org.apache.hadoop.hdfs.protocol.DirectoryListing.java Source code

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Here is the source code for org.apache.hadoop.hdfs.protocol.DirectoryListing.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.hadoop.hdfs.protocol;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;

/**
 * This class defines a partial listing of a directory to support
 * iterative directory listing.
 */
@InterfaceAudience.Private
@InterfaceStability.Evolving
public class DirectoryListing {
    private HdfsFileStatus[] partialListing;
    private int remainingEntries;

    /**
     * constructor
     * @param partialListing a partial listing of a directory
     * @param remainingEntries number of entries that are left to be listed
     */
    public DirectoryListing(HdfsFileStatus[] partialListing, int remainingEntries) {
        if (partialListing == null) {
            throw new IllegalArgumentException("partial listing should not be null");
        }
        if (partialListing.length == 0 && remainingEntries != 0) {
            throw new IllegalArgumentException(
                    "Partial listing is empty but " + "the number of remaining entries is not zero");
        }
        this.partialListing = partialListing;
        this.remainingEntries = remainingEntries;
    }

    /**
     * Get the partial listing of file status
     * @return the partial listing of file status
     */
    public HdfsFileStatus[] getPartialListing() {
        return partialListing;
    }

    /**
     * Get the number of remaining entries that are left to be listed
     * @return the number of remaining entries that are left to be listed
     */
    public int getRemainingEntries() {
        return remainingEntries;
    }

    /**
     * Check if there are more entries that are left to be listed
     * @return true if there are more entries that are left to be listed;
     *         return false otherwise.
     */
    public boolean hasMore() {
        return remainingEntries != 0;
    }

    /**
     * Get the last name in this list
     * @return the last name in the list if it is not empty; otherwise return null
     */
    public byte[] getLastName() {
        if (partialListing.length == 0) {
            return null;
        }
        return partialListing[partialListing.length - 1].getLocalNameInBytes();
    }
}