Package processing.data

Class JSONObject

java.lang.Object
processing.data.JSONObject
public class JSONObject extends Object
A JSONObject stores JSON data with multiple name/value pairs. Values can be numeric, Strings, booleans, other JSONObjects or JSONArrays, or null. JSONObject and JSONArray objects are quite similar and share most of the same methods; the primary difference is that the latter stores an array of JSON objects, while the former represents a single JSON object.

JSON can be generated from scratch, dynamically, or using data from an existing file. JSON can also be output and saved to disk, as in the example above.

Advanced

A JSONObject is an unordered collection of name/value pairs. Its external form is a string wrapped in curly braces with colons between the names and values, and commas between the values and names. The internal form is an object having get and opt methods for accessing the values by name, and put methods for adding or replacing values by name. The values can be any of these types: Boolean, JSONArray, JSONObject, Number, String, or the JSONObject.NULL object. A JSONObject constructor can be used to convert an external form JSON text into an internal form whose values can be retrieved with the get and opt methods, or to convert values into a JSON text using the put and toString methods. A get method returns a value if one can be found, and throws an exception if one cannot be found. An opt method returns a default value instead of throwing an exception, and so is useful for obtaining optional values.

The generic get() and opt() methods return an object, which you can cast or query for type. There are also typed get and opt methods that do type checking and type coercion for you. The opt methods differ from the get methods in that they do not throw. Instead, they return a specified value, such as null.

The put methods add or replace values in an object. For example, 

 myString = new JSONObject().put("JSON", "Hello, World!").toString();
produces the string {"JSON": "Hello, World"}.

The texts produced by the toString methods strictly conform to the JSON syntax rules. The constructors are more forgiving in the texts they will accept:

  • An extra , (comma) may appear just before the closing brace.
  • Strings may be quoted with ' (single quote).
  • Strings do not need to be quoted at all if they do not begin with a quote or single quote, and if they do not contain leading or trailing spaces, and if they do not contain any of these characters: { } [ ] / \ : , = ; # and if they do not look like numbers and if they are not the reserved words true, false, or null.
  • Keys can be followed by = or => as well as by :.
  • Values can be followed by ; (semicolon) as well as by , (comma).
See Also:

  • Field Details

    • NULL

      public static final Object NULL
      It is sometimes more convenient and less ambiguous to have a NULL object than to use Java's null value. JSONObject.NULL.equals(null) returns true. JSONObject.NULL.toString() returns "null".

  • Constructor Details

    • JSONObject

      public JSONObject()
      Construct an empty JSONObject.

    • JSONObject

      public JSONObject(Reader reader)

    • JSONObject

      protected JSONObject(processing.data.JSONTokener x)
      Construct a JSONObject from a JSONTokener.
      Parameters:
      x - A JSONTokener object containing the source string.
      Throws:
      RuntimeException - If there is a syntax error in the source string or a duplicated key.

    • JSONObject

      protected JSONObject(HashMap<String,Object> map)
      Construct a JSONObject from a Map.
      Parameters:
      map - A map object that can be used to initialize the contents of the JSONObject.

    • JSONObject

      public JSONObject(IntDict dict)

    • JSONObject

      public JSONObject(FloatDict dict)

    • JSONObject

      public JSONObject(StringDict dict)

    • JSONObject

      protected JSONObject(Object bean)
      Construct a JSONObject from an Object using bean getters. It reflects on all of the public methods of the object. For each of the methods with no parameters and a name starting with "get" or "is" followed by an uppercase letter, the method is invoked, and a key and the value returned from the getter method are put into the new JSONObject. The key is formed by removing the "get" or "is" prefix. If the second remaining character is not upper case, then the first character is converted to lower case. For example, if an object has a method named "getName", and if the result of calling object.getName() is "Larry Fine", then the JSONObject will contain "name": "Larry Fine".
      Parameters:
      bean - An object that has getter methods that should be used to make a JSONObject.

  • Method Details

    • parse

      public static JSONObject parse(String source)
      Construct a JSONObject from a source JSON text string. This is the most commonly used JSONObject constructor.
      Parameters:
      source - A string beginning with { (left brace) and ending with } (right brace).
      Throws:
      RuntimeException - If there is a syntax error in the source string or a duplicated key.

    • doubleToString

      protected static String doubleToString(double d)
      Produce a string from a double. The string "null" will be returned if the number is not finite.
      Parameters:
      d - A double.
      Returns:
      A String.

    • get

      public Object get(String key)
      Get the value object associated with a key.
      Parameters:
      key - A key string.
      Returns:
      The object associated with the key.
      Throws:
      RuntimeException - if the key is not found.

    • getString

      public String getString(String key)
      Gets the String value associated with the specified key.
      Parameters:
      key - a key string
      Returns:
      A string which is the value.
      Throws:
      RuntimeException - if there is no string value for the key.
      See Also:

    • getString

      public String getString(String key, String defaultValue)
      Get an optional string associated with a key. It returns the defaultValue if there is no such key.
      Parameters:
      key - A key string.
      defaultValue - The default.
      Returns:
      A string which is the value.

    • getInt

      public int getInt(String key)
      Gets the int value associated with the specified key.
      Parameters:
      key - A key string.
      Returns:
      The integer value.
      Throws:
      RuntimeException - if the key is not found or if the value cannot be converted to an integer.
      See Also:

    • getInt

      public int getInt(String key, int defaultValue)
      Get an optional int value associated with a key, or the default if there is no such key or if the value is not a number. If the value is a string, an attempt will be made to evaluate it as a number.
      Parameters:
      key - A key string.
      defaultValue - The default.
      Returns:
      An object which is the value.

    • getLong

      public long getLong(String key)
      Get the long value associated with a key.
      Parameters:
      key - A key string.
      Returns:
      The long value.
      Throws:
      RuntimeException - if the key is not found or if the value cannot be converted to a long.

    • getLong

      public long getLong(String key, long defaultValue)
      Get an optional long value associated with a key, or the default if there is no such key or if the value is not a number. If the value is a string, an attempt will be made to evaluate it as a number.
      Parameters:
      key - A key string.
      defaultValue - The default.
      Returns:
      An object which is the value.

    • getFloat

      public float getFloat(String key)
      Gets the float value associated with the specified key
      Parameters:
      key - a key string
      See Also:

    • getFloat

      public float getFloat(String key, float defaultValue)

    • getDouble

      public double getDouble(String key)
      Get the double value associated with a key.
      Parameters:
      key - A key string.
      Returns:
      The numeric value.
      Throws:
      RuntimeException - if the key is not found or if the value is not a Number object and cannot be converted to a number.

    • getDouble

      public double getDouble(String key, double defaultValue)
      Get an optional double associated with a key, or the defaultValue if there is no such key or if its value is not a number. If the value is a string, an attempt will be made to evaluate it as a number.
      Parameters:
      key - A key string.
      defaultValue - The default.
      Returns:
      An object which is the value.

    • getBoolean

      public boolean getBoolean(String key)
      Gets the boolean value associated with the specified key.
      Parameters:
      key - a key string
      Returns:
      The truth.
      Throws:
      RuntimeException - if the value is not a Boolean or the String "true" or "false".
      See Also:

    • getBoolean

      public boolean getBoolean(String key, boolean defaultValue)
      Get an optional boolean associated with a key. It returns the defaultValue if there is no such key, or if it is not a Boolean or the String "true" or "false" (case insensitive).
      Parameters:
      key - A key string.
      defaultValue - The default.
      Returns:
      The truth.

    • getJSONArray

      public JSONArray getJSONArray(String key)
      Retrieves the JSONArray with the associated key.
      Parameters:
      key - a key string
      Returns:
      A JSONArray which is the value, or null if not present
      Throws:
      RuntimeException - if the value is not a JSONArray.
      See Also:

    • getIntList

      public IntList getIntList(String key)

    • getLongList

      public LongList getLongList(String key)

    • getFloatList

      public FloatList getFloatList(String key)

    • getDoubleList

      public DoubleList getDoubleList(String key)

    • getStringList

      public StringList getStringList(String key)

    • getJSONObject

      public JSONObject getJSONObject(String key)
      Given a key value, retrieves the associated JSONObject.
      Parameters:
      key - a key string
      Returns:
      A JSONObject which is the value or null if not available.
      Throws:
      RuntimeException - if the value is not a JSONObject.
      See Also:

    • hasKey

      public boolean hasKey(String key)
      Determine if the JSONObject contains a specific key.
      Parameters:
      key - A key string.
      Returns:
      true if the key exists in the JSONObject.

    • isNull

      public boolean isNull(String key)
      Determines if the value associated with the key is null, that is has no defined value (false) or if it has a value (true).
      Parameters:
      key - A key string.
      Returns:
      true if there is no value associated with the key or if the value is the JSONObject.NULL object.

    • keyIterator

      public Iterator keyIterator()
      Get an enumeration of the keys of the JSONObject.
      Returns:
      An iterator of the keys.

    • keys

      public Set keys()
      Get a set of keys of the JSONObject.
      Returns:
      A keySet.

    • size

      public int size()
      Get the number of keys stored in the JSONObject.
      Returns:
      The number of keys in the JSONObject.

    • setString

      public JSONObject setString(String key, String value)
      Inserts a new key/String pair into the JSONObject or, if a value with the specified key already exists, assigns a new value.
      Parameters:
      key - a key string
      value - the value to assign
      See Also:

    • setInt

      public JSONObject setInt(String key, int value)
      Inserts a new key/int pair into the JSONObject or, if a value with the specified key already exists, assigns a new value.
      Parameters:
      key - a key string
      value - the value to assign
      Returns:
      this.
      Throws:
      RuntimeException - If the key is null.
      See Also:

    • setLong

      public JSONObject setLong(String key, long value)
      Put a key/long pair in the JSONObject.
      Parameters:
      key - A key string.
      value - A long which is the value.
      Returns:
      this.
      Throws:
      RuntimeException - If the key is null.

    • setFloat

      public JSONObject setFloat(String key, float value)
      Inserts a new key/float pair into the JSONObject or, if a value with the specified key already exists, assigns a new value.
      Parameters:
      key - a key string
      value - the value to assign
      Throws:
      RuntimeException - If the key is null or if the number is NaN or infinite.
      See Also:

    • setDouble

      public JSONObject setDouble(String key, double value)
      Put a key/double pair in the JSONObject.
      Parameters:
      key - A key string.
      value - A double which is the value.
      Returns:
      this.
      Throws:
      RuntimeException - If the key is null or if the number is NaN or infinite.

    • setBoolean

      public JSONObject setBoolean(String key, boolean value)
      Inserts a new key/boolean pair into the JSONObject or, if a value with the specified key already exists, assigns a new value.
      Parameters:
      key - a key string
      value - the value to assign
      Returns:
      this.
      Throws:
      RuntimeException - If the key is null.
      See Also:

    • setJSONObject

      public JSONObject setJSONObject(String key, JSONObject value)
      Sets the value of the JSONObject with the associated key.
      Parameters:
      key - a key string
      value - value to assign
      See Also:

    • setJSONArray

      public JSONObject setJSONArray(String key, JSONArray value)
      Sets the value of the JSONArray with the associated key.
      Parameters:
      key - a key string
      value - value to assign
      See Also:

    • put

      public JSONObject put(String key, Object value)
      Put a key/value pair in the JSONObject. If the value is null, then the key will be removed from the JSONObject if it is present.
      Parameters:
      key - A key string.
      value - An object which is the value. It should be of one of these types: Boolean, Double, Integer, JSONArray, JSONObject, Long, String, or the JSONObject.NULL object.
      Returns:
      this.
      Throws:
      RuntimeException - If the value is non-finite number or if the key is null.

    • quote

      public static String quote(String string)
      Produce a string in double quotes with backslash sequences in all the right places. A backslash will be inserted within </, producing <\/, allowing JSON text to be delivered in HTML. In JSON text, a string cannot contain a control character or an unescaped quote or backslash.
      Parameters:
      string - A String
      Returns:
      A String correctly formatted for insertion in a JSON text.

    • quote

      public static Writer quote(String string, Writer w) throws IOException
      Throws:
      IOException

    • remove

      public Object remove(String key)
      Remove a name and its value, if present.
      Parameters:
      key - The name to be removed.
      Returns:
      The value that was associated with the name, or null if there was no value.

    • stringToValue

      protected static Object stringToValue(String string)
      Try to convert a string into a number, boolean, or null. If the string can't be converted, return the string.
      Parameters:
      string - A String.
      Returns:
      A simple JSON value.

    • testValidity

      protected static void testValidity(Object o)
      Throw an exception if the object is a NaN or infinite number.
      Parameters:
      o - The object to test. If not Float or Double, accepted without exceptions.
      Throws:
      RuntimeException - If o is infinite or NaN.

    • save

      public boolean save(File file, String options)

    • write

      public boolean write(PrintWriter output)

    • write

      public boolean write(PrintWriter output, String options)

    • toString

      public String toString()
      Return the JSON data formatted with two spaces for indents. Chosen to do this since it's the most common case (e.g. with println()). Same as format(2). Use the format() function for more options.
      Overrides:
      toString in class Object

    • format

      public String format(int indentFactor)
      Make a prettyprinted JSON text of this JSONObject.

      Warning: This method assumes that the data structure is acyclical.

      Parameters:
      indentFactor - The number of spaces to add to each level of indentation.
      Returns:
      a printable, displayable, portable, transmittable representation of the object, beginning with { (left brace) and ending with } (right brace).
      Throws:
      RuntimeException - If the object contains an invalid number.

    • valueToString

      protected static String valueToString(Object value)
      Make a JSON text of an Object value. If the object has an value.toJSONString() method, then that method will be used to produce the JSON text. The method is required to produce a strictly conforming text. If the object does not contain a toJSONString method (which is the most common case), then a text will be produced by other means. If the value is an array or Collection, then a JSONArray will be made from it and its toJSONString method will be called. If the value is a MAP, then a JSONObject will be made from it and its toJSONString method will be called. Otherwise, the value's toString method will be called, and the result will be quoted.

      Warning: This method assumes that the data structure is acyclical.

      Parameters:
      value - The value to be serialized.
      Returns:
      a printable, displayable, transmittable representation of the object, beginning with { (left brace) and ending with } (right brace).
      Throws:
      RuntimeException - If the value is or contains an invalid number.

    • wrap

      protected static Object wrap(Object object)
      Wrap an object, if necessary. If the object is null, return the NULL object. If it is an array or collection, wrap it in a JSONArray. If it is a map, wrap it in a JSONObject. If it is a standard property (Double, String, et al) then it is already wrapped. Otherwise, if it comes from one of the java packages, turn it into a string. And if it doesn't, try to wrap it in a JSONObject. If the wrapping fails, then null is returned.
      Parameters:
      object - The object to wrap
      Returns:
      The wrapped value

    • writeInternal

      protected Writer writeInternal(Writer writer, int indentFactor, int indent)
      Write the contents of the JSONObject as JSON text to a writer.

      Warning: This method assumes that the data structure is acyclical.

      Returns:
      The writer.
      Throws:
      RuntimeException