org.eclipse.rap.json
Class JsonValue

java.lang.Object
  org.eclipse.rap.json.JsonValue

All Implemented Interfaces:

java.io.Serializable

Direct Known Subclasses:

JsonArray, JsonObject

public abstract class JsonValue
extends java.lang.Object
implements java.io.Serializable

Represents a JSON value. According to RFC 4627, a JSON value must be an object, an array, a number, a string, or one of the literal names true, false, and null.

The literal names true, false, and null are represented by the constants TRUE, FALSE, and NULL.

JSON objects and arrays are represented by the subtypes JsonObject and JsonArray. Instances of these types can be created using the public constructors.

Instances for JSON numbers and strings can be created using the static factory methods valueOf(String), valueOf(long), valueOf(double) , etc.

In order to find out whether an instance of this class is of a certain type, the methods isObject(), isArray(), isString(), isNumber() etc. can be used.

If there is no doubt about the type of a JSON value, one of the methods asObject(), asArray(), asString(), asInt(), etc. can be used to get this value directly in the appropriate target type.

This class is not supposed to be extended by clients.

Since:

2.1

See Also:

Serialized Form

Field Summary

static JsonValue	FALSE Represents the JSON literal false.
static JsonValue	NULL The JSON literal null.
static JsonValue	TRUE Represents the JSON literal true.

Method Summary

JsonArray	asArray() Returns this JSON value as JsonArray, assuming that this value represents a JSON array.
boolean	asBoolean() Returns this JSON value as a boolean value, assuming that this value is either true or false.
double	asDouble() Returns this JSON value as a double value, assuming that this value represents a JSON number.
float	asFloat() Returns this JSON value as a float value, assuming that this value represents a JSON number.
int	asInt() Returns this JSON value as an int value, assuming that this value represents a JSON number that can be interpreted as Java int.
long	asLong() Returns this JSON value as a long value, assuming that this value represents a JSON number that can be interpreted as Java long.
JsonObject	asObject() Returns this JSON value as JsonObject, assuming that this value represents a JSON object.
java.lang.String	asString() Returns this JSON value as String, assuming that this value represents a JSON string.
boolean	equals(java.lang.Object object) Indicates whether some other object is "equal to" this one according to the contract specified in Object.equals(Object).
int	hashCode()
boolean	isArray() Detects whether this value represents a JSON array.
boolean	isBoolean() Detects whether this value represents a boolean value.
boolean	isFalse() Detects whether this value represents the JSON literal false.
boolean	isNull() Detects whether this value represents the JSON literal null.
boolean	isNumber() Detects whether this value represents a JSON number.
boolean	isObject() Detects whether this value represents a JSON object.
boolean	isString() Detects whether this value represents a JSON string.
boolean	isTrue() Detects whether this value represents the JSON literal true.
static JsonValue	readFrom(java.io.Reader reader) Reads a JSON value from the given reader.
static JsonValue	readFrom(java.lang.String text) Reads a JSON value from the given string.
java.lang.String	toString() Returns the JSON string for this value in its minimal form, without any additional whitespace.
static JsonValue	valueOf(boolean value) Returns a JsonValue instance that represents the given boolean value.
static JsonValue	valueOf(double value) Returns a JsonValue instance that represents the given double value.
static JsonValue	valueOf(float value) Returns a JsonValue instance that represents the given float value.
static JsonValue	valueOf(long value) Returns a JsonValue instance that represents the given long value.
static JsonValue	valueOf(java.lang.String string) Returns a JsonValue instance that represents the given string.
protected abstract void	write(org.eclipse.rap.json.JsonWriter writer)
void	writeTo(java.io.Writer writer) Writes the JSON representation for this object to the given writer.

Methods inherited from class java.lang.Object

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

Field Detail

TRUE

public static final JsonValue TRUE

Represents the JSON literal true.

FALSE

public static final JsonValue FALSE

Represents the JSON literal false.

NULL

public static final JsonValue NULL

The JSON literal null.

Method Detail

readFrom

public static JsonValue readFrom(java.io.Reader reader)
                          throws java.io.IOException

Reads a JSON value from the given reader.

Parameters:

reader - the reader to read the JSON value from

Returns:

the JSON value that has been read

Throws:

java.io.IOException - if an I/O error occurs in the reader

ParseException - if the input is not valid JSON

readFrom

public static JsonValue readFrom(java.lang.String text)

Reads a JSON value from the given string.

Parameters:

text - the string that contains the JSON value

Returns:

the JSON value that has been read

Throws:

ParseException - if the input is not valid JSON

valueOf

public static JsonValue valueOf(long value)

Returns a JsonValue instance that represents the given long value.

Parameters:

value - the value to get a JSON representation for

Returns:

a JSON value that represents the given value

valueOf

public static JsonValue valueOf(float value)

Returns a JsonValue instance that represents the given float value.

Parameters:

value - the value to get a JSON representation for

Returns:

a JSON value that represents the given value

valueOf

public static JsonValue valueOf(double value)

Returns a JsonValue instance that represents the given double value.

Parameters:

value - the value to get a JSON representation for

Returns:

a JSON value that represents the given value

valueOf

public static JsonValue valueOf(java.lang.String string)

Returns a JsonValue instance that represents the given string.

Parameters:

string - the string to get a JSON representation for

Returns:

a JSON value that represents the given string

valueOf

public static JsonValue valueOf(boolean value)

Returns a JsonValue instance that represents the given boolean value.

Parameters:

value - the value to get a JSON representation for

Returns:

a JSON value that represents the given value

isObject

public boolean isObject()

Detects whether this value represents a JSON object. If this is the case, this value is an instance of JsonObject.

Returns:

true if this value is an instance of JsonObject

isArray

public boolean isArray()

Detects whether this value represents a JSON array. If this is the case, this value is an instance of JsonArray.

Returns:

true if this value is an instance of JsonArray

isNumber

public boolean isNumber()

Detects whether this value represents a JSON number.

Returns:

true if this value represents a JSON number

isString

public boolean isString()

Detects whether this value represents a JSON string.

Returns:

true if this value represents a JSON string

isBoolean

public boolean isBoolean()

Detects whether this value represents a boolean value.

Returns:

true if this value represents either the JSON literal true or false

isTrue

public boolean isTrue()

Detects whether this value represents the JSON literal true.

Returns:

true if this value represents the JSON literal true

isFalse

public boolean isFalse()

Detects whether this value represents the JSON literal false.

Returns:

true if this value represents the JSON literal false

isNull

public boolean isNull()

Detects whether this value represents the JSON literal null.

Returns:

true if this value represents the JSON literal null

asObject

public JsonObject asObject()

Returns this JSON value as JsonObject, assuming that this value represents a JSON object. If this is not the case, an exception is thrown.

Returns:

a JSONObject for this value

Throws:

java.lang.UnsupportedOperationException - if this value is not a JSON object

asArray

public JsonArray asArray()

Returns this JSON value as JsonArray, assuming that this value represents a JSON array. If this is not the case, an exception is thrown.

Returns:

a JSONArray for this value

Throws:

java.lang.UnsupportedOperationException - if this value is not a JSON array

asInt

public int asInt()

Returns this JSON value as an int value, assuming that this value represents a JSON number that can be interpreted as Java int. If this is not the case, an exception is thrown.

To be interpreted as Java int, the JSON number must neither contain an exponent nor a fraction part. Moreover, the number must be in the Integer range.

Returns:

this value as int

Throws:

java.lang.UnsupportedOperationException - if this value is not a JSON number

java.lang.NumberFormatException - if this JSON number can not be interpreted as int value

asLong

public long asLong()

Returns this JSON value as a long value, assuming that this value represents a JSON number that can be interpreted as Java long. If this is not the case, an exception is thrown.

To be interpreted as Java long, the JSON number must neither contain an exponent nor a fraction part. Moreover, the number must be in the Long range.

Returns:

this value as long

Throws:

java.lang.UnsupportedOperationException - if this value is not a JSON number

java.lang.NumberFormatException - if this JSON number can not be interpreted as long value

asFloat

public float asFloat()

Returns this JSON value as a float value, assuming that this value represents a JSON number. If this is not the case, an exception is thrown.

If the JSON number is out of the Float range, Float.POSITIVE_INFINITY or Float.NEGATIVE_INFINITY is returned.

Returns:

this value as float

Throws:

java.lang.UnsupportedOperationException - if this value is not a JSON number

asDouble

public double asDouble()

Returns this JSON value as a double value, assuming that this value represents a JSON number. If this is not the case, an exception is thrown.

If the JSON number is out of the Double range, Double.POSITIVE_INFINITY or Double.NEGATIVE_INFINITY is returned.

Returns:

this value as double

Throws:

java.lang.UnsupportedOperationException - if this value is not a JSON number

asString

public java.lang.String asString()

Returns this JSON value as String, assuming that this value represents a JSON string. If this is not the case, an exception is thrown.

Returns:

the string represented by this value

Throws:

java.lang.UnsupportedOperationException - if this value is not a JSON string

asBoolean

public boolean asBoolean()

Returns this JSON value as a boolean value, assuming that this value is either true or false. If this is not the case, an exception is thrown.

Returns:

this value as boolean

Throws:

java.lang.UnsupportedOperationException - if this value is neither true or false

writeTo

public void writeTo(java.io.Writer writer)
             throws java.io.IOException

Writes the JSON representation for this object to the given writer.

Parameters:

writer - the writer to write this value to

Throws:

java.io.IOException - if an I/O error occurs in the writer

toString

public java.lang.String toString()

Returns the JSON string for this value in its minimal form, without any additional whitespace. The result is guaranteed to be a valid input for the method readFrom(String) and to create a value that is equal to this object.

Overrides:

toString in class java.lang.Object

Returns:

a JSON string that represents this value

equals

public boolean equals(java.lang.Object object)

Indicates whether some other object is "equal to" this one according to the contract specified in Object.equals(Object).

Two JsonValues are considered equal if and only if they represent the same JSON text. As a consequence, two given JsonObjects may be different even though they contain the same set of names with the same values, but in a different order.

Overrides:

equals in class java.lang.Object

Parameters:

object - the reference object with which to compare

Returns:

true if this object is the same as the object argument; false otherwise

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

write

protected abstract void write(org.eclipse.rap.json.JsonWriter writer)
                       throws java.io.IOException

Throws:

java.io.IOException