| /** |
| * 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.io; |
| |
| import java.io.*; |
| import java.lang.reflect.Array; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| |
| /** |
| * A Writable for arrays containing instances of a class. The elements of this |
| * writable must all be instances of the same class. If this writable will be |
| * the input for a Reducer, you will need to create a subclass that sets the |
| * value to be of the proper type. |
| * |
| * For example: |
| * <code> |
| * public class IntArrayWritable extends ArrayWritable { |
| * public IntArrayWritable() { |
| * super(IntWritable.class); |
| * } |
| * } |
| * </code> |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Stable |
| public class ArrayWritable implements Writable { |
| private Class<? extends Writable> valueClass; |
| private Writable[] values; |
| |
| public ArrayWritable(Class<? extends Writable> valueClass) { |
| if (valueClass == null) { |
| throw new IllegalArgumentException("null valueClass"); |
| } |
| this.valueClass = valueClass; |
| } |
| |
| public ArrayWritable(Class<? extends Writable> valueClass, Writable[] values) { |
| this(valueClass); |
| this.values = values; |
| } |
| |
| public ArrayWritable(String[] strings) { |
| this(UTF8.class, new Writable[strings.length]); |
| for (int i = 0; i < strings.length; i++) { |
| values[i] = new UTF8(strings[i]); |
| } |
| } |
| |
| public Class getValueClass() { |
| return valueClass; |
| } |
| |
| public String[] toStrings() { |
| String[] strings = new String[values.length]; |
| for (int i = 0; i < values.length; i++) { |
| strings[i] = values[i].toString(); |
| } |
| return strings; |
| } |
| |
| public Object toArray() { |
| Object result = Array.newInstance(valueClass, values.length); |
| for (int i = 0; i < values.length; i++) { |
| Array.set(result, i, values[i]); |
| } |
| return result; |
| } |
| |
| public void set(Writable[] values) { this.values = values; } |
| |
| public Writable[] get() { return values; } |
| |
| public void readFields(DataInput in) throws IOException { |
| values = new Writable[in.readInt()]; // construct values |
| for (int i = 0; i < values.length; i++) { |
| Writable value = WritableFactories.newInstance(valueClass); |
| value.readFields(in); // read a value |
| values[i] = value; // store it in values |
| } |
| } |
| |
| public void write(DataOutput out) throws IOException { |
| out.writeInt(values.length); // write values |
| for (int i = 0; i < values.length; i++) { |
| values[i].write(out); |
| } |
| } |
| |
| } |
| |