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The java::defineclass Command
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The java::defineclass Command
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Usage:
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<DD><B>java::defineclass</B> <I>classData</I>
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The <B>java::defineclass</B> command is used to convert a string of bytes
into a Java Class object. The <I>classData</I> argument is a string of
bytes that compose a class. For example, the <I>classData</I>
string could be from reading a Java class file. The <I>classData</I>
argument could also be a reflected instance of a byte[] Java object.
The <I>ClassData</I> argument
is passed to the TclClassLoader, where the TclClassLoader attempts to
construct a Java Class object from the bytes. If <I>classData</I>
does not represent a valid class, <B>java::defineclass</B> returns a
null object, otherwise it will return a handle to the Java Class
object. A class is not valid if; the TclClassLoader cannot decifer a
class from <I>classData</I>, the class has already been loaded into the
VM, or if the class is in the reserved java package.
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The TclClassLoader maintains a cache of the Java Class objects loaded
by the <B>java::defineclass</B> routine. The name of the class, which
is stored within the class bytecodes, is extracted and is used to
reference the cached Java Class object. If the class name is used in
future calls (e.g. <B>java::new</B>) the class defined by
<I>classData</I> is used.
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Example:
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In this example, a Java class is read from the filesystem
and then defined using the <b>java::defineclass</b> command.
<code>
<pre>
set fd [open Foo.class r]
fconfigure $file -translation binary
set data [read $fd]
close $fd
# This returns a java.lang.Class object.
set class [java::defineclass $data]
# Get an instance of the object by invoking the
# java.lang.Class.newInstance() method.
set object [$class newInstance]
# The class is now loaded into the VM, so we
# can also create instances of it by name
set object [java::new Foo]
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<A HREF="../license.html">Copyright</A> © 1997-1998 Sun Microsystems, Inc.
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