org.codehaus.jackson
Class JsonNode

java.lang.Object
  extended by org.codehaus.jackson.JsonNode
All Implemented Interfaces:
Iterable<JsonNode>
Direct Known Subclasses:
BaseJsonNode

public abstract class JsonNode
extends Object
implements Iterable<JsonNode>

Base class for all JSON nodes, which form the basis of JSON Tree Model that Jackson implements. One way to think of these nodes is to consider them similar to DOM nodes in XML DOM trees.

As a general design rule, most accessors ("getters") are included in this base class, to allow for traversing structure without type casts. Most mutators, however, need to be accessed through specific sub-classes. This seems sensible because proper type information is generally available when building or modifying trees, but less often when reading a tree (newly built from parsed JSON content).

Actual concrete sub-classes can be found from package org.codehaus.jackson.node, which is in 'mapper' jar (whereas this class is in 'core' jar, since it is declared as nominal type for operations in ObjectCodec


Field Summary
protected static List<JsonNode> NO_NODES
           
protected static List<String> NO_STRINGS
           
 
Constructor Summary
protected JsonNode()
           
 
Method Summary
abstract  JsonToken asToken()
          Method that can be used for efficient type detection when using stream abstraction for traversing nodes.
abstract  boolean equals(Object o)
          Equality for node objects is defined as full (deep) value equality.
abstract  JsonNode findParent(String fieldName)
          Method for finding a JSON Object that contains specified field, within this node or its descendants.
 List<JsonNode> findParents(String fieldName)
          Method for finding a JSON Object that contains specified field, within this node or its descendants.
abstract  List<JsonNode> findParents(String fieldName, List<JsonNode> foundSoFar)
           
abstract  JsonNode findPath(String fieldName)
          Method similar to findValue(java.lang.String), but that will return a "missing node" instead of null if no field is found.
abstract  JsonNode findValue(String fieldName)
          Method for finding a JSON Object field with specified name in this node or its child nodes, and returning value it has.
 List<JsonNode> findValues(String fieldName)
          Method for finding JSON Object fields with specified name, and returning found ones as a List.
abstract  List<JsonNode> findValues(String fieldName, List<JsonNode> foundSoFar)
           
 List<String> findValuesAsText(String fieldName)
          Similar to findValues(java.lang.String), but will additionally convert values into Strings, calling getValueAsText().
abstract  List<String> findValuesAsText(String fieldName, List<String> foundSoFar)
           
 JsonNode get(int index)
          Method for accessing value of the specified element of an array node.
 JsonNode get(String fieldName)
          Method for accessing value of the specified field of an object node.
 BigInteger getBigIntegerValue()
           
 byte[] getBinaryValue()
          Method to use for accessing binary content of binary nodes (nodes for which isBinary() returns true); or for Text Nodes (ones for which getTextValue() returns non-null value), to read decoded base64 data.
 boolean getBooleanValue()
          Method to use for accessing JSON boolean values (value literals 'true' and 'false').
 BigDecimal getDecimalValue()
           
 double getDoubleValue()
           
 Iterator<JsonNode> getElements()
          Method for accessing all value nodes of this Node, iff this node is a JSON Array or Object node.
 JsonNode getElementValue(int index)
          Deprecated. Use get(int) instead.
 Iterator<String> getFieldNames()
          Method for accessing names of all fields for this Node, iff this node is a JSON Object node.
 JsonNode getFieldValue(String fieldName)
          Deprecated. Use get(String) instead.
 int getIntValue()
          Returns integer value for this node, if and only if this node is numeric (isNumber() returns true).
 long getLongValue()
           
abstract  JsonParser.NumberType getNumberType()
          If this node is a numeric type (as per isNumber()), returns native type that node uses to store the numeric value.
 Number getNumberValue()
          Returns numeric value for this node, if and only if this node is numeric (isNumber() returns true); otherwise returns null
 JsonNode getPath(int index)
          Deprecated. Use path(int) instead
 JsonNode getPath(String fieldName)
          Deprecated. Use path(String) instead
 String getTextValue()
          Method to use for accessing String values.
 boolean getValueAsBoolean()
          Method that will try to convert value of this node to a Java boolean.
 boolean getValueAsBoolean(boolean defaultValue)
          Method that will try to convert value of this node to a Java boolean.
 double getValueAsDouble()
          Method that will try to convert value of this node to a Java double.
 double getValueAsDouble(double defaultValue)
          Method that will try to convert value of this node to a Java double.
 int getValueAsInt()
          Method that will try to convert value of this node to a Java int.
 int getValueAsInt(int defaultValue)
          Method that will try to convert value of this node to a Java int.
 long getValueAsLong()
          Method that will try to convert value of this node to a Java long.
 long getValueAsLong(long defaultValue)
          Method that will try to convert value of this node to a Java long.
abstract  String getValueAsText()
          Method that will return valid String representation of the container value, if the node is a value node (method isValueNode() returns true), otherwise null.
 boolean has(int index)
          Method that allows checking whether this node is JSON Array node and contains a value for specified index If this is the case (including case of specified indexing having null as value), returns true; otherwise returns false.
 boolean has(String fieldName)
          Method that allows checking whether this node is JSON Object node and contains value for specified property.
 boolean isArray()
           
 boolean isBigDecimal()
           
 boolean isBigInteger()
           
 boolean isBinary()
          Method that can be used to check if this node represents binary data (Base64 encoded).
 boolean isBoolean()
          Method that can be used to check if this node was created from Json boolean value (literals "true" and "false").
 boolean isContainerNode()
          Method that returns true for container nodes: Arrays and Objects.
 boolean isDouble()
           
 boolean isFloatingPointNumber()
           
 boolean isInt()
           
 boolean isIntegralNumber()
           
 boolean isLong()
           
 boolean isMissingNode()
          Method that returns true for "virtual" nodes which represent missing entries constructed by path accessor methods when there is no actual node matching given criteria.
 boolean isNull()
          Method that can be used to check if this node was created from Json liternal null value.
 boolean isNumber()
           
 boolean isObject()
           
 boolean isPojo()
          Method that can be used to check if the node is a wrapper for a POJO ("Plain Old Java Object" aka "bean".
 boolean isTextual()
           
 boolean isValueNode()
          Method that returns true for all value nodes: ones that are not containers, and that do not represent "missing" nodes in the path.
 Iterator<JsonNode> iterator()
          Same as calling getElements(); implemented so that convenience "for-each" loop can be used for looping over elements of JSON Array constructs.
abstract  JsonNode path(int index)
          This method is similar to get(int), except that instead of returning null if no such element exists (due to index being out of range, or this node not being an array), a "missing node" (node that returns true for isMissingNode()) will be returned.
abstract  JsonNode path(String fieldName)
          This method is similar to get(String), except that instead of returning null if no such value exists (due to this node not being an object, or object not having value for the specified field), a "missing node" (node that returns true for isMissingNode()) will be returned.
 int size()
          Method that returns number of child nodes this node contains: for Array nodes, number of child elements, for Object nodes, number of fields, and for all other nodes 0.
abstract  String toString()
           Note: marked as abstract to ensure all implementation classes define it properly.
abstract  JsonParser traverse()
          Method for constructing a JsonParser instance for iterating over contents of the tree that this node is root of.
abstract  void writeTo(JsonGenerator jg)
          Deprecated. Use methods that are part of JsonGenerator or ObjectMapper instead.
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

NO_NODES

protected static final List<JsonNode> NO_NODES

NO_STRINGS

protected static final List<String> NO_STRINGS
Constructor Detail

JsonNode

protected JsonNode()
Method Detail

isValueNode

public boolean isValueNode()
Method that returns true for all value nodes: ones that are not containers, and that do not represent "missing" nodes in the path. Such value nodes represent String, Number, Boolean and null values from JSON.

Note: one and only one of methods isValueNode(), isContainerNode() and isMissingNode() ever returns true for any given node.


isContainerNode

public boolean isContainerNode()
Method that returns true for container nodes: Arrays and Objects.

Note: one and only one of methods isValueNode(), isContainerNode() and isMissingNode() ever returns true for any given node.


isMissingNode

public boolean isMissingNode()
Method that returns true for "virtual" nodes which represent missing entries constructed by path accessor methods when there is no actual node matching given criteria.

Note: one and only one of methods isValueNode(), isContainerNode() and isMissingNode() ever returns true for any given node.


isArray

public boolean isArray()
Returns:
True if this node represents Json Array

isObject

public boolean isObject()
Returns:
True if this node represents Json Object

isPojo

public boolean isPojo()
Method that can be used to check if the node is a wrapper for a POJO ("Plain Old Java Object" aka "bean". Returns true only for instances of POJONode.

Returns:
True if this node wraps a POJO

isNumber

public boolean isNumber()
Returns:
True if this node represents a numeric Json value

isIntegralNumber

public boolean isIntegralNumber()
Returns:
True if this node represents an integral (integer) numeric Json value

isFloatingPointNumber

public boolean isFloatingPointNumber()
Returns:
True if this node represents a non-integral numeric Json value

isInt

public boolean isInt()
Returns:
True if this node represents an integral numeric Json value that withs in Java int value space

isLong

public boolean isLong()
Returns:
True if this node represents an integral numeric Json value that fits in Java long value space (but not int value space, i.e. isInt() returns false)

isDouble

public boolean isDouble()

isBigDecimal

public boolean isBigDecimal()

isBigInteger

public boolean isBigInteger()

isTextual

public boolean isTextual()

isBoolean

public boolean isBoolean()
Method that can be used to check if this node was created from Json boolean value (literals "true" and "false").


isNull

public boolean isNull()
Method that can be used to check if this node was created from Json liternal null value.


isBinary

public boolean isBinary()
Method that can be used to check if this node represents binary data (Base64 encoded). Although this will be externally written as Json String value, isTextual() will return false if this method returns true.

Returns:
True if this node represents base64 encoded binary data

asToken

public abstract JsonToken asToken()
Method that can be used for efficient type detection when using stream abstraction for traversing nodes. Will return the first JsonToken that equivalent stream event would produce (for most nodes there is just one token but for structured/container types multiple)

Since:
1.3

getNumberType

public abstract JsonParser.NumberType getNumberType()
If this node is a numeric type (as per isNumber()), returns native type that node uses to store the numeric value.


getTextValue

public String getTextValue()
Method to use for accessing String values. Does NOT do any conversions for non-String value nodes; for non-String values (ones for which isTextual() returns false) null will be returned. For String values, null is never returned (but empty Strings may be)

Returns:
Textual value this node contains, iff it is a textual json node (comes from Json String value entry)

getBinaryValue

public byte[] getBinaryValue()
                      throws IOException
Method to use for accessing binary content of binary nodes (nodes for which isBinary() returns true); or for Text Nodes (ones for which getTextValue() returns non-null value), to read decoded base64 data. For other types of nodes, returns null.

Returns:
Binary data this node contains, iff it is a binary node; null otherwise
Throws:
IOException

getBooleanValue

public boolean getBooleanValue()
Method to use for accessing JSON boolean values (value literals 'true' and 'false'). For other types, always returns false.

Returns:
Textual value this node contains, iff it is a textual json node (comes from Json String value entry)

getNumberValue

public Number getNumberValue()
Returns numeric value for this node, if and only if this node is numeric (isNumber() returns true); otherwise returns null

Returns:
Number value this node contains, if any (null for non-number nodes).

getIntValue

public int getIntValue()
Returns integer value for this node, if and only if this node is numeric (isNumber() returns true). For other types returns 0. For floating-point numbers, value is truncated using default Java coercion, similar to how cast from double to int operates.

Returns:
Integer value this node contains, if any; 0 for non-number nodes.

getLongValue

public long getLongValue()

getDoubleValue

public double getDoubleValue()

getDecimalValue

public BigDecimal getDecimalValue()

getBigIntegerValue

public BigInteger getBigIntegerValue()

get

public JsonNode get(int index)
Method for accessing value of the specified element of an array node. For other nodes, null is always returned.

For array nodes, index specifies exact location within array and allows for efficient iteration over child elements (underlying storage is guaranteed to be efficiently indexable, i.e. has random-access to elements). If index is less than 0, or equal-or-greater than node.size(), null is returned; no exception is thrown for any index.

Returns:
Node that represent value of the specified element, if this node is an array and has specified element. Null otherwise.

get

public JsonNode get(String fieldName)
Method for accessing value of the specified field of an object node. If this node is not an object (or it does not have a value for specified field name), or if there is no field with such name, null is returned.

Returns:
Node that represent value of the specified field, if this node is an object and has value for the specified field. Null otherwise.

getValueAsText

public abstract String getValueAsText()
Method that will return valid String representation of the container value, if the node is a value node (method isValueNode() returns true), otherwise null.

Note: to serialize nodes of any type, you should call toString() instead.


getValueAsInt

public int getValueAsInt()
Method that will try to convert value of this node to a Java int. Numbers are coerced using default Java rules; booleans convert to 0 (false) and 1 (true), and Strings are parsed using default Java language integer parsing rules.

If representation can not be converted to an int (including structured types like Objects and Arrays), default value of 0 will be returned; no exceptions are thrown.

Since:
1.6

getValueAsInt

public int getValueAsInt(int defaultValue)
Method that will try to convert value of this node to a Java int. Numbers are coerced using default Java rules; booleans convert to 0 (false) and 1 (true), and Strings are parsed using default Java language integer parsing rules.

If representation can not be converted to an int (including structured types like Objects and Arrays), specified defaultValue will be returned; no exceptions are thrown.

Since:
1.6

getValueAsLong

public long getValueAsLong()
Method that will try to convert value of this node to a Java long. Numbers are coerced using default Java rules; booleans convert to 0 (false) and 1 (true), and Strings are parsed using default Java language integer parsing rules.

If representation can not be converted to an long (including structured types like Objects and Arrays), default value of 0 will be returned; no exceptions are thrown.

Since:
1.6

getValueAsLong

public long getValueAsLong(long defaultValue)
Method that will try to convert value of this node to a Java long. Numbers are coerced using default Java rules; booleans convert to 0 (false) and 1 (true), and Strings are parsed using default Java language integer parsing rules.

If representation can not be converted to an long (including structured types like Objects and Arrays), specified defaultValue will be returned; no exceptions are thrown.

Since:
1.6

getValueAsDouble

public double getValueAsDouble()
Method that will try to convert value of this node to a Java double. Numbers are coerced using default Java rules; booleans convert to 0.0 (false) and 1.0 (true), and Strings are parsed using default Java language integer parsing rules.

If representation can not be converted to an int (including structured types like Objects and Arrays), default value of 0.0 will be returned; no exceptions are thrown.

Since:
1.6

getValueAsDouble

public double getValueAsDouble(double defaultValue)
Method that will try to convert value of this node to a Java double. Numbers are coerced using default Java rules; booleans convert to 0.0 (false) and 1.0 (true), and Strings are parsed using default Java language integer parsing rules.

If representation can not be converted to an int (including structured types like Objects and Arrays), specified defaultValue will be returned; no exceptions are thrown.

Since:
1.6

getValueAsBoolean

public boolean getValueAsBoolean()
Method that will try to convert value of this node to a Java boolean. JSON booleans map naturally; integer numbers other than 0 map to true, and 0 maps to false and Strings 'true' and 'false' map to corresponding values.

If representation can not be converted to a boolean value (including structured types like Objects and Arrays), default value of false will be returned; no exceptions are thrown.

Since:
1.7

getValueAsBoolean

public boolean getValueAsBoolean(boolean defaultValue)
Method that will try to convert value of this node to a Java boolean. JSON booleans map naturally; integer numbers other than 0 map to true, and 0 maps to false and Strings 'true' and 'false' map to corresponding values.

If representation can not be converted to a boolean value (including structured types like Objects and Arrays), specified defaultValue will be returned; no exceptions are thrown.

Since:
1.7

has

public boolean has(String fieldName)
Method that allows checking whether this node is JSON Object node and contains value for specified property. If this is the case (including properties with explicit null values), returns true; otherwise returns false.

This method is equivalent to:

   node.get(fieldName) != null
(since return value of get() is node, not value node contains)

Parameters:
fieldName - Name of element to check
Returns:
True if this node is a JSON Object node, and has a property entry with specified name (with any value, including null value)
Since:
1.6

has

public boolean has(int index)
Method that allows checking whether this node is JSON Array node and contains a value for specified index If this is the case (including case of specified indexing having null as value), returns true; otherwise returns false.

Note: array element indexes are 0-based.

This method is equivalent to:

   node.get(index) != null

Parameters:
index - Index to check
Returns:
True if this node is a JSON Object node, and has a property entry with specified name (with any value, including null value)
Since:
1.6

findValue

public abstract JsonNode findValue(String fieldName)
Method for finding a JSON Object field with specified name in this node or its child nodes, and returning value it has. If no matching field is found in this node or its descendants, returns null.

Parameters:
fieldName - Name of field to look for
Returns:
Value of first matching node found, if any; null if none
Since:
1.6

findValues

public final List<JsonNode> findValues(String fieldName)
Method for finding JSON Object fields with specified name, and returning found ones as a List. Note that sub-tree search ends if a field is found, so possible children of result nodes are not included. If no matching fields are found in this node or its descendants, returns an empty List.

Parameters:
fieldName - Name of field to look for
Since:
1.6

findValuesAsText

public final List<String> findValuesAsText(String fieldName)
Similar to findValues(java.lang.String), but will additionally convert values into Strings, calling getValueAsText().

Since:
1.6

findPath

public abstract JsonNode findPath(String fieldName)
Method similar to findValue(java.lang.String), but that will return a "missing node" instead of null if no field is found. Missing node is a specific kind of node for which isMissingNode() returns true; and all value access methods return empty or missing value.

Parameters:
fieldName - Name of field to look for
Returns:
Value of first matching node found; or if not found, a "missing node" (non-null instance that has no value)
Since:
1.6

findParent

public abstract JsonNode findParent(String fieldName)
Method for finding a JSON Object that contains specified field, within this node or its descendants. If no matching field is found in this node or its descendants, returns null.

Parameters:
fieldName - Name of field to look for
Returns:
Value of first matching node found, if any; null if none
Since:
1.6

findParents

public final List<JsonNode> findParents(String fieldName)
Method for finding a JSON Object that contains specified field, within this node or its descendants. If no matching field is found in this node or its descendants, returns null.

Parameters:
fieldName - Name of field to look for
Returns:
Value of first matching node found, if any; null if none
Since:
1.6

findValues

public abstract List<JsonNode> findValues(String fieldName,
                                          List<JsonNode> foundSoFar)

findValuesAsText

public abstract List<String> findValuesAsText(String fieldName,
                                              List<String> foundSoFar)

findParents

public abstract List<JsonNode> findParents(String fieldName,
                                           List<JsonNode> foundSoFar)

getFieldValue

@Deprecated
public final JsonNode getFieldValue(String fieldName)
Deprecated. Use get(String) instead.

Alias for get(String).


getElementValue

@Deprecated
public final JsonNode getElementValue(int index)
Deprecated. Use get(int) instead.

Alias for get(int).


size

public int size()
Method that returns number of child nodes this node contains: for Array nodes, number of child elements, for Object nodes, number of fields, and for all other nodes 0.

Returns:
For non-container nodes returns 0; for arrays number of contained elements, and for objects number of fields.

iterator

public final Iterator<JsonNode> iterator()
Same as calling getElements(); implemented so that convenience "for-each" loop can be used for looping over elements of JSON Array constructs.

Specified by:
iterator in interface Iterable<JsonNode>

getElements

public Iterator<JsonNode> getElements()
Method for accessing all value nodes of this Node, iff this node is a JSON Array or Object node. In case of Object node, field names (keys) are not included, only values. For other types of nodes, returns empty iterator.


getFieldNames

public Iterator<String> getFieldNames()
Method for accessing names of all fields for this Node, iff this node is a JSON Object node.


path

public abstract JsonNode path(String fieldName)
This method is similar to get(String), except that instead of returning null if no such value exists (due to this node not being an object, or object not having value for the specified field), a "missing node" (node that returns true for isMissingNode()) will be returned. This allows for convenient and safe chained access via path calls.


getPath

@Deprecated
public final JsonNode getPath(String fieldName)
Deprecated. Use path(String) instead

Alias of path(String).


path

public abstract JsonNode path(int index)
This method is similar to get(int), except that instead of returning null if no such element exists (due to index being out of range, or this node not being an array), a "missing node" (node that returns true for isMissingNode()) will be returned. This allows for convenient and safe chained access via path calls.


getPath

@Deprecated
public final JsonNode getPath(int index)
Deprecated. Use path(int) instead

Alias of path(int).


writeTo

@Deprecated
public abstract void writeTo(JsonGenerator jg)
                      throws IOException,
                             JsonGenerationException
Deprecated. Use methods that are part of JsonGenerator or ObjectMapper instead.

Method that can be called to serialize this node and all of its descendants using specified JSON generator.

Throws:
IOException
JsonGenerationException

traverse

public abstract JsonParser traverse()
Method for constructing a JsonParser instance for iterating over contents of the tree that this node is root of. Functionally equivalent to first serializing tree using writeTo(org.codehaus.jackson.JsonGenerator) and then re-parsing but much more efficient.


toString

public abstract String toString()

Note: marked as abstract to ensure all implementation classes define it properly.

Overrides:
toString in class Object

equals

public abstract boolean equals(Object o)
Equality for node objects is defined as full (deep) value equality. This means that it is possible to compare complete JSON trees for equality by comparing equality of root nodes.

Note: marked as abstract to ensure all implementation classes define it properly and not rely on definition from Object.

Overrides:
equals in class Object