/** * 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 2D arrays containing a matrix of instances of a class. */public class TwoDArrayWritable implements Writable {  private Class valueClass;  private Writable[][] values;  public TwoDArrayWritable(Class valueClass) {    this.valueClass = valueClass;  }  public TwoDArrayWritable(Class valueClass, Writable[][] values) {    this(valueClass);    this.values = values;  }  public Object toArray() {      int dimensions[] = {values.length, 0};      Object result = Array.newInstance(valueClass, dimensions);      for (int i = 0; i < values.length; i++) {          Object resultRow = Array.newInstance(valueClass, values[i].length);          Array.set(result, i, resultRow);          for (int j = 0; j < values[i].length; j++) {              Array.set(resultRow, j, values[i][j]);          }      }      return result;  }  public void set(Writable[][] values) { this.values = values; }  public Writable[][] get() { return values; }  public void readFields(DataInput in) throws IOException {    // construct matrix    values = new Writable[in.readInt()][];              for (int i = 0; i < values.length; i++) {        values[i] = new Writable[in.readInt()];    }    // construct values    for (int i = 0; i < values.length; i++) {        for (int j = 0; j < values[i].length; j++) {            Writable value;                             // construct value            try {                value = (Writable)valueClass.newInstance();            } catch (InstantiationException e) {                throw new RuntimeException(e.toString());            } catch (IllegalAccessException e) {                throw new RuntimeException(e.toString());            }            value.readFields(in);                       // read a value            values[i][j] = 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++) {        out.writeInt(values[i].length);    }    for (int i = 0; i < values.length; i++) {        for (int j = 0; j < values[i].length; j++) {            values[i][j].write(out);        }    }  }}