Gson

Constructs a Gson object with default configuration. The default configuration has the following settings:

• The JSON generated by toJson methods is in compact representation. This means that all the unneeded white-space is removed. You can change this behavior with setPrettyPrinting().
• The generated JSON omits all the fields that are null. Note that nulls in arrays are kept as is since an array is an ordered list. Moreover, if a field is not null, but its generated JSON is empty, the field is kept. You can configure Gson to serialize null values by setting serializeNulls().
• Gson provides default serialization and deserialization for Enums, Map, java.net.URL, java.net.URI, java.util.Locale, java.util.Date, java.math.BigDecimal, and java.math.BigInteger classes. If you would prefer to change the default representation, you can do so by registering a type adapter through registerTypeAdapter(Type, Object).
• The default Date format is same as DEFAULT. This format ignores the millisecond portion of the date during serialization. You can change this by invoking setDateFormat(int) or setDateFormat(String).
• By default, Gson ignores the com.google.gson.annotations.Expose annotation. You can enable Gson to serialize/deserialize only those fields marked with this annotation through excludeFieldsWithoutExposeAnnotation().
• By default, Gson ignores the com.google.gson.annotations.Since annotation. You can enable Gson to use this annotation through setVersion(double).
• The default field naming policy for the output Json is same as in Java. So, a Java class field versionNumber will be output as "versionNumber@quot; in Json. The same rules are applied for mapping incoming Json to the Java classes. You can change this policy through setFieldNamingPolicy(FieldNamingPolicy).
• By default, Gson excludes transient or static fields from consideration for serialization and deserialization. You can change this behavior through excludeFieldsWithModifiers(int).

This method deserializes the specified Json into an object of the specified class. It is not suitable to use if the specified class is a generic type since it will not have the generic type information because of the Type Erasure feature of Java. Therefore, this method should not be used if the desired type is a generic type. Note that this method works fine if the any of the fields of the specified object are generics, just the object itself should not be a generic type. For the cases when the object is of generic type, invoke fromJson(String, Type). If you have the Json in a Reader instead of a String, use fromJson(Reader, Class) instead.

This method deserializes the Json read from the specified parse tree into an object of the specified type. This method is useful if the specified object is a generic type. For non-generic objects, use fromJson(JsonElement, Class) instead.

This method deserializes the Json read from the specified parse tree into an object of the specified type. It is not suitable to use if the specified class is a generic type since it will not have the generic type information because of the Type Erasure feature of Java. Therefore, this method should not be used if the desired type is a generic type. Note that this method works fine if the any of the fields of the specified object are generics, just the object itself should not be a generic type. For the cases when the object is of generic type, invoke fromJson(JsonElement, Type).

This method deserializes the Json read from the specified reader into an object of the specified class. It is not suitable to use if the specified class is a generic type since it will not have the generic type information because of the Type Erasure feature of Java. Therefore, this method should not be used if the desired type is a generic type. Note that this method works fine if the any of the fields of the specified object are generics, just the object itself should not be a generic type. For the cases when the object is of generic type, invoke fromJson(Reader, Type). If you have the Json in a String form instead of a Reader, use fromJson(String, Class) instead.

This method deserializes the specified Json into an object of the specified type. This method is useful if the specified object is a generic type. For non-generic objects, use fromJson(String, Class) instead. If you have the Json in a Reader instead of a String, use fromJson(Reader, Type) instead.

This method deserializes the Json read from the specified reader into an object of the specified type. This method is useful if the specified object is a generic type. For non-generic objects, use fromJson(Reader, Class) instead. If you have the Json in a String form instead of a Reader, use fromJson(String, Type) instead.

Reads the next JSON value from reader and convert it to an object of type typeOfT. Since Type is not parameterized by T, this method is type unsafe and should be used carefully

Returns the type adapter for type.

Returns the type adapter for type.

This method is used to get an alternate type adapter for the specified type. This is used to access a type adapter that is overridden by a TypeAdapterFactory that you may have registered. This features is typically used when you want to register a type adapter that does a little bit of work but then delegates further processing to the Gson default type adapter. Here is an example:

Let's say we want to write a type adapter that counts the number of objects being read from or written to JSON. We can achieve this by writing a type adapter factory that uses the getDelegateAdapter method:

 class StatsTypeAdapterFactory implements TypeAdapterFactory {
    public int numReads = 0;
    public int numWrites = 0;
    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
      final TypeAdapter<T> delegate = gson.getDelegateAdapter(this, type);
      return new TypeAdapter<T>() {
        public void write(JsonWriter out, T value) throws IOException {
          ++numWrites;
          delegate.write(out, value);
        
        public T read(JsonReader in) throws IOException {
          ++numReads;
          return delegate.read(in);
        }
      };
    }
  }
  } 

 StatsTypeAdapterFactory stats = new StatsTypeAdapterFactory();
  Gson gson = new GsonBuilder().registerTypeAdapterFactory(stats).create();
  // Call gson.toJson() and fromJson methods on objects
  System.out.println("Num JSON reads" + stats.numReads);
  System.out.println("Num JSON writes" + stats.numWrites);
  

Writes the JSON representation of src of type typeOfSrc to writer.

Writes out the equivalent JSON for a tree of JsonElements.

Writes the JSON for jsonElement to writer.

Converts a tree of JsonElements into its equivalent JSON representation.

This method serializes the specified object into its equivalent Json representation. This method should be used when the specified object is not a generic type. This method uses getClass() to get the type for the specified object, but the getClass() loses the generic type information because of the Type Erasure feature of Java. Note that this method works fine if the any of the object fields are of generic type, just the object itself should not be of a generic type. If the object is of generic type, use toJson(Object, Type) instead. If you want to write out the object to a Writer, use toJson(Object, Appendable) instead.

This method serializes the specified object into its equivalent Json representation. This method should be used when the specified object is not a generic type. This method uses getClass() to get the type for the specified object, but the getClass() loses the generic type information because of the Type Erasure feature of Java. Note that this method works fine if the any of the object fields are of generic type, just the object itself should not be of a generic type. If the object is of generic type, use toJson(Object, Type, Appendable) instead.

This method serializes the specified object, including those of generic types, into its equivalent Json representation. This method must be used if the specified object is a generic type. For non-generic objects, use toJson(Object) instead. If you want to write out the object to a Appendable, use toJson(Object, Type, Appendable) instead.

This method serializes the specified object, including those of generic types, into its equivalent Json representation. This method must be used if the specified object is a generic type. For non-generic objects, use toJson(Object, Appendable) instead.

This method serializes the specified object into its equivalent representation as a tree of JsonElements. This method should be used when the specified object is not a generic type. This method uses getClass() to get the type for the specified object, but the getClass() loses the generic type information because of the Type Erasure feature of Java. Note that this method works fine if the any of the object fields are of generic type, just the object itself should not be of a generic type. If the object is of generic type, use toJsonTree(Object, Type) instead.

This method serializes the specified object, including those of generic types, into its equivalent representation as a tree of JsonElements. This method must be used if the specified object is a generic type. For non-generic objects, use toJsonTree(Object) instead.