Class JsonValue

java.lang.Object
com.restfb.json.JsonValue
All Implemented Interfaces:
Serializable
Direct Known Subclasses:
JsonArray, JsonObject

public abstract class JsonValue
extends Object
implements Serializable
Represents a JSON value. This can be a JSON object, an array, a number, a string, or one of the literals true, false, and null.

The literals true, false, and null are represented by the constants Json.TRUE, Json.FALSE, and Json.NULL.

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

Instances that represent JSON numbers, strings and boolean values can be created using the static factory methods Json.value(String), Json.value(long), Json.value(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 the type of a JSON value is known, 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.

See Also:
Serialized Form
  • Field Summary

    Fields 
    Modifier and Type Field Description
    protected static String ARRAY_IS_NULL  
    protected static String NAME_IS_NULL  
    protected static String OBJECT_IS_NULL  
    protected static String STRING_IS_NULL  
    protected static String VALUE_IS_NULL  
  • Method Summary

    Modifier and Type Method Description
    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.
    String asString()
    Returns this JSON value as String, assuming that this value represents a JSON string.
    boolean equals​(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.
    String toString()
    Returns the JSON string for this value in its minimal form, without any additional whitespace.
    String toString​(WriterConfig config)
    Returns the JSON string for this value using the given formatting.
    void writeTo​(Writer writer)
    Writes the JSON representation of this value to the given writer in its minimal form, without any additional whitespace.
    void writeTo​(Writer writer, WriterConfig config)
    Writes the JSON representation of this value to the given writer using the given formatting.

    Methods inherited from class java.lang.Object

    clone, finalize, getClass, notify, notifyAll, wait, wait, wait
  • Field Details

  • Method Details

    • 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:
      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:
      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:
      UnsupportedOperationException - if this value is not a JSON number
      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:
      UnsupportedOperationException - if this value is not a JSON number
      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:
      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:
      UnsupportedOperationException - if this value is not a JSON number
    • asString

      public 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:
      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:
      UnsupportedOperationException - if this value is neither true or false
    • writeTo

      public void writeTo​(Writer writer) throws IOException
      Writes the JSON representation of this value to the given writer in its minimal form, without any additional whitespace.

      Writing performance can be improved by using a BufferedWriter.

      Parameters:
      writer - the writer to write this value to
      Throws:
      IOException - if an I/O error occurs in the writer
    • writeTo

      public void writeTo​(Writer writer, WriterConfig config) throws IOException
      Writes the JSON representation of this value to the given writer using the given formatting.

      Writing performance can be improved by using a BufferedWriter.

      Parameters:
      writer - the writer to write this value to
      config - a configuration that controls the formatting or null for the minimal form
      Throws:
      IOException - if an I/O error occurs in the writer
    • toString

      public 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 Json.parse(String) and to create a value that is equal to this object.
      Overrides:
      toString in class Object
      Returns:
      a JSON string that represents this value
    • toString

      public String toString​(WriterConfig config)
      Returns the JSON string for this value using the given formatting.
      Parameters:
      config - a configuration that controls the formatting or null for the minimal form
      Returns:
      a JSON string that represents this value
    • equals

      public boolean equals​(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 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 Object