@Test public void testMapWithArrayReadWrite() throws Exception { LinkedMapWritable written = new LinkedMapWritable(); ArrayWritable array = new WritableArrayWritable(Text.class); array.set(new Writable[] { new Text("one") , new Text("two"), new Text("three")} ); written.put(new Text("foo"), array); FastByteArrayOutputStream out = new FastByteArrayOutputStream(); DataOutputStream da = new DataOutputStream(out); written.write(da); da.close(); LinkedMapWritable read = new LinkedMapWritable(); read.readFields(new DataInputStream(new FastByteArrayInputStream(out.bytes()))); assertThat(read.size(), is(written.size())); assertThat(read.toString(), is(written.toString())); }