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Object Automation library
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/*  Copyright 1999 Vince Via [email protected]
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
*/
package com.viaoa.hub;

/**
 * This will populate a Hub with the top N objects in another Hub.
 * @author vvia
 *
 */
public class HubSample {
    protected final Hub hubMaster;
    protected final Hub hubSample;
    protected final int amtSample;
    protected HubListener hubListener;

    /**
     * Create a hubSample instance.
     * @param hubMaster
     * @param hubSample will always be populated with hubMaster<0> .. 
     * @param sampleAmount number of objects in hubMaster to have in hubSample
     */
    public HubSample(Hub hubMaster, Hub hubSample, int sampleAmount) {
        this.hubMaster = hubMaster;
        this.hubSample = hubSample;
        this.amtSample = sampleAmount;
        setup();
    }
    
    protected void setup() {
        if (hubMaster == null && hubSample == null) return;
        hubListener = new HubListenerAdapter() {
            @Override
            public void afterAdd(HubEvent e) {
                int pos = hubMaster.getPos();
                if (e.getPos() < amtSample) refresh();
            }
            @Override
            public void afterInsert(HubEvent e) {
                if (e.getPos() < amtSample) refresh();
            }
            @Override
            public void afterNewList(HubEvent e) {
                refresh();
            }
            @Override
            public void afterRemove(HubEvent e) {
                if (e.getPos() < amtSample) refresh();
            }
            @Override
            public void afterRemoveAll(HubEvent e) {
                refresh();
            }
            @Override
            public void afterSort(HubEvent e) {
                refresh();
            }
        };
        hubMaster.addHubListener(hubListener);
        refresh();
    }
    
    protected void refresh() {
        for (int i=0; i amtSample) ; ) {
            hubSample.remove(amtSample);
        }
    }
    
    public void close() {
        if (hubListener != null) {
            hubMaster.removeListener(hubListener);
            hubListener = null;
        }
    }
    
    @Override
    protected void finalize() throws Throwable {
        close();
        super.finalize();
    }
    
}