[Chapter 25] 25.8 java.lang.Class (JDK 1.0)

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| Chapter 25 The java.lang Package |

## 25.8 java.lang.Class (JDK 1.0)

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This class represents a Java class or interface, or, in Java 1.1, any Java type. There is one `Class` object for each class that is loaded into the Java Virtual Machine, and in Java 1.1 there are special `Class` objects that represent the Java primitive types. The `TYPE` constants defined by `Boolean`, `Integer`, and the other primitive "wrapper classes" hold these special `Class` objects. Array types are also represented by `Class` objects in Java 1.1.

There is no constructor for this class. You can obtain a `Class` object by calling the `getClass()` method of any instance of the desired class. In Java 1.1, a `Class` object may also be referred to by appending `.class` to the name of a class. Finally, and most interestingly, a class can be dynamically loaded by passing its fully-qualified name (i.e., package name plus class name) to the static `Class.forName()` method. This method loads the named class, if it is not already loaded, into the Java interpreter, and returns a `Class` object for it.

The `newInstance()` method creates an instance of a given class--this allows you to create instances of dynamically loaded classes for which you cannot use the `new` keyword. Note that this method only works when the target class has a no-argument constructor. See `newInstance()` in `java.lang.reflect.Constructor` for a more powerful way to instantiate dynamically loaded classes.

`getName()` returns the name of the class. `getSuperclass()` returns its superclass. `isInterface()` tests whether the `Class` object represents an interface, and `getInterfaces()` returns an array of the interfaces that this class implements. The various other `get` and `is` methods return other information about the represented class, and form part of the Java Reflection API, along with the classes in `java.lang.reflect`.

    public final class Class extends Object implements Serializable {
        // No Constructor
        // Class Methods
                public static native Class forName(String className) throws ClassNotFoundException;
        // Public Instance Methods
                public native ClassLoader getClassLoader();
            1.1public Class[] getClasses();
            1.1public native Class getComponentType();
            1.1public Constructor getConstructor(Class[] parameterTypes) throws NoSuchMethodException, SecurityException;
            1.1public Constructor[] getConstructors() throws SecurityException;
            1.1public Class[] getDeclaredClasses() throws SecurityException;
            1.1public Constructor getDeclaredConstructor(Class[] parameterTypes) throws NoSuchMethodException, SecurityException;
            1.1public Constructor[] getDeclaredConstructors() throws SecurityException;
            1.1public Field getDeclaredField(String name) throws NoSuchFieldException, SecurityException;
            1.1public Field[] getDeclaredFields() throws SecurityException;
            1.1public Method getDeclaredMethod(String name, Class[] parameterTypes) throws NoSuchMethodException, SecurityException;
            1.1public Method[] getDeclaredMethods() throws SecurityException;
            1.1public Class getDeclaringClass();
            1.1public Field getField(String name) throws NoSuchFieldException, SecurityException;
            1.1public Field[] getFields() throws SecurityException;
                public native Class[] getInterfaces();
            1.1public Method getMethod(String name, Class[] parameterTypes) throws NoSuchMethodException, SecurityException;
            1.1public Method[] getMethods() throws SecurityException;
            1.1public native int getModifiers();
                public native String getName();
            1.1public URL getResource(String name);
            1.1public InputStream getResourceAsStream(String name);
            1.1public native Object[] getSigners();
                public native Class getSuperclass();
            1.1public native boolean isArray();
            1.1public native boolean isAssignableFrom(Class cls);
            1.1public native boolean isInstance(Object obj);
                public native boolean isInterface();
            1.1public native boolean isPrimitive();
                public native Object newInstance() throws InstantiationException, IllegalAccessException;
                public String toString();  // Overrides Object
    }

### Passed To:

Array.newInstance(), BeanDescriptor(), Beans.getInstanceOf(), Beans.isInstanceOf(), Class.getConstructor(), Class.getDeclaredConstructor(), Class.getDeclaredMethod(), Class.getMethod(), Class.isAssignableFrom(), ClassLoader.resolveClass(), ClassLoader.setSigners(), Compiler.compileClass(), DataFlavor(), EventSetDescriptor(), IndexedPropertyDescriptor(), Introspector.getBeanInfo(), ObjectOutputStream.annotateClass(), ObjectStreamClass.lookup(), PropertyDescriptor(), PropertyDescriptor.setPropertyEditorClass(), PropertyEditorManager.findEditor(), PropertyEditorManager.registerEditor(), SecurityManager.checkMemberAccess()

### Returned By:

BeanDescriptor.getBeanClass(), BeanDescriptor.getCustomizerClass(), Class.forName(), Class.getClasses(), Class.getComponentType(), Class.getDeclaredClasses(), Class.getDeclaringClass(), Class.getInterfaces(), Class.getSuperclass(), ClassLoader.defineClass(), ClassLoader.findLoadedClass(), ClassLoader.findSystemClass(), ClassLoader.loadClass(), Constructor.getDeclaringClass(), Constructor.getExceptionTypes(), Constructor.getParameterTypes(), DataFlavor.getRepresentationClass(), EventSetDescriptor.getListenerType(), Field.getDeclaringClass(), Field.getType(), IndexedPropertyDescriptor.getIndexedPropertyType(), Member.getDeclaringClass(), Method.getDeclaringClass(), Method.getExceptionTypes(), Method.getParameterTypes(), Method.getReturnType(), Object.getClass(), ObjectInputStream.resolveClass(), ObjectStreamClass.forClass(), PropertyDescriptor.getPropertyEditorClass(), PropertyDescriptor.getPropertyType(), SecurityManager.currentLoadedClass(), SecurityManager.getClassContext()

### Type Of:

Boolean.TYPE, Byte.TYPE, Character.TYPE, Double.TYPE, Float.TYPE, Integer.TYPE, Long.TYPE, Short.TYPE, Void.TYPE

java.lang.Character (JDK 1.0) |  | java.lang.ClassCastException (JDK 1.0)