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The java::listify Command
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<H3>
The java::listify Command
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<H3>
Usage:
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<DD><B>java::listify</B> ?-noconvert|<I>class</I>? <I>collectionORenumeration</I>

<P>

The <B>java::listify</B> command trasforms a java <I>collection</I> or a java <I>enumeration</I> in a tcl-list.<BR>

<p>
The <I>collectionORenumertion</I> object is a handle to a Java object that implements the <code>java.util.Collection</code>
interface or the <code>java.util.Enumeration</code> interface, or an handle to <B>null</B> 
</p>
If <I>CollectionOrenumeration</I> is an handle to <B>null</B>, <B>java::listify</B> returns an empty list.
<P>
The <B>java::listify</B> command is similar to the <B>getrange</B> method working
on a java-array, except that elements can be of different classes.

<p>
In its simpler form (without <B>-noconvert</B>> or <I>class</I>),<B>java::listify</B>
tries to convert the enum/collections's elements in simple tcl-types (i.e. strings !).
<BR>
This implicit conversions works only on basic elements (i.e. Integer, Double, .., String);
otherwise the element is extracted as a java-object.
<BR>
Note that <B>null</B> elements are converted to the empty string.
</p>

<p>
If <B>-noconvert</B> option is used, then all <I>collection</I>'s elements are returned
as java.objects.
<BR>
If <I>class</I> is specified, then all <I>collection</I>'s elements are returned
as <I>casted</I> java.objects. An error is raised if <I>class</I> is incompatible with any element.
</p>


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<H3>Examples:</H3>

<DD>

<H4>
Collection Example:
</H4>

<P>
Assume for a moment that the user has defined a Java class.
This class contains a static method that returns a
collection object. The JDK 1.5 code to iterate over this
collection would be:

<code>
<pre>
Collection&lt;String&gt; c = MyJavaClass.getCollection();

for (String elem : c) {
    System.out.println("elem is " + elem);
}
</pre>
</code>

This same iteration could be implemented in Tcl, using
the <b>java::listify</b> command.

<code>
<pre>
set c [java::call MyJavaClass getCollection]

foreach elem [java::listify {String} $c] {
    puts "elem is $elem"
}
</pre>
</code>

</P>

<H4>
Elements in a Hashtable:
</H4>

<P>
The <B>java::listify</B> command can be used to iterate
over elements in a Hashtable or any other Map implementation.

<code>
<pre>
java::import -package java.util Hashtable Map
set t [java::new Hashtable]
$t put "One" "onestr"
$t put "Two" "twostr"

foreach e [java::listify {java.util.Map.Entry} [$t entrySet]] {
    set key [[$e getKey] toString]
    set value [[$e getValue] toString]
    puts "$key -> $value"
}
</pre>
</code>

The code above will print the following to the console:

<code>
<pre>
One -> onestr
Two -> twostr
</pre>
</code>

</P>


<H4>
Automatic Type Conversion:
</H4>

<P>
The <B>java::listify</B> command supports automatic conversion
of a Java primitive wrapper in a collection to a Tcl
value. For example, given a Vector of <code>java.lang.Integer</code>,
its elements are automatically converted in Tcl-integers.

<code>
<pre>
set v [java::new java.util.Vector]
$v addElement [java::new Integer 0]
$v addElement [java::new Integer 1]
$v addElement [java::new Integer 2]

puts "vector elements are: [java::listify $v]"
</pre>
</code>

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<PRE>
Based on TclBlend <A HREF="../license.html">Copyright</A> &#169; 1997-1998 Sun Microsystems, Inc.
</PRE>
<pre>JBlend is Copyright &copy; 2016 - Irrational Numbers.<br></pre>

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