/** * Copyright 2005 The Apache Software Foundation * * 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 org.apache.hadoop.io;import java.io.*;import java.lang.reflect.Array;/** A Writable for arrays containing instances of a class. */public class ArrayWritable implements Writable {  private Class valueClass;  private Writable[] values;  public ArrayWritable() {    this.valueClass = null;  }  public ArrayWritable(Class valueClass) {    this.valueClass = valueClass;  }  public ArrayWritable(Class 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 void setValueClass(Class valueClass) {    if (valueClass != this.valueClass) {        this.valueClass = valueClass;        this.values = null;    }  }    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);    }  }}