/*
*
*
* Copyright 1990-2007 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 only, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License version 2 for more details (a copy is
* included at /legal/license.txt).
*
* You should have received a copy of the GNU General Public License
* version 2 along with this work; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
* Clara, CA 95054 or visit www.sun.com if you need additional
* information or have any questions.
*/
package java.lang;
/**
* Instances of the class <code>Class</code> represent classes and interfaces
* in a running Java application. Every array also belongs to a class that is
* reflected as a <code>Class</code> object that is shared by all arrays with
* the same element type and number of dimensions.
*
* <p> <code>Class</code> has no public constructor. Instead <code>Class</code>
* objects are constructed automatically by the Java Virtual Machine as classes
* are loaded.
*
* <p> The following example uses a <code>Class</code> object to print the
* class name of an object:
*
* <p> <blockquote><pre>
* void printClassName(Object obj) {
* System.out.println("The class of " + obj +
* " is " + obj.getClass().getName());
* }
* </pre></blockquote>
*
* @version 12/17/01 (CLDC 1.1)
* @since JDK1.0, CLDC 1.0
*/
public final
class Class {
/*
* Constructor. Only the Java Virtual Machine creates Class
* objects.
*/
private Class() {}
/**
* Converts the object to a string. The string representation is the
* string "class" or "interface", followed by a space, and then by the
* fully qualified name of the class in the format returned by
* <code>getName</code>. If this <code>Class</code> object represents a
* primitive type, this method returns the name of the primitive type. If
* this <code>Class</code> object represents void this method returns
* "void".
*
* @return a string representation of this class object.
*/
public String toString() {
return (isInterface() ? "interface " : "class ") + getName();
}
/**
* Returns the <code>Class</code> object associated with the class
* with the given string name. Given the fully-qualified name for
* a class or interface, this method attempts to locate, load and
* link the class.
* <p>
* For example, the following code fragment returns the runtime
* <code>Class</code> descriptor for the class named
* <code>java.lang.Thread</code>:
* <ul><code>
* Class t = Class.forName("java.lang.Thread")
* </code></ul>
*
* @param className the fully qualified name of the desired class.
* @return the <code>Class</code> object for the class with the
* specified name.
* @exception ClassNotFoundException if the class could not be found.
* @exception Error if the function fails for any other reason.
* @since JDK1.0
*/
public static native Class forName(String className)
throws ClassNotFoundException;
/**
* Creates a new instance of a class.
*
* @return a newly allocated instance of the class represented by this
* object. This is done exactly as if by a <code>new</code>
* expression with an empty argument list.
* @exception IllegalAccessException if the class or initializer is
* not accessible.
* @exception InstantiationException if an application tries to
* instantiate an abstract class or an interface, or if the
* instantiation fails for some other reason.
* @since JDK1.0
*/
public native Object newInstance()
throws InstantiationException, IllegalAccessException;
/**
* Determines if the specified <code>Object</code> is assignment-compatible
* with the object represented by this <code>Class</code>. This method is
* the dynamic equivalent of the Java language <code>instanceof</code>
* operator. The method returns <code>true</code> if the specified
* <code>Object</code> argument is non-null and can be cast to the
* reference type represented by this <code>Class</code> object without
* raising a <code>ClassCastException.</code> It returns <code>false</code>
* otherwise.
*
* <p> Specifically, if this <code>Class</code> object represents a
* declared class, this method returns <code>true</code> if the specified
* <code>Object</code> argument is an instance of the represented class (or
* of any of its subclasses); it returns <code>false</code> otherwise. If
* this <code>Class</code> object represents an array class, this method
* returns <code>true</code> if the specified <code>Object</code> argument
* can be converted to an object of the array class by an identity
* conversion or by a widening reference conversion; it returns
* <code>false</code> otherwise. If this <code>Class</code> object
* represents an interface, this method returns <code>true</code> if the
* class or any superclass of the specified <code>Object</code> argument
* implements this interface; it returns <code>false</code> otherwise. If
* this <code>Class</code> object represents a primitive type, this method
* returns <code>false</code>.
*
* @param obj the object to check
* @return true if <code>obj</code> is an instance of this class
*
* @since JDK1.1
*/
public native boolean isInstance(Object obj);
/**
* Determines if the class or interface represented by this
* <code>Class</code> object is either the same as, or is a superclass or
* superinterface of, the class or interface represented by the specified
* <code>Class</code> parameter. It returns <code>true</code> if so;
* otherwise it returns <code>false</code>. If this <code>Class</code>
* object represents a primitive type, this method returns
* <code>true</code> if the specified <code>Class</code> parameter is
* exactly this <code>Class</code> object; otherwise it returns
* <code>false</code>.
*
* <p> Specifically, this method tests whether the type represented by the
* specified <code>Class</code> parameter can be converted to the type
* represented by this <code>Class</code> object via an identity conversion
* or via a widening reference conversion. See <em>The Java Language
* Specification</em>, sections 5.1.1 and 5.1.4 , for details.
*
* @param cls the <code>Class</code> object to be checked
* @return the <code>boolean</code> value indicating whether objects of the
* type <code>cls</code> can be assigned to objects of this class
* @exception NullPointerException if the specified Class parameter is
* null.
* @since JDK1.1
*/
public native boolean isAssignableFrom(Class cls);
/**
* Determines if the specified <code>Class</code> object represents an
* interface type.
*
* @return <code>true</code> if this object represents an interface;
* <code>false</code> otherwise.
*/
public native boolean isInterface();
/**
* Determines if this <code>Class</code> object represents an array class.
*
* @return <code>true</code> if this object represents an array class;
* <code>false</code> otherwise.
* @since JDK1.1
*/
public native boolean isArray();
/**
* Returns the fully-qualified name of the entity (class, interface, array
* class, primitive type, or void) represented by this <code>Class</code>
* object, as a <code>String</code>.
*
* <p> If this <code>Class</code> object represents a class of arrays, then
* the internal form of the name consists of the name of the element type
* in Java signature format, preceded by one or more "<tt>[</tt>"
* characters representing the depth of array nesting. Thus:
*
* <blockquote><pre>
* (new Object[3]).getClass().getName()
* </pre></blockquote>
*
* returns "<code>[Ljava.lang.Object;</code>" and:
*
* <blockquote><pre>
* (new int[3][4][5][6][7][8][9]).getClass().getName()
* </pre></blockquote>
*
* returns "<code>[[[[[[[I</code>". The encoding of element type names
* is as follows:
*
* <blockquote><pre>
* B byte
* C char
* D double
* F float
* I int
* J long
* L<i>classname;</i> class or interface
* S short
* Z boolean
* </pre></blockquote>
*
* The class or interface name <tt><i>classname</i></tt> is given in fully
* qualified form as shown in the example above.
*
* @return the fully qualified name of the class or interface
* represented by this object.
*/
public native String getName();
/**
* Finds a resource with a given name in the application's
* JAR file. This method returns
* <code>null</code> if no resource with this name is found
* in the application's JAR file.
* <p>
* The resource names can be represented in two
* different formats: absolute or relative.
* <p>
* Absolute format:
* <ul><code>/packagePathName/resourceName</code></ul>
* <p>
* Relative format:
* <ul><code>resourceName</code></ul>
* <p>
* In the absolute format, the programmer provides a fully
* qualified name that includes both the full path and the
* name of the resource inside the JAR file. In the path names,
* the character "/" is used as the separator.
* <p>
* In the relative format, the programmer provides only
* the name of the actual resource. Relative names are
* converted to absolute names by the system by prepending
* the resource name with the fully qualified package name
* of class upon which the <code>getResourceAsStream</code>
* method was called.
*
* @param name name of the desired resource
* @return a <code>java.io.InputStream</code> object.
*/
public java.io.InputStream getResourceAsStream(String name) {
try {
if (name.length() > 0 && name.charAt(0) == '/') {
/* Absolute format */
name = name.substring(1);
} else {
/* Relative format */
String className = this.getName();
int dotIndex = className.lastIndexOf('.');
if (dotIndex >= 0) {
name = className.substring(0, dotIndex + 1).replace('.', '/')
+ name;
}
}
return new com.sun.cldc.io.ResourceInputStream(name);
} catch (java.io.IOException x) {
return null;
}
}
/*
* This private function is used during virtual machine initialization.
* The user does not normally see this function.
*/
// private static void runCustomCode() {}
/* The code below is specific to this VM */
/**
* Returns the <code>Class</code> representing the superclass of the entity
* (class, interface, primitive type or void) represented by this
* <code>Class</code>. If this <code>Class</code> represents either the
* <code>Object</code> class, an interface, a primitive type, or void, then
* null is returned. If this object represents an array class then the
* <code>Class</code> object representing the <code>Object</code> class is
* returned.
*
* Note that this method is not supported by CLDC.
* We have made the method private, since it is
* needed by our implementation.
*
* @return the superclass of the class represented by this object.
*/
private native Class getSuperclass();
/*
* This private variable is used by the VM.
* Users never see it.
*/
private transient Object vmClass;
private int status;
private Thread thread;
private static final int IN_PROGRESS = 1;
private static final int VERIFIED = 2;
private static final int INITIALIZED = 4;
private static final int ERROR = 8;
// Native for invoking <clinit>
private native void invoke_clinit();
/**
* Initialization at step 9:
* If ENABLE_ISOLATES == false
* Remove the <clinit> method after the class is initialized.
* If ENABLE_ISOLATES == true, clear class initialization
* barrier.
*/
private native void init9();
private native void invoke_verify();
/*
* Implements the 11 step program detailed in Java Language Specification
* 12.4.2
*/
void initialize() throws Throwable {
// Step 1
synchronized (this) {
// Step 2
while ((status & IN_PROGRESS) != 0 && thread != Thread.currentThread()) {
try{
wait();
} catch (InterruptedException e) {
}
}
// Step 3
if ((status & IN_PROGRESS) != 0 && thread == Thread.currentThread()) {
return;
}
// Step 4
if ((status & INITIALIZED) != 0) {
return;
}
// Step 5
if (status == ERROR) {
throw new NoClassDefFoundError(getName());
}
/* Note: CLDC 1.0 does not have NoClassDefFoundError class */
// Step 6
status |= IN_PROGRESS;
thread = Thread.currentThread();
}
try {
// Step 7
invoke_verify();
Class s = getSuperclass();
if (s != null && (s.status & INITIALIZED) == 0) {
// The test of s.status is not part of the spec, but
// it saves us doing a lot of work in the most common
// case.
s.initialize();
}
// Step 8
invoke_clinit();
// Step 9
synchronized (this) {
status &= ~IN_PROGRESS;
status |= INITIALIZED;
thread = null;
init9();
notifyAll();
}
} catch(Throwable e) {
// Step 10 and 11
// CR 6224346, The cldc_vm threading mechanism is such that
// we can just jam these values in without fear of another
// thread doing the same since only this thread can be
// executing the initialize() method and the scheduler is
// non-preemptive. We do this here in case the monitorenter
// fails due to OOME because some other thread holds the lock,
// memory is low and we need to allocate a ConditionDesc to
// wait for the lock.
status = ERROR;
thread = null;
synchronized (this) {
notifyAll();
throwError(e);
}
}
}
private Error throwError(Throwable e) throws Error {
throw (e instanceof Error) ? (Error)e
: new Error("Static initializer: " + e.getClass().getName() +
", " + e.getMessage());
}
}
|
