001/** 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018 019package org.apache.hadoop.io; 020 021import java.io.*; 022import java.lang.reflect.Array; 023 024import org.apache.hadoop.classification.InterfaceAudience; 025import org.apache.hadoop.classification.InterfaceStability; 026 027/** A Writable for 2D arrays containing a matrix of instances of a class. */ 028@InterfaceAudience.Public 029@InterfaceStability.Stable 030public class TwoDArrayWritable implements Writable { 031 private Class valueClass; 032 private Writable[][] values; 033 034 public TwoDArrayWritable(Class valueClass) { 035 this.valueClass = valueClass; 036 } 037 038 public TwoDArrayWritable(Class valueClass, Writable[][] values) { 039 this(valueClass); 040 this.values = values; 041 } 042 043 public Object toArray() { 044 int dimensions[] = {values.length, 0}; 045 Object result = Array.newInstance(valueClass, dimensions); 046 for (int i = 0; i < values.length; i++) { 047 Object resultRow = Array.newInstance(valueClass, values[i].length); 048 Array.set(result, i, resultRow); 049 for (int j = 0; j < values[i].length; j++) { 050 Array.set(resultRow, j, values[i][j]); 051 } 052 } 053 return result; 054 } 055 056 public void set(Writable[][] values) { this.values = values; } 057 058 public Writable[][] get() { return values; } 059 060 @Override 061 public void readFields(DataInput in) throws IOException { 062 // construct matrix 063 values = new Writable[in.readInt()][]; 064 for (int i = 0; i < values.length; i++) { 065 values[i] = new Writable[in.readInt()]; 066 } 067 068 // construct values 069 for (int i = 0; i < values.length; i++) { 070 for (int j = 0; j < values[i].length; j++) { 071 Writable value; // construct value 072 try { 073 value = (Writable)valueClass.newInstance(); 074 } catch (InstantiationException e) { 075 throw new RuntimeException(e.toString()); 076 } catch (IllegalAccessException e) { 077 throw new RuntimeException(e.toString()); 078 } 079 value.readFields(in); // read a value 080 values[i][j] = value; // store it in values 081 } 082 } 083 } 084 085 @Override 086 public void write(DataOutput out) throws IOException { 087 out.writeInt(values.length); // write values 088 for (int i = 0; i < values.length; i++) { 089 out.writeInt(values[i].length); 090 } 091 for (int i = 0; i < values.length; i++) { 092 for (int j = 0; j < values[i].length; j++) { 093 values[i][j].write(out); 094 } 095 } 096 } 097} 098