MapWritable extends AbstractMapWritable implements Map<Writable, Writable> { @Override public String toString() { return instance.toString(); } MapWritable();  MapWritable(MapWritable other); @Override void clear(); @Override boolean containsKey(Object key); @Override boolean containsValue(Object value); @Override Set<Map.Entry<Writable, Writable>> entrySet(); @Override boolean equals(Object obj); @Override Writable get(Object key); @Override int hashCode(); @Override boolean isEmpty(); @Override Set<Writable> keySet(); @Override Writable put(Writable key, Writable value); @Override void putAll(Map<? extends Writable, ? extends Writable> t); @Override Writable remove(Object key); @Override int size(); @Override Collection<Writable> values(); @Override void write(DataOutput out); @Override void readFields(DataInput in); @Override String toString();  }
@Test public void testToString() { MapWritable map = new MapWritable(); final IntWritable key = new IntWritable(5); final Text value = new Text("value"); map.put(key, value); assertEquals("{5=value}", map.toString()); }