com.adobe.granite.ui.components.ds.EmptyDataSource Maven / Gradle / Ivy

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package com.adobe.granite.ui.components.ds;

import java.util.Iterator;
import java.util.NoSuchElementException;

import org.apache.sling.api.resource.Resource;

/**
 * A datasource that has empty data.
 */
public final class EmptyDataSource implements DataSource {
    private static DataSource instance;

    /**
     * Returns the singleton instance.
     * @return the singleton instance
     */
    public static DataSource instance() {
        if (instance == null) {
            instance = new EmptyDataSource();
        }

        return instance;
    }

    private EmptyDataSource() {
    }

    public Iterator iterator() {
        return new Iterator() {
            public void remove() {
                throw new UnsupportedOperationException("Empty iterator");
            }

            public Resource next() {
                throw new NoSuchElementException("Empty iterator");
            }

            public boolean hasNext() {
                return false;
            }
        };
    }
}