JsonWriter

Kotlin |Java

class JsonWriter : Closeable

kotlin.Any
↳	android.util.JsonWriter

Writes a JSON (RFC 4627) encoded value to a stream, one token at a time. The stream includes both literal values (strings, numbers, booleans and nulls) as well as the begin and end delimiters of objects and arrays.

Encoding JSON

To encode your data as JSON, create a new JsonWriter. Each JSON document must contain one top-level array or object. Call methods on the writer as you walk the structure's contents, nesting arrays and objects as necessary:

To write arrays, first call beginArray(). Write each of the array's elements with the appropriate #value methods or by nesting other arrays and objects. Finally close the array using endArray().
To write objects, first call beginObject(). Write each of the object's properties by alternating calls to name with the property's value. Write property values with the appropriate #value method or by nesting other objects or arrays. Finally close the object using endObject().

Example

Suppose we'd like to encode a stream of messages such as the following:

<code>[
    {
      "id": 912345678901,
      "text": "How do I write JSON on Android?",
      "geo": null,
      "user": {
        "name": "android_newb",
        "followers_count": 41
       }
    },
    {
      "id": 912345678902,
      "text": "@android_newb just use android.util.JsonWriter!",
      "geo": [50.454722, -104.606667],
      "user": {
        "name": "jesse",
        "followers_count": 2
      }
    }
  ]</code>

This code encodes the above structure:

<code>public void writeJsonStream(OutputStream out, List&lt;Message&gt; messages) throws IOException {
      JsonWriter writer = new JsonWriter(new OutputStreamWriter(out, "UTF-8"));
      writer.setIndent("  ");
      writeMessagesArray(writer, messages);
      writer.close();
    }
 
    public void writeMessagesArray(JsonWriter writer, List&lt;Message&gt; messages) throws IOException {
      writer.beginArray();
      for (Message message : messages) {
        writeMessage(writer, message);
      }
      writer.endArray();
    }
 
    public void writeMessage(JsonWriter writer, Message message) throws IOException {
      writer.beginObject();
      writer.name("id").value(message.getId());
      writer.name("text").value(message.getText());
      if (message.getGeo() != null) {
        writer.name("geo");
        writeDoublesArray(writer, message.getGeo());
      } else {
        writer.name("geo").nullValue();
      }
      writer.name("user");
      writeUser(writer, message.getUser());
      writer.endObject();
    }
 
    public void writeUser(JsonWriter writer, User user) throws IOException {
      writer.beginObject();
      writer.name("name").value(user.getName());
      writer.name("followers_count").value(user.getFollowersCount());
      writer.endObject();
    }
 
    public void writeDoublesArray(JsonWriter writer, List&lt;Double&gt; doubles) throws IOException {
      writer.beginArray();
      for (Double value : doubles) {
        writer.value(value);
      }
      writer.endArray();
    }</code>

Each JsonWriter may be used to write a single JSON stream. Instances of this class are not thread safe. Calls that would result in a malformed JSON string will fail with an IllegalStateException.

Summary

Public constructors
`JsonWriter(out: Writer!)` Creates a new instance that writes a JSON-encoded stream to `out`.

Public methods
JsonWriter!	`beginArray()` Begins encoding a new array.
JsonWriter!	`beginObject()` Begins encoding a new object.
Unit	`close()` Flushes and closes this writer and the underlying `Writer`.
JsonWriter!	`endArray()` Ends encoding the current array.
JsonWriter!	`endObject()` Ends encoding the current object.
Unit	`flush()` Ensures all buffered data is written to the underlying `Writer` and flushes that writer.
Boolean	`isLenient()` Returns true if this writer has relaxed syntax rules.
JsonWriter!	`name(name: String!)` Encodes the property name.
JsonWriter!	`nullValue()` Encodes `null`.
Unit	`setIndent(indent: String!)` Sets the indentation string to be repeated for each level of indentation in the encoded document.
Unit	`setLenient(lenient: Boolean)` Configure this writer to relax its syntax rules.
JsonWriter!	`value(value: String!)` Encodes `value`.
JsonWriter!	`value(value: Boolean)` Encodes `value`.
JsonWriter!	`value(value: Double)` Encodes `value`.
JsonWriter!	`value(value: Long)` Encodes `value`.
JsonWriter!	`value(value: Number!)` Encodes `value`.

Exceptions
`java.lang.Exception`	if this resource cannot be closed
`java.io.IOException`	if the JSON document is incomplete.

JsonWriter

Encoding JSON

Example

Summary

Public constructors

JsonWriter

Public methods

beginArray

beginObject

close

endArray

endObject

flush

isLenient

name

nullValue

setIndent

setLenient

value

value

value

value

value