Java 类org.apache.commons.collections.iterators.EmptyListIterator 实例源码

/**
 * Used for exception example
 */
@SuppressWarnings({ "unchecked", "unused" })
private void return_empty_list_iterator_apache_commons_exception () {

    DomainObject domain = null; // dao populate domain

    ListIterator<String> strings;
    if (domain != null && !CollectionUtils.sizeIsEmpty(domain.getStrings())) {
        strings = domain.getStrings();
    } else {
        strings = EmptyListIterator.INSTANCE;
    }

    //...
}

@Override
public Iterator<Tuple2<Long,Tuple2<byte[], byte[]>>> call(ExecRow execRow) throws Exception {
    if (!initialized) {
        encoder = new PairEncoder(getKeyEncoder(), getRowHash(), dataType);
        int i = 0;
        indexTransformFunctions = new IndexTransformFunction[tentativeIndices.size()];
        for (DDLMessage.TentativeIndex index: tentativeIndices) {
            indexTransformFunctions[i] = new IndexTransformFunction(index);
            i++;
        }
        initialized = true;
    }

    try {
        ArrayList<Tuple2<Long,Tuple2<byte[], byte[]>>> list = new ArrayList();
        KVPair mainRow = encoder.encode(execRow);
        list.add(new Tuple2<>(heapConglom,new Tuple2<>(mainRow.getRowKey(), mainRow.getValue())));
        for (int i = 0; i< indexTransformFunctions.length; i++) {
            ExecRow indexRow = getIndexRow(indexTransformFunctions[i], execRow);
            indexRow.setKey(mainRow.rowKeySlice().array());
            Long indexConglomerate = indexTransformFunctions[i].getIndexConglomerateId();
            KVPair indexKVPair = indexTransformFunctions[i].call(indexRow);
            if (indexKVPair != null) // Supports Null and Default Expression Indexes
                list.add(new Tuple2<>(indexConglomerate, new Tuple2<>(indexKVPair.getRowKey(), indexKVPair.getValue())));
        }
        return list.iterator();

    } catch (Exception e) {
        if (operationContext!=null && operationContext.isPermissive()) {
            operationContext.recordBadRecord(e.getLocalizedMessage() + execRow.toString(), e);
            return EmptyListIterator.INSTANCE;
        }
        throw Exceptions.parseException(e);
    }
}

/**
 * Used for exception example
 */
@SuppressWarnings({ "unchecked", "unused" })
private void return_empty_list_iterator_apache_commons_exception () {

    DomainObject domain = null; // dao populate domain

    ListIterator<String> strings;
    if (domain != null && !CollectionUtils.sizeIsEmpty(domain.getStrings())) {
        strings = domain.getStrings();
    } else {
        strings = EmptyListIterator.INSTANCE;
    }

    //...
}