Next, create handler methods for each structure in your JSON text. You'll need a method for each object type and for each array type.
When a nested object or array is encountered, delegate to the corresponding handler method.
When an unknown name is encountered, strict parsers should fail with an exception. Lenient parsers should call {@link #skipValue()} to recursivelyskip the value's nested tokens, which may otherwise conflict.
If a value may be null, you should first check using {@link #peek()}. Null literals can be consumed using either {@link #nextNull()} or {@link #skipValue()}.
{@code [}{ "id": 912345678901, "text": "How do I read a JSON stream in Java?", "geo": null, "user": { "name": "json_newb", "followers_count": 41 } }, { "id": 912345678902, "text": "@json_newb just use JsonReader!", "geo": [50.454722, -104.606667], "user": { "name": "jesse", "followers_count": 2 } } ]}This code implements the parser for the above structure:
{@code}public ListreadJsonStream(InputStream in) throws IOException JsonReader reader = new JsonReader(new InputStreamReader(in, "UTF-8")); try { return readMessagesArray(reader); } finally { reader.close(); } } public List readMessagesArray(JsonReader reader) throws IOException { List messages = new ArrayList (); reader.beginArray(); while (reader.hasNext()) { messages.add(readMessage(reader)); } reader.endArray(); return messages; } public Message readMessage(JsonReader reader) throws IOException { long id = -1; String text = null; User user = null; List geo = null; reader.beginObject(); while (reader.hasNext()) { String name = reader.nextName(); if (name.equals("id")) { id = reader.nextLong(); } else if (name.equals("text")) { text = reader.nextString(); } else if (name.equals("geo") && reader.peek() != JsonToken.NULL) { geo = readDoublesArray(reader); } else if (name.equals("user")) { user = readUser(reader); } else { reader.skipValue(); } } reader.endObject(); return new Message(id, text, user, geo); } public List readDoublesArray(JsonReader reader) throws IOException { List doubles = new ArrayList (); reader.beginArray(); while (reader.hasNext()) { doubles.add(reader.nextDouble()); } reader.endArray(); return doubles; } public User readUser(JsonReader reader) throws IOException { String username = null; int followersCount = -1; reader.beginObject(); while (reader.hasNext()) { String name = reader.nextName(); if (name.equals("name")) { username = reader.nextString(); } else if (name.equals("followers_count")) { followersCount = reader.nextInt(); } else { reader.skipValue(); } } reader.endObject(); return new User(username, followersCount); }}