Added comments, implemented interfaces for some added convenience.

src/main/java/ch/dissem/msgpack/types/MPArray.java

@@ -8,9 +8,19 @@ import java.io.OutputStream;
 import java.nio.ByteBuffer;
 import java.util.*;
 
-public class MPArray<T extends MPType> implements MPType<List<T>> {
+/**
+ * Representation of a msgpack encoded array. Uses a list to represent data internally, and implements the {@link List}
+ * interface for your convenience.
+ *
+ * @param <T>
+ */
+public class MPArray<T extends MPType> implements MPType<List<T>>, List<T> {
     private List<T> array;
 
+    public MPArray() {
+        this.array = new LinkedList<>();
+    }
+
     public MPArray(List<T> array) {
         this.array = array;
     }
@@ -39,6 +49,76 @@ public class MPArray<T extends MPType> implements MPType<List<T>> {
         }
     }
 
+    @Override
+    public int size() {
+        return array.size();
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return array.isEmpty();
+    }
+
+    @Override
+    public boolean contains(Object o) {
+        return array.contains(o);
+    }
+
+    @Override
+    public Iterator<T> iterator() {
+        return array.iterator();
+    }
+
+    @Override
+    public Object[] toArray() {
+        return array.toArray();
+    }
+
+    @Override
+    public <T1> T1[] toArray(T1[] t1s) {
+        return array.toArray(t1s);
+    }
+
+    @Override
+    public boolean add(T t) {
+        return array.add(t);
+    }
+
+    @Override
+    public boolean remove(Object o) {
+        return array.remove(o);
+    }
+
+    @Override
+    public boolean containsAll(Collection<?> collection) {
+        return array.containsAll(collection);
+    }
+
+    @Override
+    public boolean addAll(Collection<? extends T> collection) {
+        return array.addAll(collection);
+    }
+
+    @Override
+    public boolean addAll(int i, Collection<? extends T> collection) {
+        return array.addAll(i, collection);
+    }
+
+    @Override
+    public boolean removeAll(Collection<?> collection) {
+        return array.removeAll(collection);
+    }
+
+    @Override
+    public boolean retainAll(Collection<?> collection) {
+        return array.retainAll(collection);
+    }
+
+    @Override
+    public void clear() {
+        array.clear();
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
@@ -52,6 +132,51 @@ public class MPArray<T extends MPType> implements MPType<List<T>> {
         return Objects.hash(array);
     }
 
+    @Override
+    public T get(int i) {
+        return array.get(i);
+    }
+
+    @Override
+    public T set(int i, T t) {
+        return array.set(i, t);
+    }
+
+    @Override
+    public void add(int i, T t) {
+        array.add(i, t);
+    }
+
+    @Override
+    public T remove(int i) {
+        return array.remove(i);
+    }
+
+    @Override
+    public int indexOf(Object o) {
+        return array.indexOf(o);
+    }
+
+    @Override
+    public int lastIndexOf(Object o) {
+        return array.lastIndexOf(o);
+    }
+
+    @Override
+    public ListIterator<T> listIterator() {
+        return array.listIterator();
+    }
+
+    @Override
+    public ListIterator<T> listIterator(int i) {
+        return array.listIterator(i);
+    }
+
+    @Override
+    public List<T> subList(int fromIndex, int toIndex) {
+        return array.subList(fromIndex, toIndex);
+    }
+
     @Override
     public String toString() {
         StringBuilder result = new StringBuilder();

src/main/java/ch/dissem/msgpack/types/MPBinary.java

@@ -8,6 +8,9 @@ import java.util.Arrays;
 
 import static ch.dissem.msgpack.types.Utils.bytes;
 
+/**
+ * Representation of msgpack encoded binary data a.k.a. byte array.
+ */
 public class MPBinary implements MPType<byte[]> {
     private byte[] value;
 

src/main/java/ch/dissem/msgpack/types/MPBoolean.java

@@ -5,6 +5,9 @@ import java.io.InputStream;
 import java.io.OutputStream;
 import java.util.Objects;
 
+/**
+ * Representation of a msgpack encoded boolean.
+ */
 public class MPBoolean implements MPType<Boolean> {
     private final static int FALSE = 0xC2;
     private final static int TRUE = 0xC3;

src/main/java/ch/dissem/msgpack/types/MPDouble.java

@@ -8,6 +8,9 @@ import java.util.Objects;
 
 import static ch.dissem.msgpack.types.Utils.bytes;
 
+/**
+ * Representation of a msgpack encoded float64 number.
+ */
 public class MPDouble implements MPType<Double> {
     private double value;
 

src/main/java/ch/dissem/msgpack/types/MPFloat.java

@@ -8,6 +8,9 @@ import java.util.Objects;
 
 import static ch.dissem.msgpack.types.Utils.bytes;
 
+/**
+ * Representation of a msgpack encoded float32 number.
+ */
 public class MPFloat implements MPType<Float> {
     private float value;
 

src/main/java/ch/dissem/msgpack/types/MPInteger.java

@@ -8,6 +8,12 @@ import java.util.Objects;
 
 import static ch.dissem.msgpack.types.Utils.bytes;
 
+/**
+ * Representation of a msgpack encoded integer. The encoding is automatically selected according to the value's size.
+ * Uses long due to the fact that the msgpack integer implementation may contain up to 64 bit numbers, corresponding
+ * to Java long values. Also note that uint64 values may be too large for signed long (thanks Java for not supporting
+ * unsigned values) and end in a negative value.
+ */
 public class MPInteger implements MPType<Long> {
     private long value;
 

src/main/java/ch/dissem/msgpack/types/MPMap.java

@@ -6,14 +6,22 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.nio.ByteBuffer;
-import java.util.Iterator;
-import java.util.LinkedHashMap;
-import java.util.Map;
-import java.util.Objects;
+import java.util.*;
 
-public class MPMap<K extends MPType, V extends MPType> implements MPType<Map<K, V>> {
+/**
+ * Representation of a msgpack encoded map. It is recommended to use a {@link LinkedHashMap} to ensure the order
+ * of entries. For convenience, it also implements the {@link Map} interface.
+ *
+ * @param <K>
+ * @param <V>
+ */
+public class MPMap<K extends MPType, V extends MPType> implements MPType<Map<K, V>>, Map<K, V> {
     private Map<K, V> map;
 
+    public MPMap() {
+        this.map = new LinkedHashMap<>();
+    }
+
     public MPMap(Map<K, V> map) {
         this.map = map;
     }
@@ -40,6 +48,66 @@ public class MPMap<K extends MPType, V extends MPType> implements MPType<Map<K,
         }
     }
 
+    @Override
+    public int size() {
+        return map.size();
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return map.isEmpty();
+    }
+
+    @Override
+    public boolean containsKey(Object o) {
+        return map.containsKey(o);
+    }
+
+    @Override
+    public boolean containsValue(Object o) {
+        return map.containsValue(o);
+    }
+
+    @Override
+    public V get(Object o) {
+        return map.get(o);
+    }
+
+    @Override
+    public V put(K k, V v) {
+        return map.put(k, v);
+    }
+
+    @Override
+    public V remove(Object o) {
+        return map.remove(o);
+    }
+
+    @Override
+    public void putAll(Map<? extends K, ? extends V> map) {
+        this.map.putAll(map);
+    }
+
+    @Override
+    public void clear() {
+        map.clear();
+    }
+
+    @Override
+    public Set<K> keySet() {
+        return map.keySet();
+    }
+
+    @Override
+    public Collection<V> values() {
+        return map.values();
+    }
+
+    @Override
+    public Set<Entry<K, V>> entrySet() {
+        return map.entrySet();
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;

src/main/java/ch/dissem/msgpack/types/MPNil.java

@@ -4,6 +4,9 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 
+/**
+ * Representation of msgpack encoded nil / null.
+ */
 public class MPNil implements MPType<Void> {
     private final static int NIL = 0xC0;
 
@@ -27,7 +30,7 @@ public class MPNil implements MPType<Void> {
 
     @Override
     public String toString() {
-        return "nil";
+        return "null";
     }
 
     public static class Unpacker implements MPType.Unpacker<MPNil> {

src/main/java/ch/dissem/msgpack/types/MPString.java

@@ -4,12 +4,42 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.nio.ByteBuffer;
+import java.nio.charset.Charset;
 import java.util.Objects;
 
 import static ch.dissem.msgpack.types.Utils.bytes;
 
-public class MPString implements MPType<String> {
-    private String value;
+/**
+ * Representation of a msgpack encoded string. The encoding is automatically selected according to the string's length.
+ * <p>
+ * The default encoding is UTF-8.
+ * </p>
+ */
+public class MPString implements MPType<String>, CharSequence {
+    private static final int FIXSTR_PREFIX = 0b10100000;
+    private static final int FIXSTR_PREFIX_FILTER = 0b11100000;
+    private static final int STR8_PREFIX = 0xD9;
+    private static final int STR8_LIMIT = 256;
+    private static final int STR16_PREFIX = 0xDA;
+    private static final int STR16_LIMIT = 65536;
+    private static final int STR32_PREFIX = 0xDB;
+    private static final int FIXSTR_FILTER = 0b00011111;
+
+    private static Charset encoding = Charset.forName("UTF-8");
+
+    /**
+     * Use this method if for some messed up reason you really need to use something else than UTF-8.
+     * Ask yourself: why should I? Is this really necessary?
+     * <p>
+     * It will set the encoding for all {@link MPString}s, but if you have inconsistent encoding in your
+     * format you're lost anyway.
+     * </p>
+     */
+    public static void setEncoding(Charset encoding) {
+        MPString.encoding = encoding;
+    }
+
+    private final String value;
 
     public MPString(String value) {
         this.value = value;
@@ -22,18 +52,18 @@ public class MPString implements MPType<String> {
     public void pack(OutputStream out) throws IOException {
         int size = value.length();
         if (size < 32) {
-            out.write(0b10100000 + size);
-        } else if (size < 256) {
-            out.write(0xD9);
+            out.write(FIXSTR_PREFIX + size);
+        } else if (size < STR8_LIMIT) {
+            out.write(STR8_PREFIX);
             out.write(size);
-        } else if (size < 65536) {
-            out.write(0xDA);
+        } else if (size < STR16_LIMIT) {
+            out.write(STR16_PREFIX);
             out.write(ByteBuffer.allocate(2).putShort((short) size).array());
         } else {
-            out.write(0xDB);
+            out.write(STR32_PREFIX);
             out.write(ByteBuffer.allocate(4).putInt(size).array());
         }
-        out.write(value.getBytes("UTF-8"));
+        out.write(value.getBytes(encoding));
     }
 
     @Override
@@ -49,30 +79,46 @@ public class MPString implements MPType<String> {
         return Objects.hash(value);
     }
 
+    @Override
+    public int length() {
+        return value.length();
+    }
+
+    @Override
+    public char charAt(int i) {
+        return value.charAt(i);
+    }
+
+    @Override
+    public CharSequence subSequence(int beginIndex, int endIndex) {
+        return value.subSequence(beginIndex, endIndex);
+    }
+
     @Override
     public String toString() {
-        return '"' + value + '"'; // FIXME: escape value
+        return value;
     }
 
     public static class Unpacker implements MPType.Unpacker<MPString> {
         public boolean is(int firstByte) {
-            return firstByte == 0xD9 || firstByte == 0xDA || firstByte == 0xDB || (firstByte & 0b11100000) == 0b10100000;
+            return firstByte == STR8_PREFIX || firstByte == STR16_PREFIX || firstByte == STR32_PREFIX
+                    || (firstByte & FIXSTR_PREFIX_FILTER) == FIXSTR_PREFIX;
         }
 
         public MPString unpack(int firstByte, InputStream in) throws IOException {
             int size;
-            if ((firstByte & 0b11100000) == 0b10100000) {
-                size = firstByte & 0b00011111;
-            } else if (firstByte == 0xD9) {
+            if ((firstByte & FIXSTR_PREFIX_FILTER) == FIXSTR_PREFIX) {
+                size = firstByte & FIXSTR_FILTER;
+            } else if (firstByte == STR8_PREFIX) {
                 size = in.read();
-            } else if (firstByte == 0xDA) {
+            } else if (firstByte == STR16_PREFIX) {
                 size = in.read() << 8 | in.read();
-            } else if (firstByte == 0xDB) {
+            } else if (firstByte == STR32_PREFIX) {
                 size = in.read() << 24 | in.read() << 16 | in.read() << 8 | in.read();
             } else {
                 throw new IllegalArgumentException(String.format("Unexpected first byte 0x%02x", firstByte));
             }
-            return new MPString(new String(bytes(in, size).array(), "UTF-8"));
+            return new MPString(new String(bytes(in, size).array(), encoding));
         }
     }
 }

src/main/java/ch/dissem/msgpack/types/MPType.java

@@ -5,7 +5,7 @@ import java.io.InputStream;
 import java.io.OutputStream;
 
 /**
- * Representation for some msgpack encoded data.
+ * Representation of some msgpack encoded data.
  */
 public interface MPType<T> {
     interface Unpacker<M extends MPType> {

src/main/java/ch/dissem/msgpack/types/Utils.java

@@ -5,6 +5,9 @@ import java.io.InputStream;
 import java.nio.ByteBuffer;
 
 class Utils {
+    /**
+     * Returns a {@link ByteBuffer} containing the next <code>count</code> bytes from the {@link InputStream}.
+     */
     static ByteBuffer bytes(InputStream in, int count) throws IOException {
         byte[] result = new byte[count];
         int off = 0;

src/test/java/ch/dissem/msgpack/ReaderTest.java

@@ -29,9 +29,9 @@ public class ReaderTest {
 
     @Test
     public void ensureDemoJsonIsEncodedCorrectly() throws Exception {
-        MPMap<MPString, MPType<?>> object = new MPMap<>(new LinkedHashMap<MPString, MPType<?>>());
-        object.getValue().put(new MPString("compact"), new MPBoolean(true));
-        object.getValue().put(new MPString("schema"), new MPInteger(0));
+        MPMap<MPString, MPType<?>> object = new MPMap<>();
+        object.put(new MPString("compact"), new MPBoolean(true));
+        object.put(new MPString("schema"), new MPInteger(0));
         ByteArrayOutputStream out = new ByteArrayOutputStream();
         object.pack(out);
         assertThat(out.toByteArray(), is(bytes("demo.mp")));