Package org.apache.tapestry5.json

Class JSONObject

  • All Implemented Interfaces:
    Serializable, Map<String,​Object>
    public final class JSONObject
extends JSONCollection
implements Map<String,​Object>
    A modifiable set of name/value mappings. Names are unique, non-null strings. Values may be any mix of JSONObjects, JSONArrays, Strings, Booleans, Integers, Longs, Doubles or NULL. Values may not be null, NaNs, infinities, or of any type not listed here.

    This class can coerce values to another type when requested.

    • When the requested type is a boolean, strings will be coerced using a case-insensitive comparison to "true" and "false".
    • When the requested type is a double, other Number types will be coerced using doubleValue. Strings that can be coerced using Double.valueOf(String) will be.
    • When the requested type is an int, other Number types will be coerced using intValue. Strings that can be coerced using Double.valueOf(String) will be, and then cast to int.
    • When the requested type is a long, other Number types will be coerced using longValue. Strings that can be coerced using Double.valueOf(String) will be, and then cast to long. This two-step conversion is lossy for very large values. For example, the string "9223372036854775806" yields the long 9223372036854775807.
    • When the requested type is a String, other non-null values will be coerced using String.valueOf(Object). Although null cannot be coerced, the sentinel value NULL is coerced to the string "null".

    This class can look up both mandatory and optional values:

    • Use getType() to retrieve a mandatory value. This fails with a RuntimeException if the requested name has no value or if the value cannot be coerced to the requested type.
    • Use opt() to retrieve an optional value.

    Warning: this class represents null in two incompatible ways: the standard Java null reference, and the sentinel value NULL. In particular, calling put(name, null) removes the named entry from the object but put(name, JSONObject.NULL) stores an entry whose value is JSONObject.NULL.

    Instances of this class are not thread safe.

    See Also:
    Serialized Form

    • Constructor Detail

      • JSONObject

        public JSONObject()
        Creates a JSONObject with no name/value mappings.

      • JSONObject

        public JSONObject​(String json)
        Creates a new JSONObject with name/value mappings from the JSON string.
        Parameters:
        json - a JSON-encoded string containing an object.
        Throws:
        RuntimeException - if the parse fails or doesn't yield a JSONObject.

      • JSONObject

        public JSONObject​(JSONObject copyFrom,
                  String... names)
        Creates a new JSONObject by copying mappings for the listed names from the given object. Names that aren't present in copyFrom will be skipped.
        Parameters:
        copyFrom - The source object.
        names - The names of the fields to copy.
        Throws:
        RuntimeException - On internal errors. Shouldn't happen.

      • JSONObject

        public JSONObject​(Object... keysAndValues)
        Constructs a new JSONObject using a series of String keys and object values. Object values should be compatible with put(String, Object). Keys must be strings (toString() will be invoked on each key). Prior to release 5.4, keysAndValues was type String...; changing it to Object... makes it much easier to initialize a JSONObject in a single statement, which is more readable.
        Since:
        5.2.0

    • Method Detail

      • copy

        public JSONObject copy()
        Returns a new JSONObject that is a shallow copy of this JSONObject.
        Since:
        5.4

      • length

        @Deprecated
public int length()
        Deprecated.
        Use size() instead.
        Returns the number of name/value mappings in this object.
        Returns:
        the length of this.

      • put

        public JSONObject put​(String name,
                      Object value)
        Maps name to value, clobbering any existing name/value mapping with the same name. If the value is null, any existing mapping for name is removed.
        Specified by:
        put in interface Map<String,​Object>
        Parameters:
        name - The name of the new value.
        value - a JSONObject, JSONArray, String, Boolean, Integer, Long, Double, NULL, or null. May not be NaNs or infinities.
        Returns:
        this object.
        Throws:
        IllegalArgumentException - if the value is an invalid double (infinite or NaN).

      • accumulate

        public JSONObject accumulate​(String name,
                             Object value)
        Appends value to the array already mapped to name. If this object has no mapping for name, this inserts a new mapping. If the mapping exists but its value is not an array, the existing and new values are inserted in order into a new array which is itself mapped to name. In aggregate, this allows values to be added to a mapping one at a time. Note that append(String, Object) provides better semantics. In particular, the mapping for name will always be a JSONArray. Using accumulate will result in either a JSONArray or a mapping whose type is the type of value depending on the number of calls to it.
        Parameters:
        name - The name of the field to change.
        value - a JSONObject, JSONArray, String, Boolean, Integer, Long, Double, NULL or null. May not be NaNs or infinities.
        Returns:
        this object after mutation.
        Throws:
        RuntimeException - If the object being added is an invalid number.

      • append

        public JSONObject append​(String name,
                         Object value)
        Appends values to the array mapped to name. A new JSONArray mapping for name will be inserted if no mapping exists. If the existing mapping for name is not a JSONArray, a RuntimeException will be thrown.
        Parameters:
        name - The name of the array to which the value should be appended.
        value - The value to append.
        Returns:
        this object.
        Throws:
        JSONTypeMismatchException - if name is null or if the mapping for name is non-null and is not a JSONArray.

      • isNull

        public boolean isNull​(String name)
        Returns true if this object has no mapping for name or if it has a mapping whose value is NULL.
        Parameters:
        name - The name of the value to check on.
        Returns:
        true if the field doesn't exist or is null.

      • has

        @Deprecated
public boolean has​(String name)
        Deprecated.
        use containsKey(Object) instead
        Returns true if this object has a mapping for name. The mapping may be NULL.
        Parameters:
        name - The name of the value to check on.
        Returns:
        true if this object has a field named name

      • opt

        public Object opt​(Object name)
        Returns the value mapped by name, or null if no such mapping exists.
        Parameters:
        name - The name of the value to get.
        Returns:
        The value.

      • getBoolean

        public boolean getBoolean​(String name)
        Returns the value mapped by name if it exists and is a boolean or can be coerced to a boolean, or throws otherwise.
        Parameters:
        name - The name of the field we want.
        Returns:
        The selected value if it exists.
        Throws:
        JSONValueNotFoundException - if the mapping doesn't exist
        JSONTypeMismatchException - if the mapping cannot be coerced to a boolean.

      • getBooleanOrDefault

        public boolean getBooleanOrDefault​(String name,
                                   boolean defaultValue)
        Returns the value to which the specified key is mapped and a boolean, or defaultValue if this JSONObject contains no mapping for the key.
        Parameters:
        name - the key whose associated value is to be returned
        defaultValue - the default mapping of the key
        Returns:
        the value to which the specified key is mapped, or defaultValue if this JSONObject contains no mapping for the key
        Throws:
        JSONTypeMismatchException - if the mapping cannot be coerced to a boolean.
        Since:
        5.7

      • getDouble

        public double getDouble​(String name)
        Returns the value mapped by name if it exists and is a double or can be coerced to a double, or throws otherwise.
        Parameters:
        name - The name of the field we want.
        Returns:
        The selected value if it exists.
        Throws:
        JSONValueNotFoundException - if the mapping doesn't exist
        JSONTypeMismatchException - if the mapping cannot be coerced to a double.

      • getInt

        public int getInt​(String name)
        Returns the value mapped by name if it exists and is an int or can be coerced to an int, or throws otherwise.
        Parameters:
        name - The name of the field we want.
        Returns:
        The selected value if it exists.
        Throws:
        JSONValueNotFoundException - if the mapping doesn't exist
        JSONTypeMismatchException - if the mapping cannot be coerced to an int.

      • getIntOrDefault

        public int getIntOrDefault​(String name,
                           int defaultValue)
        Returns the value to which the specified key is mapped and an int, or defaultValue if this JSONObject contains no mapping for the key.
        Parameters:
        name - the key whose associated value is to be returned
        defaultValue - the default mapping of the key
        Returns:
        the value to which the specified key is mapped, or defaultValue if this JSONObject contains no mapping for the key
        Throws:
        JSONTypeMismatchException - if the mapping cannot be coerced to an int.
        Since:
        5.7

      • getLong

        public long getLong​(String name)
        Returns the value mapped by name if it exists and is a long or can be coerced to a long, or throws otherwise. Note that JSON represents numbers as doubles, so this is lossy; use strings to transfer numbers via JSON without loss.
        Parameters:
        name - The name of the field that we want.
        Returns:
        The value of the field.
        Throws:
        JSONValueNotFoundException - if the mapping doesn't exist
        JSONTypeMismatchException - if the mapping cannot be coerced to a long.

      • getLongOrDefault

        public long getLongOrDefault​(String name,
                             int defaultValue)
        Returns the value to which the specified key is mapped and a long, or defaultValue if this JSONObject contains no mapping for the key.
        Parameters:
        name - the key whose associated value is to be returned
        defaultValue - the default mapping of the key
        Returns:
        the value to which the specified key is mapped, or defaultValue if this JSONObject contains no mapping for the key
        Throws:
        JSONTypeMismatchException - if the mapping cannot be coerced to a long.
        Since:
        5.7

      • getString

        public String getString​(String name)
        Returns the value mapped by name if it exists, coercing it if necessary, or throws if no such mapping exists.
        Parameters:
        name - The name of the field we want.
        Returns:
        The value of the field.
        Throws:
        JSONValueNotFoundException - if the mapping doesn't exist
        JSONTypeMismatchException - if the mapping cannot be coerced to String

      • getStringOrDefault

        public String getStringOrDefault​(String name,
                                 String defaultValue)
        Returns the value to which the specified key is mapped and a string, or defaultValue if this JSONObject contains no mapping for the key.
        Parameters:
        name - the key whose associated value is to be returned
        defaultValue - the default mapping of the key
        Returns:
        the value to which the specified key is mapped, or defaultValue if this JSONObject contains no mapping for the key
        Throws:
        JSONTypeMismatchException - if the mapping cannot be coerced to a string.
        Since:
        5.7

      • getJSONArrayOrDefault

        public JSONArray getJSONArrayOrDefault​(String name,
                                       JSONArray defaultValue)
        Returns the value to which the specified key is mapped and a JSONArray, or defaultValue if this JSONObject contains no mapping for the key.
        Parameters:
        name - the key whose associated value is to be returned
        defaultValue - the default mapping of the key
        Returns:
        the value to which the specified key is mapped, or defaultValue if this JSONObject contains no mapping for the key
        Throws:
        JSONTypeMismatchException - if the mapping cannot be coerced to a JSONArray.
        Since:
        5.7

      • getJSONObjectOrDefault

        public JSONObject getJSONObjectOrDefault​(String name,
                                         JSONObject defaultValue)
        Returns the value to which the specified key is mapped and a JSONObject, or defaultValue if this map contains no mapping for the key.
        Parameters:
        name - the key whose associated value is to be returned
        defaultValue - the default mapping of the key
        Returns:
        the value to which the specified key is mapped, or defaultValue if this map contains no mapping for the key
        Throws:
        JSONTypeMismatchException - if the mapping cannot be coerced to a JSONObject.
        Since:
        5.7

      • keys

        public Set<String> keys()
        Returns the set of String names in this object. The returned set is a view of the keys in this object. Set.remove(Object) will remove the corresponding mapping from this object and set iterator behaviour is undefined if this object is modified after it is returned. See keys().
        Returns:
        The names in this object.

      • names

        public JSONArray names()
        Returns an array containing the string names in this object. This method returns null if this object contains no mappings.
        Returns:
        the names.

      • numberToString

        public static String numberToString​(Number number)
        Encodes the number as a JSON string.
        Parameters:
        number - a finite value. May not be NaNs or infinities.
        Returns:
        The encoded number in string form.
        Throws:
        RuntimeException - On internal errors. Shouldn't happen.

      • quote

        public static String quote​(String data)
        Encodes data as a JSON string. This applies quotes and any necessary character escaping.
        Parameters:
        data - the string to encode. Null will be interpreted as an empty string.
        Returns:
        the quoted string.

      • toMap

        public Map<String,​Object> toMap()
        Returns a Map of the keys and values of the JSONObject. The returned map is unmodifiable. Note that changes to the JSONObject will be reflected in the map. In addition, null values in the JSONObject are represented as NULL in the map.
        Returns:
        unmodifiable map of properties and values
        Since:
        5.4

      • in

        public JSONObject in​(String key)
        Navigates into a nested JSONObject, creating the JSONObject if necessary. They key must not exist, or must be a JSONObject.
        Parameters:
        key -
        Returns:
        the nested JSONObject
        Throws:
        IllegalStateException - if the current value for the key is not null and not JSONObject

      • size

        public int size()
        Returns the number of key-value mappings in this JSONObject. If it contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.
        Specified by:
        size in interface Map<String,​Object>
        Returns:
        the number of key-value mappings in this JSONObject
        Since:
        5.7

      • isEmpty

        public boolean isEmpty()
        Returns true if this JSONObject contains no key-value mappings.
        Specified by:
        isEmpty in interface Map<String,​Object>
        Returns:
        true if this JSONObject contains no key-value mappings
        Since:
        5.7

      • containsKey

        public boolean containsKey​(Object key)
        Returns true if this JSONObject contains a mapping for the specified key.
        Specified by:
        containsKey in interface Map<String,​Object>
        Parameters:
        key - key whose presence in this map is to be tested
        Returns:
        true if this map contains a mapping for the specified key
        Since:
        5.7

      • containsValue

        public boolean containsValue​(Object value)
        Returns true if this JSONObject maps one or more keys to the specified value.
        Specified by:
        containsValue in interface Map<String,​Object>
        Parameters:
        value - value whose presence in this map is to be tested
        Returns:
        true if this JSONObject maps one or more keys to the specified value
        Since:
        5.7

      • get

        public Object get​(Object name)
        Returns the value mapped by name, or throws if no such mapping exists.
        Specified by:
        get in interface Map<String,​Object>
        Parameters:
        name - The name of the value to get.
        Returns:
        The value.
        Throws:
        JSONValueNotFoundException - if no such mapping exists.

      • getOrDefault

        public Object getOrDefault​(Object key,
                           Object defaultValue)
        Returns the value to which the specified key is mapped, or defaultValue if this JSONObject contains no mapping for the key.
        Specified by:
        getOrDefault in interface Map<String,​Object>
        Parameters:
        key - the key whose associated value is to be returned
        defaultValue - the default mapping of the key
        Returns:
        the value to which the specified key is mapped, or defaultValue if this JSONObject contains no mapping for the key
        Since:
        5.7

      • remove

        public Object remove​(Object name)
        Removes the named mapping if it exists; does nothing otherwise.
        Specified by:
        remove in interface Map<String,​Object>
        Parameters:
        name - The name of the mapping to remove.
        Returns:
        the value previously mapped by name, or null if there was no such mapping.

      • clear

        public void clear()
        Removes all of the mappings from this JSONObject.
        Specified by:
        clear in interface Map<String,​Object>
        Since:
        5.7

      • keySet

        public Set<String> keySet()
        Returns a Set view of the keys contained in this JSONObject. The set is backed by the JSONObject, so changes to the map are reflected in the set, and vice-versa.
        Specified by:
        keySet in interface Map<String,​Object>
        Returns:
        a set view of the keys contained in this JSONObject
        Since:
        5.7

      • values

        public Collection<Object> values()
        Returns a Collection view of the values contained in this JSONObject. The collection is backed by the JSONObject, so changes to the map are reflected in the collection, and vice-versa.
        Specified by:
        values in interface Map<String,​Object>
        Returns:
        a collection view of the values contained in this JSONObject
        Since:
        5.7

      • entrySet

        public Set<Map.Entry<String,​Object>> entrySet()
        Returns a Set view of the mappings contained in this JSONObject. The set is backed by the JSONObject, so changes to the map are reflected in the set, and vice-versa.
        Specified by:
        entrySet in interface Map<String,​Object>
        Returns:
        a set view of the mappings contained in this JSONObject
        Since:
        5.7

      • merge

        public Object merge​(String key,
                    Object value,
                    BiFunction<? super Object,​? super Object,​? extends Object> remappingFunction)
        If the specified key is not already associated with a value or is associated with null, associates it with the given non-null value. Otherwise, replaces the associated value with the results of the given remapping function, or removes if the result is null.
        Specified by:
        merge in interface Map<String,​Object>
        Parameters:
        key - key with which the resulting value is to be associated
        value - the non-null value to be merged with the existing value associated with the key or, if no existing value or a null value is associated with the key, to be associated with the key
        remappingFunction - the function to recompute a value if present
        Returns:
        the new value associated with the specified key, or null if no value is associated with the key
        Throws:
        NullPointerException - if the specified key is null or the value or remappingFunction is null
        Since:
        5.7