|
/**
*
* JFreeReport : a free Java reporting library
*
*
* Project Info: http://reporting.pentaho.org/
*
* (C) Copyright 2001-2007, by Object Refinery Ltd, Pentaho Corporation and Contributors.
*
* This library is free software; you can redistribute it and/or modify it under the terms
* of the GNU Lesser General Public License as published by the Free Software Foundation;
* either version 2.1 of the License, or (at your option) any later version.
*
* This library 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License along with this
* library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307, USA.
*
* [Java is a trademark or registered trademark of Sun Microsystems, Inc.
* in the United States and other countries.]
*
* ------------
* PropertiesIterator.java
* ------------
* (C) Copyright 2001-2007, by Object Refinery Ltd, Pentaho Corporation and Contributors.
*/
import java.util.Iterator;
import java.util.Properties;
/**
* The properties iterator iterates over a set of enumerated properties. The
* properties are named by an optional prefix plus a number, which is counted up
* on each iteration: <p/>
* <ul>
* <li>prefix_0 </li>
* <li>prefix_1 </li>
* <li>prefix_2 </li>
* <li>... </li>
* </ul>
* <p/> The iterator iterates over all subsequent numbered proprties until the
* number-sequence is finished.
*
* @author Thomas Morgner
*
*/
public class PropertiesIterator implements Iterator {
/**
* The underlying properties collection.
*/
private Properties properties;
/**
* The property name prefix.
*/
private String prefix;
/**
* An incremental counter.
*/
private int count;
/**
* Creates a new properties iterator without an prefix.
*
* @param properties
* the underlying properties collection.
*/
public PropertiesIterator(final Properties properties) {
this(properties, null);
}
/**
* Creates a new properties iterator with the given prefix.
*
* @param properties
* the underlying properties collection.
* @param prefix
* a prefix for generating property names (null permitted).
*/
public PropertiesIterator(final Properties properties, final String prefix) {
if (properties == null) {
throw new NullPointerException();
}
this.properties = properties;
this.prefix = prefix;
this.count = 0;
}
/**
* Returns true if there is a property in the underlying collection with a
* name that matches the name returned by the getNextKey() method.
*
* @return true if there is another property with a name in the correct form.
*/
public boolean hasNext() {
return properties.containsKey(getNextKey());
}
/**
* Generates a property name in the form <prefix>
* <count>.
*
* The <count> begins at 0,
* and is automatically incremented with each call to the next() method.
*
* @return the next key in the sequence
*
*/
private String getNextKey() {
if (prefix == null) {
return String.valueOf(count);
}
return prefix + String.valueOf(count);
}
/**
* Returns the property with a name the same as the name generated by the
* getNextKey() method, or null if there is no such property (that is, then
* end of the sequence has been reached).
*
* @return the property or null.
*/
public Object next() {
final String value = properties.getProperty(getNextKey());
count++;
return value;
}
/**
* Always throws UnsupportedOperationException as remove is not implemented
* for this iterator.
*
* @throws UnsupportedOperationException
* as remove is not supported.
*/
public void remove() {
throw new UnsupportedOperationException();
}
}
|