Class JSONObject

java.lang.Object
org.apache.tapestry5.json.JSONCollection
org.apache.tapestry5.json.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:
  • Nested Class Summary

    Nested classes/interfaces inherited from interface java.util.Map

    Map.Entry<K extends Object,V extends Object>
  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final Object
    A sentinel value used to explicitly define a name with no value.
  • Constructor Summary

    Constructors
    Constructor
    Description
    Creates a JSONObject with no name/value mappings.
    JSONObject(Object... keysAndValues)
    Constructs a new JSONObject using a series of String keys and object values.
    Creates a new JSONObject with name/value mappings from the JSON string.
    JSONObject(JSONObject copyFrom, String... names)
    Creates a new JSONObject by copying mappings for the listed names from the given object.
  • Method Summary

    Modifier and Type
    Method
    Description
    accumulate(String name, Object value)
    Appends value to the array already mapped to name.
    append(String name, Object value)
    Appends values to the array mapped to name.
    void
    Removes all of the mappings from this JSONObject.
    boolean
    Returns true if this JSONObject contains a mapping for the specified key.
    boolean
    Returns true if this JSONObject maps one or more keys to the specified value.
    Returns a new JSONObject that is a shallow copy of this JSONObject.
    Returns a Set view of the mappings contained in this JSONObject.
    boolean
     
    get(Object name)
    Returns the value mapped by name, or throws if no such mapping exists.
    boolean
    Returns the value mapped by name if it exists and is a boolean or can be coerced to a boolean, or throws otherwise.
    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.
    double
    Returns the value mapped by name if it exists and is a double or can be coerced to a double, or throws otherwise.
    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.
    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.
    Returns the value mapped by name if it exists and is a JSONArray, or throws otherwise.
    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.
    Returns the value mapped by name if it exists and is a JSONObject, or throws otherwise.
    Returns the value to which the specified key is mapped and a JSONObject, or defaultValue if this map contains no mapping for the key.
    long
    Returns the value mapped by name if it exists and is a long or can be coerced to a long, or throws otherwise.
    long
    getLongOrDefault(String name, long 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.
    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.
    Returns the value mapped by name if it exists, coercing it if necessary, or throws if no such mapping exists.
    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.
    boolean
    has(String name)
    Deprecated.
    int
     
    in(String key)
    Navigates into a nested JSONObject, creating the JSONObject if necessary.
    boolean
    Returns true if this JSONObject contains no key-value mappings.
    boolean
    isNull(String name)
    Returns true if this object has no mapping for name or if it has a mapping whose value is NULL.
    Returns the set of String names in this object.
    Returns a Set view of the keys contained in this JSONObject.
    int
    Deprecated.
    Use size() instead.
    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.
    Returns an array containing the string names in this object.
    static String
    Encodes the number as a JSON string.
    opt(Object name)
    Returns the value mapped by name, or null if no such mapping exists.
    put(String name, Object value)
    Maps name to value, clobbering any existing name/value mapping with the same name.
    void
    putAll(Map<? extends String,? extends Object> newProperties)
    Invokes put(String, Object) for each value from the map.
    static String
    quote(String data)
    Encodes data as a JSON string.
    remove(Object name)
    Removes the named mapping if it exists; does nothing otherwise.
    int
    Returns the number of key-value mappings in this JSONObject.
    Returns a Map of the keys and values of the JSONObject.
    Returns a Collection view of the values contained in this JSONObject.

    Methods inherited from class org.apache.tapestry5.json.JSONCollection

    prettyPrint, print, print, toCompactString, toString, toString

    Methods inherited from class java.lang.Object

    clone, finalize, getClass, notify, notifyAll, wait, wait, wait

    Methods inherited from interface java.util.Map

    compute, computeIfAbsent, computeIfPresent, forEach, putIfAbsent, remove, replace, replace, replaceAll
  • Field Details

  • Constructor Details

    • 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 Details

    • 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.
      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, long 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
    • getJSONArray

      public JSONArray getJSONArray(String name)
      Returns the value mapped by name if it exists and is a JSONArray, or throws otherwise.
      Parameters:
      name - The field we want to get.
      Returns:
      The value of the field (if it is a JSONArray.
      Throws:
      JSONValueNotFoundException - if the mapping doesn't exist
      JSONTypeMismatchException - if the mapping is not a JSONArray.
    • 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
    • getJSONObject

      Returns the value mapped by name if it exists and is a JSONObject, or throws otherwise.
      Parameters:
      name - The name of the field that we want.
      Returns:
      a specified field value (if it is a JSONObject)
      Throws:
      JSONValueNotFoundException - if the mapping doesn't exist
      JSONTypeMismatchException - if the mapping is not a JSONObject.
    • 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.
    • equals

      public boolean equals(Object obj)
      Specified by:
      equals in interface Map<String,Object>
      Overrides:
      equals in class Object
    • hashCode

      public int hashCode()
      Specified by:
      hashCode in interface Map<String,Object>
      Overrides:
      hashCode in class Object
    • 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.
    • putAll

      public void putAll(Map<? extends String,? extends Object> newProperties)
      Invokes put(String, Object) for each value from the map.
      Specified by:
      putAll in interface Map<String,Object>
      Parameters:
      newProperties - to add to this JSONObject
      Since:
      5.7
    • 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

      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

      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