Package io.microsphere.json

Class JSONObject

java.lang.Object

io.microsphere.json.JSONObject

public class JSONObject
extends java.lang.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 the special sentinel value NULL.

This class provides methods to store and retrieve values by their associated names, with support for type coercion when accessing values. It also includes functionality for converting the object to and from JSON formatted strings.

Example Usage

 // Creating a new JSONObject and adding key-value pairs
 JSONObject obj = new JSONObject();
 obj.put("name", "Alice");
 obj.put("age", 30);

 // Retrieving values
 String name = obj.getString("name"); // returns "Alice"
 int age = obj.getInt("age");         // returns 30

 // Using opt methods to provide default values
 boolean isMember = obj.optBoolean("isMember", false); // returns false if not present

 // Converting to JSON string
 String jsonStr = obj.toString(); // {"name":"Alice","age":30}

 // Parsing from JSON string
 String inputJson = "{\"city\":\"New York\",\"population\":8175133}";
 JSONObject parsedObj = new JSONObject(inputJson);
 String city = parsedObj.getString("city"); // "New York"
 

See Also:

JSONArray, JSONTokener

Field Summary

Fields

Modifier and Type	Field	Description
static java.lang.Object	NULL	A sentinel value used to explicitly define a name with no value.

Constructor Summary

Constructors

Constructor	Description
JSONObject()	Creates a JSONObject with no name/value mappings.
JSONObject(JSONObject copyFrom, java.lang.String[] names)	Creates a new JSONObject by copying mappings for the listed names from the given object.
JSONObject(JSONTokener readFrom)	Creates a new JSONObject with name/value mappings from the next object in the tokener.
JSONObject(java.lang.String json)	Creates a new JSONObject with name/value mappings from the JSON string.
JSONObject(java.util.Map copyFrom)	Creates a new JSONObject by copying all name/value mappings from the given map.

Method Summary

Modifier and Type	Method	Description
JSONObject	accumulate(java.lang.String name, java.lang.Object value)	Appends value to the array already mapped to name.
boolean	equals(java.lang.Object o)
java.lang.Object	get(java.lang.String name)	Returns the value mapped by name.
boolean	getBoolean(java.lang.String name)	Returns the value mapped by name if it exists and is a boolean or can be coerced to a boolean.
double	getDouble(java.lang.String name)	Returns the value mapped by name if it exists and is a double or can be coerced to a double.
int	getInt(java.lang.String name)	Returns the value mapped by name if it exists and is an int or can be coerced to an int.
JSONArray	getJSONArray(java.lang.String name)	Returns the value mapped by name if it exists and is a JSONArray.
JSONObject	getJSONObject(java.lang.String name)	Returns the value mapped by name if it exists and is a JSONObject.
long	getLong(java.lang.String name)	Returns the value mapped by name if it exists and is a long or can be coerced to a long.
java.lang.String	getString(java.lang.String name)	Returns the value mapped by name if it exists, coercing it if necessary.
boolean	has(java.lang.String name)	Returns true if this object has a mapping for name.
int	hashCode()
boolean	isNull(java.lang.String name)	Returns true if this object has no mapping for name or if it has a mapping whose value is NULL.
java.util.Iterator	keys()	Returns an iterator of the String names in this object.
int	length()	Returns the number of name/value mappings in this object.
JSONArray	names()	Returns an array containing the string names in this object.
static java.lang.String	numberToString(java.lang.Number number)	Encodes the number as a JSON string.
java.lang.Object	opt(java.lang.String name)	Returns the value mapped by name, or null if no such mapping exists.
boolean	optBoolean(java.lang.String name)	Returns the value mapped by name if it exists and is a boolean or can be coerced to a boolean.
boolean	optBoolean(java.lang.String name, boolean fallback)	Returns the value mapped by name if it exists and is a boolean or can be coerced to a boolean.
double	optDouble(java.lang.String name)	Returns the value mapped by name if it exists and is a double or can be coerced to a double.
double	optDouble(java.lang.String name, double fallback)	Returns the value mapped by name if it exists and is a double or can be coerced to a double.
int	optInt(java.lang.String name)	Returns the value mapped by name if it exists and is an int or can be coerced to an int.
int	optInt(java.lang.String name, int fallback)	Returns the value mapped by name if it exists and is an int or can be coerced to an int.
JSONArray	optJSONArray(java.lang.String name)	Returns the value mapped by name if it exists and is a JSONArray.
JSONObject	optJSONObject(java.lang.String name)	Returns the value mapped by name if it exists and is a JSONObject.
long	optLong(java.lang.String name)	Returns the value mapped by name if it exists and is a long or can be coerced to a long.
long	optLong(java.lang.String name, long fallback)	Returns the value mapped by name if it exists and is a long or can be coerced to a long.
java.lang.String	optString(java.lang.String name)	Returns the value mapped by name if it exists, coercing it if necessary.
java.lang.String	optString(java.lang.String name, java.lang.String fallback)	Returns the value mapped by name if it exists, coercing it if necessary.
JSONObject	put(java.lang.String name, boolean value)	Maps name to value, clobbering any existing name/value mapping with the same name.
JSONObject	put(java.lang.String name, double value)	Maps name to value, clobbering any existing name/value mapping with the same name.
JSONObject	put(java.lang.String name, int value)	Maps name to value, clobbering any existing name/value mapping with the same name.
JSONObject	put(java.lang.String name, long value)	Maps name to value, clobbering any existing name/value mapping with the same name.
JSONObject	put(java.lang.String name, java.lang.Object value)	Maps name to value, clobbering any existing name/value mapping with the same name.
JSONObject	putOpt(java.lang.String name, java.lang.Object value)	Equivalent to put(name, value) when both parameters are non-null; does nothing otherwise.
static java.lang.String	quote(java.lang.String data)	Encodes data as a JSON string.
java.lang.Object	remove(java.lang.String name)	Removes the named mapping if it exists; does nothing otherwise.
JSONArray	toJSONArray(JSONArray names)	Returns an array with the values corresponding to names.
java.lang.String	toString()	Encodes this object as a compact JSON string, such as:
java.lang.String	toString(int indentSpaces)	Encodes this object as a human-readable JSON string for debugging, such as:
static java.lang.Object	wrap(java.lang.Object o)	Wraps the given object if necessary.

Methods inherited from class java.lang.Object

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

Field Detail

NULL

public static final java.lang.Object NULL

A sentinel value used to explicitly define a name with no value. Unlike null, names with this value:

• show up in the names() array
• show up in the keys() iterator
• return true for has(String)
• do not throw on get(String)
• are included in the encoded JSON string.

This value violates the general contract of Object.equals(java.lang.Object) by returning true when compared to null. Its toString() method returns "null".

Constructor Detail

JSONObject

public JSONObject()

Creates a JSONObject with no name/value mappings.

JSONObject

public JSONObject(java.util.Map copyFrom)

Creates a new JSONObject by copying all name/value mappings from the given map.

Parameters:

copyFrom - a map whose keys are of type String and whose values are of supported types.

Throws:

java.lang.NullPointerException - if any of the map's keys are null.

JSONObject

public JSONObject(JSONTokener readFrom)
           throws JSONException

Creates a new JSONObject with name/value mappings from the next object in the tokener.

Parameters:

readFrom - a tokener whose nextValue() method will yield a JSONObject.

Throws:

JSONException - if the parse fails or doesn't yield a JSONObject.

JSONObject

public JSONObject(java.lang.String json)
           throws JSONException

Creates a new JSONObject with name/value mappings from the JSON string.

Parameters:

json - a JSON-encoded string containing an object.

Throws:

JSONException - if the parse fails or doesn't yield a JSONObject.

JSONObject

public JSONObject(JSONObject copyFrom,
                  java.lang.String[] names)
           throws JSONException

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

names - the property names

Throws:

JSONException - if an error occurs

Method Detail

length

public int length()

Returns the number of name/value mappings in this object.

Returns:

the number of name/value mappings in this object

put

public JSONObject put(java.lang.String name,
                      boolean value)
               throws JSONException

Maps name to value, clobbering any existing name/value mapping with the same name.

Parameters:

name - the name of the property

value - the value of the property

Returns:

this object.

Throws:

JSONException - if an error occurs

put

public JSONObject put(java.lang.String name,
                      double value)
               throws JSONException

Maps name to value, clobbering any existing name/value mapping with the same name.

Parameters:

name - the name of the property

value - a finite value. May not be NaNs or infinities.

Returns:

this object.

Throws:

JSONException - if an error occurs

put

public JSONObject put(java.lang.String name,
                      int value)
               throws JSONException

Maps name to value, clobbering any existing name/value mapping with the same name.

Parameters:

name - the name of the property

value - the value of the property

Returns:

this object.

Throws:

JSONException - if an error occurs

put

public JSONObject put(java.lang.String name,
                      long value)
               throws JSONException

Maps name to value, clobbering any existing name/value mapping with the same name.

Parameters:

name - the name of the property

value - the value of the property

Returns:

this object.

Throws:

JSONException - if an error occurs

put

public JSONObject put(java.lang.String name,
                      java.lang.Object value)
               throws JSONException

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.

Parameters:

name - the name of the property

value - a JSONObject, JSONArray, String, Boolean, Integer, Long, Double, NULL, or null. May not be NaNs or infinities.

Returns:

this object.

Throws:

JSONException - if an error occurs

putOpt

public JSONObject putOpt(java.lang.String name,
                         java.lang.Object value)
                  throws JSONException

Equivalent to put(name, value) when both parameters are non-null; does nothing otherwise.

Parameters:

name - the name of the property

value - the value of the property

Returns:

this object.

Throws:

JSONException - if an error occurs

accumulate

public JSONObject accumulate(java.lang.String name,
                             java.lang.Object value)
                      throws JSONException

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.

Parameters:

name - the name of the property

value - a JSONObject, JSONArray, String, Boolean, Integer, Long, Double, NULL or null. May not be NaNs or infinities.

Returns:

this object.

Throws:

JSONException - if an error occurs

remove

public java.lang.Object remove(java.lang.String name)

Removes the named mapping if it exists; does nothing otherwise.

Parameters:

name - the name of the property

Returns:

the value previously mapped by name, or null if there was no such mapping.

isNull

public boolean isNull(java.lang.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 property

Returns:

true if this object has no mapping for name

has

public boolean has(java.lang.String name)

Returns true if this object has a mapping for name. The mapping may be NULL.

Parameters:

name - the name of the property

Returns:

true if this object has a mapping for name

get

public java.lang.Object get(java.lang.String name)
                     throws JSONException

Returns the value mapped by name.

Parameters:

name - the name of the property

Returns:

the value

Throws:

JSONException - if no such mapping exists.

opt

public java.lang.Object opt(java.lang.String name)

Returns the value mapped by name, or null if no such mapping exists.

Parameters:

name - the name of the property

Returns:

the value or null

getBoolean

public boolean getBoolean(java.lang.String name)
                   throws JSONException

Returns the value mapped by name if it exists and is a boolean or can be coerced to a boolean.

Parameters:

name - the name of the property

Returns:

the value

Throws:

JSONException - if the mapping doesn't exist or cannot be coerced to a boolean.

optBoolean

public boolean optBoolean(java.lang.String name)

Returns the value mapped by name if it exists and is a boolean or can be coerced to a boolean. Returns false otherwise.

Parameters:

name - the name of the property

Returns:

the value or null

optBoolean

public boolean optBoolean(java.lang.String name,
                          boolean fallback)

Returns the value mapped by name if it exists and is a boolean or can be coerced to a boolean. Returns fallback otherwise.

Parameters:

name - the name of the property

fallback - a fallback value

Returns:

the value or fallback

getDouble

public double getDouble(java.lang.String name)
                 throws JSONException

Returns the value mapped by name if it exists and is a double or can be coerced to a double.

Parameters:

name - the name of the property

Returns:

the value

Throws:

JSONException - if the mapping doesn't exist or cannot be coerced to a double.

optDouble

public double optDouble(java.lang.String name)

Returns the value mapped by name if it exists and is a double or can be coerced to a double. Returns NaN otherwise.

Parameters:

name - the name of the property

Returns:

the value or NaN

optDouble

public double optDouble(java.lang.String name,
                        double fallback)

Returns the value mapped by name if it exists and is a double or can be coerced to a double. Returns fallback otherwise.

Parameters:

name - the name of the property

fallback - a fallback value

Returns:

the value or fallback

getInt

public int getInt(java.lang.String name)
           throws JSONException

Returns the value mapped by name if it exists and is an int or can be coerced to an int.

Parameters:

name - the name of the property

Returns:

the value

Throws:

JSONException - if the mapping doesn't exist or cannot be coerced to an int.

optInt

public int optInt(java.lang.String name)

Returns the value mapped by name if it exists and is an int or can be coerced to an int. Returns 0 otherwise.

Parameters:

name - the name of the property

Returns:

the value of 0

optInt

public int optInt(java.lang.String name,
                  int fallback)

Returns the value mapped by name if it exists and is an int or can be coerced to an int. Returns fallback otherwise.

Parameters:

name - the name of the property

fallback - a fallback value

Returns:

the value or fallback

getLong

public long getLong(java.lang.String name)
             throws JSONException

Returns the value mapped by name if it exists and is a long or can be coerced to a long. Note that JSON represents numbers as doubles, so this is lossy; use strings to transfer numbers over JSON.

Parameters:

name - the name of the property

Returns:

the value

Throws:

JSONException - if the mapping doesn't exist or cannot be coerced to a long.

optLong

public long optLong(java.lang.String name)

Returns the value mapped by name if it exists and is a long or can be coerced to a long. Returns 0 otherwise. Note that JSON represents numbers as doubles, so this is lossy; use strings to transfer numbers via JSON.

Parameters:

name - the name of the property

Returns:

the value or 0L

optLong

public long optLong(java.lang.String name,
                    long fallback)

Returns the value mapped by name if it exists and is a long or can be coerced to a long. Returns fallback otherwise. Note that JSON represents numbers as doubles, so this is lossy; use strings to transfer numbers over JSON.

Parameters:

name - the name of the property

fallback - a fallback value

Returns:

the value or fallback

getString

public java.lang.String getString(java.lang.String name)
                           throws JSONException

Returns the value mapped by name if it exists, coercing it if necessary.

Parameters:

name - the name of the property

Returns:

the value

Throws:

JSONException - if no such mapping exists.

optString

public java.lang.String optString(java.lang.String name)

Returns the value mapped by name if it exists, coercing it if necessary. Returns the empty string if no such mapping exists.

Parameters:

name - the name of the property

Returns:

the value or an empty string

optString

public java.lang.String optString(java.lang.String name,
                                  java.lang.String fallback)

Returns the value mapped by name if it exists, coercing it if necessary. Returns fallback if no such mapping exists.

Parameters:

name - the name of the property

fallback - a fallback value

Returns:

the value or fallback

getJSONArray

public JSONArray getJSONArray(java.lang.String name)
                       throws JSONException

Returns the value mapped by name if it exists and is a JSONArray.

Parameters:

name - the name of the property

Returns:

the value

Throws:

JSONException - if the mapping doesn't exist or is not a JSONArray.

optJSONArray

public JSONArray optJSONArray(java.lang.String name)

Returns the value mapped by name if it exists and is a JSONArray. Returns null otherwise.

Parameters:

name - the name of the property

Returns:

the value or null

getJSONObject

public JSONObject getJSONObject(java.lang.String name)
                         throws JSONException

Returns the value mapped by name if it exists and is a JSONObject.

Parameters:

name - the name of the property

Returns:

the value

Throws:

JSONException - if the mapping doesn't exist or is not a JSONObject.

optJSONObject

public JSONObject optJSONObject(java.lang.String name)

Returns the value mapped by name if it exists and is a JSONObject. Returns null otherwise.

Parameters:

name - the name of the property

Returns:

the value or null

toJSONArray

public JSONArray toJSONArray(JSONArray names)

Returns an array with the values corresponding to names. The array contains null for names that aren't mapped. This method returns null if names is either null or empty.

Parameters:

names - the names of the properties

Returns:

the array

keys

public java.util.Iterator keys()

Returns an iterator of the String names in this object. The returned iterator supports remove, which will remove the corresponding mapping from this object. If this object is modified after the iterator is returned, the iterator's behavior is undefined. The order of the keys is undefined.

Returns:

the keys

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 array

toString

public java.lang.String toString()

Encodes this object as a compact JSON string, such as:

{"query":"Pizza","locations":[94043,90210]}

Overrides:

toString in class java.lang.Object

Returns:

a string representation of the object.

toString

public java.lang.String toString(int indentSpaces)

Encodes this object as a human-readable JSON string for debugging, such as:

 {
     "query": "Pizza",
     "locations": [
         94043,
         90210
     ]
 }
 

Parameters:

indentSpaces - the number of spaces to indent for each level of nesting.

Returns:

a string representation of the object.

Throws:

java.lang.RuntimeException - if an error occurs

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

numberToString

public static java.lang.String numberToString(java.lang.Number number)
                                       throws JSONException

Encodes the number as a JSON string.

Parameters:

number - a finite value. May not be NaNs or infinities.

Returns:

the encoded value

Throws:

JSONException - if an error occurs

quote

public static java.lang.String quote(java.lang.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 value

wrap

public static java.lang.Object wrap(java.lang.Object o)

Wraps the given object if necessary.

If the object is null or , returns NULL. If the object is a JSONArray or JSONObject, no wrapping is necessary. If the object is NULL, no wrapping is necessary. If the object is an array or Collection, returns an equivalent JSONArray. If the object is a Map, returns an equivalent JSONObject. If the object is a primitive wrapper type or String, returns the object. Otherwise if the object is from a java package, returns the result of toString. If wrapping fails, returns null.

Parameters:

o - the object to wrap

Returns:

the wrapped object