Add comments, fix nits

moshi/src/main/java/com/squareup/moshi/JsonReader.java

@@ -899,7 +899,7 @@ public class JsonReader implements Closeable {
     peeked = PEEKED_BUFFERED;
     double result = Double.parseDouble(peekedString); // don't catch this NumberFormatException.
     if (!lenient && (Double.isNaN(result) || Double.isInfinite(result))) {
-      throw new IOException("JSON forbids NaN and infinities: " + result
+      throw new NumberFormatException("JSON forbids NaN and infinities: " + result
           + " at path " + getPath());
     }
     peekedString = null;

moshi/src/main/java/com/squareup/moshi/StandardJsonAdapters.java

@@ -103,18 +103,20 @@ final class StandardJsonAdapters {
   static final JsonAdapter<Float> FLOAT_JSON_ADAPTER = new JsonAdapter<Float>() {
     @Override public Float fromJson(JsonReader reader) throws IOException {
       float value = (float) reader.nextDouble();
+      // Double check for infinity after float conversion; many doubles > Float.MAX
       if (!reader.isLenient() && Float.isInfinite(value)) {
-        throw new IOException("JSON forbids NaN and infinities: " + value
+        throw new NumberFormatException("JSON forbids NaN and infinities: " + value
             + " at path " + reader.getPath());
       }
       return value;
     }
 
     @Override public void toJson(JsonWriter writer, Float value) throws IOException {
-      // Use the Number overload.
+      // Manual null pointer check for the float.class adapter.
       if (value == null) {
         throw new NullPointerException();
       }
+      // Use the Number overload so we write out float precision instead of double precision.
       writer.value(value);
     }
   };

moshi/src/test/java/com/squareup/moshi/MoshiTest.java

@@ -269,8 +269,7 @@ public final class MoshiTest {
     try {
       adapter.fromJson(reader);
       fail();
-    } catch (IOException expected) {
-      // TODO: should this really be NumberFormatException?
+    } catch (NumberFormatException expected) {
       assertThat(expected.getMessage()).isEqualTo("JSON forbids NaN and infinities: Infinity at path $[0]");
     }
 
@@ -279,8 +278,7 @@ public final class MoshiTest {
     try {
       adapter.fromJson(reader);
       fail();
-    } catch (IOException expected) {
-      // TODO: should this really be NumberFormatException?
+    } catch (NumberFormatException expected) {
       assertThat(expected.getMessage()).isEqualTo("JSON forbids NaN and infinities: -Infinity at path $[0]");
     }
   }
@@ -339,8 +337,7 @@ public final class MoshiTest {
     try {
       adapter.fromJson(reader);
       fail();
-    } catch (IOException expected) {
-      // TODO: should this really be NumberFormatException?
+    } catch (NumberFormatException expected) {
       assertThat(expected.getMessage()).isEqualTo("JSON forbids NaN and infinities: Infinity at path $[1]");
     }
 
@@ -349,8 +346,7 @@ public final class MoshiTest {
     try {
       adapter.fromJson(reader);
       fail();
-    } catch (IOException expected) {
-      // TODO: should this really be NumberFormatException?
+    } catch (NumberFormatException expected) {
       assertThat(expected.getMessage()).isEqualTo("JSON forbids NaN and infinities: -Infinity at path $[1]");
     }
   }