
method of this class demonstrates how to use this class.
■
Java 8 added a method called
toGenericString()
to the
Class
class that returns a string describing the
class. the string contains the modifiers and type parameters for the class. the call
Person.class.toGenericString()
will return
public class com.jdojo.reflection.Person
.
Note
Reflecting on Fields
A field of a class is represented by an object of the
java.lang.reflect.Field
class. The following four methods in the
Class
class can be used to get information about the fields of a class:
Field[] getFields()
•
Field[] getDeclaredFields()
•
Field getField(String name)
•
Field getDeclaredField(String name)
•
