Package org.json.me

Class JSONObject

  • public class JSONObject
extends Object
    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 coersion for you.

    The put methods adds values to 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 sysntax 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).
    • Numbers may have the 0- (octal) or 0x- (hex) prefix.
    • Comments written in the slashshlash, slashstar, and hash conventions will be ignored.

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      static class  JSONObject.Util  

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static Object NULL
      It is sometimes more convenient and less ambiguous to have a NULL object than to use Java's null value.

    • Field Detail

      • 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 Detail

      • JSONObject

        public JSONObject()
        Construct an empty JSONObject.

      • JSONObject

        public JSONObject​(JSONObject jo,
                  String[] sa)
           throws JSONException
        Construct a JSONObject from a subset of another JSONObject. An array of strings is used to identify the keys that should be copied. Missing keys are ignored.
        Parameters:
        jo - A JSONObject.
        sa - An array of strings.
        Throws:
        JSONException - If a value is a non-finite number.

      • JSONObject

        public JSONObject​(JSONTokener x)
           throws JSONException
        Construct a JSONObject from a JSONTokener.
        Parameters:
        x - A JSONTokener object containing the source string.
        Throws:
        JSONException - If there is a syntax error in the source string or a duplicated key.

      • JSONObject

        public JSONObject​(@Nullable
                  Map<?,​?> 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​(String string)
           throws JSONException
        Construct a JSONObject from a string. This is the most commonly used JSONObject constructor.
        Parameters:
        string - A string beginning with { (left brace) and ending with }  (right brace).
        Throws:
        JSONException - If there is a syntax error in the source string.

    • Method Detail

      • stringToValue

        public 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.

      • accumulate

        public JSONObject accumulate​(String key,
                             Object value)
                      throws JSONException
        Accumulate values under a key. It is similar to the put method except that if there is already an object stored under the key then a JSONArray is stored under the key to hold all of the accumulated values. If there is already a JSONArray, then the new value is appended to it. In contrast, the put method replaces the previous value.
        Parameters:
        key - A key string.
        value - An object to be accumulated under the key.
        Returns:
        this.
        Throws:
        JSONException - If the value is an invalid number or if the key is null.

      • append

        public JSONObject append​(String key,
                         Object value)
                  throws JSONException
        Append values to the array under a key. If the key does not exist in the JSONObject, then the key is put in the JSONObject with its value being a JSONArray containing the value parameter. If the key was already associated with a JSONArray, then the value parameter is appended to it.
        Parameters:
        key - A key string.
        value - An object to be accumulated under the key.
        Returns:
        this.
        Throws:
        JSONException - If the key is null or if the current value associated with the key is not a JSONArray.

      • doubleToString

        public 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)
           throws JSONException
        Get the value object associated with a key.
        Parameters:
        key - A key string.
        Returns:
        The object associated with the key.
        Throws:
        JSONException - if the key is not found.

      • getBoolean

        public boolean getBoolean​(String key)
                   throws JSONException
        Get the boolean value associated with a key.
        Parameters:
        key - A key string.
        Returns:
        The truth.
        Throws:
        JSONException - if the value is not a Boolean or the String "true" or "false".

      • getDouble

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

      • getInt

        public int getInt​(String key)
           throws JSONException
        Get the int value associated with a key. If the number value is too large for an int, it will be clipped.
        Parameters:
        key - A key string.
        Returns:
        The integer value.
        Throws:
        JSONException - if the key is not found or if the value cannot be converted to an integer.

      • getJSONArray

        public JSONArray getJSONArray​(String key)
                       throws JSONException
        Get the JSONArray value associated with a key.
        Parameters:
        key - A key string.
        Returns:
        A JSONArray which is the value.
        Throws:
        JSONException - if the key is not found or if the value is not a JSONArray.

      • getJSONObject

        public JSONObject getJSONObject​(String key)
                         throws JSONException
        Get the JSONObject value associated with a key.
        Parameters:
        key - A key string.
        Returns:
        A JSONObject which is the value.
        Throws:
        JSONException - if the key is not found or if the value is not a JSONObject.

      • getLong

        public long getLong​(String key)
             throws JSONException
        Get the long value associated with a key. If the number value is too long for a long, it will be clipped.
        Parameters:
        key - A key string.
        Returns:
        The long value.
        Throws:
        JSONException - if the key is not found or if the value cannot be converted to a long.

      • getString

        public String getString​(String key)
                 throws JSONException
        Get the string associated with a key.
        Parameters:
        key - A key string.
        Returns:
        A string which is the value.
        Throws:
        JSONException - if the key is not found.

      • has

        public boolean has​(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)
        Determine if the value associated with the key is null or if there is no value.
        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.

      • keys

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

      • keySet

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

      • length

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

      • names

        @Nullable
public JSONArray names()
        Produce a JSONArray containing the names of the elements of this JSONObject.
        Returns:
        A JSONArray containing the key strings, or null if the JSONObject is empty.

      • trimNumber

        public static String trimNumber​(String s)
        Shave off trailing zeros and decimal point, if possible.

      • numberToString

        public static String numberToString​(Object n)
                             throws JSONException
        Produce a string from a Number.
        Parameters:
        n - A Number
        Returns:
        A String.
        Throws:
        JSONException - If n is a non-finite number.

      • opt

        @Nullable
public Object opt​(@Nullable
                  String key)
        Get an optional value associated with a key.
        Parameters:
        key - A key string.
        Returns:
        An object which is the value, or null if there is no value.

      • optBoolean

        public boolean optBoolean​(String key)
        Get an optional boolean associated with a key. It returns false if there is no such key, or if the value is not Boolean.TRUE or the String "true".
        Parameters:
        key - A key string.
        Returns:
        The truth.

      • optBoolean

        public boolean optBoolean​(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.

      • optDouble

        public double optDouble​(String key)
        Get an optional double associated with a key, or NaN 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 string which is the key.
        Returns:
        An object which is the value.

      • optDouble

        public double optDouble​(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.

      • optInt

        public int optInt​(String key)
        Get an optional int value associated with a key, or zero 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.
        Returns:
        An object which is the value.

      • optInt

        public int optInt​(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.

      • optJSONArray

        @Nullable
public JSONArray optJSONArray​(String key)
        Get an optional JSONArray associated with a key. It returns null if there is no such key, or if its value is not a JSONArray.
        Parameters:
        key - A key string.
        Returns:
        A JSONArray which is the value.

      • optJSONObject

        @Nullable
public JSONObject optJSONObject​(String key)
        Get an optional JSONObject associated with a key. It returns null if there is no such key, or if its value is not a JSONObject.
        Parameters:
        key - A key string.
        Returns:
        A JSONObject which is the value.

      • optLong

        public long optLong​(String key)
        Get an optional long value associated with a key, or zero 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.
        Returns:
        An object which is the value.

      • optLong

        public long optLong​(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.

      • optString

        public String optString​(String key)
        Get an optional string associated with a key. It returns an empty string if there is no such key. If the value is not a string and is not null, then it is coverted to a string.
        Parameters:
        key - A key string.
        Returns:
        A string which is the value.

      • optString

        public String optString​(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.

      • put

        public JSONObject put​(String key,
                      boolean value)
               throws JSONException
        Put a key/boolean pair in the JSONObject.
        Parameters:
        key - A key string.
        value - A boolean which is the value.
        Returns:
        this.
        Throws:
        JSONException - If the key is null.

      • put

        public JSONObject put​(String key,
                      double value)
               throws JSONException
        Put a key/double pair in the JSONObject.
        Parameters:
        key - A key string.
        value - A double which is the value.
        Returns:
        this.
        Throws:
        JSONException - If the key is null or if the number is invalid.

      • put

        public JSONObject put​(String key,
                      int value)
               throws JSONException
        Put a key/int pair in the JSONObject.
        Parameters:
        key - A key string.
        value - An int which is the value.
        Returns:
        this.
        Throws:
        JSONException - If the key is null.

      • put

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

      • put

        public JSONObject put​(String key,
                      Map<?,​?> value)
               throws JSONException
        Put a key/value pair in the JSONObject, where the value will be a JSONObject which is produced from a Map.
        Parameters:
        key - A key string.
        value - A Map value.
        Returns:
        this.
        Throws:
        JSONException

      • put

        public JSONObject put​(String key,
                      @Nullable
                      Object value)
               throws JSONException
        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:
        JSONException - If the value is non-finite number or if the key is null.

      • putOnce

        public JSONObject putOnce​(@Nullable
                          String key,
                          @Nullable
                          Object value)
                   throws JSONException
        Put a key/value pair in the JSONObject, but only if the key and the value are both non-null, and only if there is not already a member with that name.
        Parameters:
        key - string
        value - object
        Returns:
        this.
        Throws:
        JSONException - if the key is a duplicate

      • putOpt

        public JSONObject putOpt​(@Nullable
                         String key,
                         @Nullable
                         Object value)
                  throws JSONException
        Put a key/value pair in the JSONObject, but only if the key and the value are both non-null.
        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:
        JSONException - If the value is a non-finite number.

      • quote

        public static String quote​(@Nullable
                           String string)
        Produce a string in double quotes with backslash sequences in all the right places. A backslash will be inserted within </, 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.

      • remove

        @Nullable
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.

      • toJSONArray

        @Nullable
public JSONArray toJSONArray​(@Nullable
                             JSONArray names)
                      throws JSONException
        Produce a JSONArray containing the values of the members of this JSONObject.
        Parameters:
        names - A JSONArray containing a list of key strings. This determines the sequence of the values in the result.
        Returns:
        A JSONArray of values.
        Throws:
        JSONException - If any of the values are non-finite numbers.

      • toString

        @Nullable
public String toString()
        Make a JSON text of this JSONObject. For compactness, no whitespace is added. If this would not result in a syntactically correct JSON text, then null will be returned instead.

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

        Overrides:
        toString in class Object
        Returns:
        a printable, displayable, portable, transmittable representation of the object, beginning with { (left brace) and ending with } (right brace).

      • toString

        public String toString​(int indentFactor)
                throws JSONException
        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:
        JSONException - If the object contains an invalid number.

      • wrap

        @Nullable
public static Object wrap​(@Nullable
                          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

      • write

        public Writer write​(Writer writer)
             throws JSONException
        Write the contents of the JSONObject as JSON text to a writer. For compactness, no whitespace is added.

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

        Returns:
        The writer.
        Throws:
        JSONException