JSON Format Conversion

/**
 * Creates a Printer with default configurations.
 * 
 * @return A new Printer instance with default settings
 */
public static JsonFormat.Printer printer();

/**
 * Creates a Parser with default configuration.
 * 
 * @return A new Parser instance with default settings
 */
public static JsonFormat.Parser parser();

/**
 * Creates a new Printer using the given registry for resolving Any types.
 * 
 * @param registry TypeRegistry for resolving Any message types
 * @return New Printer with the specified type registry
 * @throws IllegalArgumentException if a registry is already set
 */
public JsonFormat.Printer usingTypeRegistry(JsonFormat.TypeRegistry registry);

/**
 * Creates a new Printer using the given registry for resolving Any types.
 * 
 * @param registry com.google.protobuf.TypeRegistry for resolving Any message types
 * @return New Printer with the specified type registry
 * @throws IllegalArgumentException if a registry is already set
 */
public JsonFormat.Printer usingTypeRegistry(com.google.protobuf.TypeRegistry registry);

/**
 * Creates a new Printer that will always print fields unless they are a message type or in a oneof.
 * Note: This method is deprecated.
 * 
 * @return New Printer that includes default value fields
 * @deprecated Use alwaysPrintFieldsWithNoPresence() instead
 */
@Deprecated
public JsonFormat.Printer includingDefaultValueFields();

/**
 * Creates a new Printer that will print specified default-valued fields.
 * 
 * @param fieldsToAlwaysOutput Set of field descriptors to always print
 * @return New Printer with specified default field behavior
 */
public JsonFormat.Printer includingDefaultValueFields(Set<FieldDescriptor> fieldsToAlwaysOutput);

/**
 * Creates a new Printer that prints fields with no presence even if default.
 * 
 * @return New Printer that prints fields without presence
 */
public JsonFormat.Printer alwaysPrintFieldsWithNoPresence();

/**
 * Creates a new Printer that prints enum field values as integers.
 * 
 * @return New Printer that prints enums as integers
 */
public JsonFormat.Printer printingEnumsAsInts();

/**
 * Creates a new Printer that uses original proto field names instead of camelCase.
 * 
 * @return New Printer that preserves proto field names
 */
public JsonFormat.Printer preservingProtoFieldNames();

/**
 * Creates a new Printer that omits insignificant whitespace in JSON output.
 * 
 * @return New Printer that produces compact JSON
 */
public JsonFormat.Printer omittingInsignificantWhitespace();

/**
 * Creates a new Printer that sorts map keys in JSON output.
 * 
 * @return New Printer that sorts map keys
 */
public JsonFormat.Printer sortingMapKeys();

/**
 * Converts a protobuf message to Proto3 JSON format.
 * 
 * @param message The protobuf message to convert
 * @param output The output destination for JSON
 * @throws InvalidProtocolBufferException if message contains unresolvable Any types
 * @throws IOException if writing to output fails
 */
public void appendTo(MessageOrBuilder message, Appendable output) throws IOException;

/**
 * Converts a protobuf message to Proto3 JSON format as a string.
 * 
 * @param message The protobuf message to convert
 * @return JSON string representation of the message
 * @throws InvalidProtocolBufferException if message contains unresolvable Any types
 */
public String print(MessageOrBuilder message) throws InvalidProtocolBufferException;

/**
 * Creates a new Parser using the given registry for resolving Any types.
 * 
 * @param registry TypeRegistry for resolving Any message types
 * @return New Parser with the specified type registry
 * @throws IllegalArgumentException if a registry is already set
 */
public JsonFormat.Parser usingTypeRegistry(JsonFormat.TypeRegistry registry);

/**
 * Creates a new Parser using the given registry for resolving Any types.
 * 
 * @param registry com.google.protobuf.TypeRegistry for resolving Any message types
 * @return New Parser with the specified type registry
 * @throws IllegalArgumentException if a registry is already set
 */
public JsonFormat.Parser usingTypeRegistry(com.google.protobuf.TypeRegistry registry);

/**
 * Creates a new Parser that ignores unknown fields instead of throwing exceptions.
 * 
 * @return New Parser that ignores unknown fields
 */
public JsonFormat.Parser ignoringUnknownFields();

/**
 * Parses Proto3 JSON format into a protobuf message.
 * 
 * @param json JSON string to parse
 * @param builder Message builder to populate
 * @throws InvalidProtocolBufferException if JSON is invalid or contains unknown fields
 */
public void merge(String json, Message.Builder builder) throws InvalidProtocolBufferException;

/**
 * Parses Proto3 JSON from a Reader into a protobuf message.
 * 
 * @param json Reader containing JSON data
 * @param builder Message builder to populate
 * @throws InvalidProtocolBufferException if JSON is invalid or contains unknown fields
 * @throws IOException if reading from input fails
 */
public void merge(Reader json, Message.Builder builder) throws IOException;

/**
 * Returns an empty TypeRegistry.
 * 
 * @return Empty TypeRegistry instance
 */
public static JsonFormat.TypeRegistry getEmptyTypeRegistry();

/**
 * Creates a new TypeRegistry builder.
 * 
 * @return New TypeRegistry.Builder instance
 */
public static JsonFormat.TypeRegistry.Builder newBuilder();

/**
 * Finds a type by its full name.
 * 
 * @param name Full name of the message type
 * @return Descriptor for the type, or null if not found
 */
public Descriptor find(String name);

/**
 * Adds a message type and all transitively imported types to the registry.
 * 
 * @param messageType Message descriptor to add
 * @return This builder for method chaining
 */
public JsonFormat.TypeRegistry.Builder add(Descriptor messageType);

/**
 * Adds multiple message types and all transitively imported types to the registry.
 * 
 * @param messageTypes Iterable of message descriptors to add
 * @return This builder for method chaining
 */
public JsonFormat.TypeRegistry.Builder add(Iterable<Descriptor> messageTypes);

/**
 * Builds the TypeRegistry.
 * 
 * @return New TypeRegistry instance
 */
public JsonFormat.TypeRegistry build();

import com.google.protobuf.util.JsonFormat;
import com.google.protobuf.InvalidProtocolBufferException;

// Basic JSON conversion
JsonFormat.Printer printer = JsonFormat.printer();
String jsonString = printer.print(myMessage);

JsonFormat.Parser parser = JsonFormat.parser();
MyMessage.Builder builder = MyMessage.newBuilder();
parser.merge(jsonString, builder);
MyMessage parsed = builder.build();

// Custom printer configuration
JsonFormat.Printer customPrinter = JsonFormat.printer()
    .preservingProtoFieldNames()
    .omittingInsignificantWhitespace()
    .printingEnumsAsInts();

String compactJson = customPrinter.print(myMessage);

// Parser with unknown field handling
JsonFormat.Parser tolerantParser = JsonFormat.parser()
    .ignoringUnknownFields();

MyMessage.Builder tolerantBuilder = MyMessage.newBuilder();
tolerantParser.merge(jsonWithExtraFields, tolerantBuilder);

// Type registry for Any types
JsonFormat.TypeRegistry typeRegistry = JsonFormat.TypeRegistry.newBuilder()
    .add(MyCustomMessage.getDescriptor())
    .add(AnotherMessage.getDescriptor())
    .build();

JsonFormat.Printer anyPrinter = JsonFormat.printer()
    .usingTypeRegistry(typeRegistry);

JsonFormat.Parser anyParser = JsonFormat.parser()
    .usingTypeRegistry(typeRegistry);