de.qfs.lib.json

Class JsonObject

java.lang.Object

de.qfs.lib.json.JsonValue

de.qfs.lib.json.JsonObject

All Implemented Interfaces:

java.io.Serializable, java.lang.Iterable<JsonObject.Member>

public class JsonObject
extends JsonValue
implements java.lang.Iterable<JsonObject.Member>

Represents a JSON object, a set of name/value pairs, where the names are strings and the values are JSON values.

Members can be added using the add(String, ...) methods which accept instances of JsonValue, strings, primitive numbers, and boolean values. To modify certain values of an object, use the set(String, ...) methods. Please note that the add methods are faster than set as they do not search for existing members. On the other hand, the add methods do not prevent adding multiple members with the same name. Duplicate names are discouraged but not prohibited by JSON.

Members can be accessed by their name using get(String). A list of all names can be obtained from the method names(). This class also supports iterating over the members in document order using an iterator() or an enhanced for loop:

 for (Member member : jsonObject) {
   String name = member.getName();
   JsonValue value = member.getValue();
   ...
 }
 

Even though JSON objects are unordered by definition, instances of this class preserve the order of members to allow processing in document order and to guarantee a predictable output.

Note that this class is not thread-safe. If multiple threads access a JsonObject instance concurrently, while at least one of these threads modifies the contents of this object, access to the instance must be synchronized externally. Failure to do so may lead to an inconsistent state.

This class is not supposed to be extended by clients.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	JsonObject.Member Represents a member of a JSON object, a pair of a name and a value.

Field Summary

Fields inherited from class de.qfs.lib.json.JsonValue

FALSE, NULL, TRUE

Constructor Summary

Constructors

Constructor and Description
JsonObject() Creates a new empty JsonObject.
JsonObject(JsonObject object) Creates a new JsonObject, initialized with the contents of the specified JSON object.

Method Summary

Modifier and Type	Method and Description
JsonObject	add(java.lang.String name, boolean value) Appends a new member to the end of this object, with the specified name and the JSON representation of the specified boolean value.
JsonObject	add(java.lang.String name, double value) Appends a new member to the end of this object, with the specified name and the JSON representation of the specified double value.
JsonObject	add(java.lang.String name, float value) Appends a new member to the end of this object, with the specified name and the JSON representation of the specified float value.
JsonObject	add(java.lang.String name, int value) Appends a new member to the end of this object, with the specified name and the JSON representation of the specified int value.
JsonObject	add(java.lang.String name, JsonValue value) Appends a new member to the end of this object, with the specified name and the specified JSON value.
JsonObject	add(java.lang.String name, long value) Appends a new member to the end of this object, with the specified name and the JSON representation of the specified long value.
JsonObject	add(java.lang.String name, java.lang.String value) Appends a new member to the end of this object, with the specified name and the JSON representation of the specified string.
JsonObject	asObject() Returns this JSON value as JsonObject, assuming that this value represents a JSON object.
boolean	contains(java.lang.String name) Checks if a specified member is present as a child of this object.
JsonObject	deepMerge(JsonObject object) Copies all members of the specified object into this object.
boolean	equals(java.lang.Object obj) Indicates whether some other object is "equal to" this one according to the contract specified in Object.equals(Object).
JsonValue	get(java.lang.String name) Returns the value of the member with the specified name in this object.
boolean	getBoolean(java.lang.String name, boolean defaultValue) Returns the boolean value of the member with the specified name in this object.
double	getDouble(java.lang.String name, double defaultValue) Returns the double value of the member with the specified name in this object.
float	getFloat(java.lang.String name, float defaultValue) Returns the float value of the member with the specified name in this object.
int	getInt(java.lang.String name, int defaultValue) Returns the int value of the member with the specified name in this object.
long	getLong(java.lang.String name, long defaultValue) Returns the long value of the member with the specified name in this object.
JsonObject	getObject(java.lang.String name) Returns the JsonObject value of the member with the specified name in this object.
java.lang.String	getString(java.lang.String name, java.lang.String defaultValue) Returns the String value of the member with the specified name in this object.
int	hashCode()
boolean	isEmpty() Returns true if this object contains no members.
boolean	isObject() Detects whether this value represents a JSON object.
java.util.Iterator<JsonObject.Member>	iterator() Returns an iterator over the members of this object in document order.
JsonObject	merge(JsonObject object) Copies all members of the specified object into this object.
java.util.List<java.lang.String>	names() Returns a list of the names in this object in document order.
static JsonObject	readFrom(java.io.Reader reader) Deprecated. Use Json.parse(Reader).asObject() instead
static JsonObject	readFrom(java.lang.String string) Deprecated. Use Json.parse(String).asObject() instead
JsonObject	remove(java.lang.String name) Removes a member with the specified name from this object.
JsonObject	set(java.lang.String name, boolean value) Sets the value of the member with the specified name to the JSON representation of the specified boolean value.
JsonObject	set(java.lang.String name, double value) Sets the value of the member with the specified name to the JSON representation of the specified double value.
JsonObject	set(java.lang.String name, float value) Sets the value of the member with the specified name to the JSON representation of the specified float value.
JsonObject	set(java.lang.String name, int value) Sets the value of the member with the specified name to the JSON representation of the specified int value.
JsonObject	set(java.lang.String name, JsonValue value) Sets the value of the member with the specified name to the specified JSON value.
JsonObject	set(java.lang.String name, long value) Sets the value of the member with the specified name to the JSON representation of the specified long value.
JsonObject	set(java.lang.String name, java.lang.String value) Sets the value of the member with the specified name to the JSON representation of the specified string.
int	size() Returns the number of members (name/value pairs) in this object.
static JsonObject	unmodifiableObject(JsonObject object) Returns an unmodifiable JsonObject for the specified one.

Methods inherited from class de.qfs.lib.json.JsonValue

asArray, asBoolean, asDouble, asFloat, asInt, asLong, asString, isArray, isBoolean, isFalse, isNull, isNumber, isString, isTrue, toString, toString, valueOf, valueOf, valueOf, valueOf, valueOf, valueOf, writeTo, writeTo

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

JsonObject

public JsonObject()

Creates a new empty JsonObject.

JsonObject

public JsonObject(JsonObject object)

Creates a new JsonObject, initialized with the contents of the specified JSON object.

Parameters:

object - the JSON object to get the initial contents from, must not be null

Method Detail

readFrom

@Deprecated
public static JsonObject readFrom(java.io.Reader reader)
                                       throws java.io.IOException

Deprecated. Use Json.parse(Reader).asObject() instead

Reads a JSON object from the given reader.

Characters are read in chunks and buffered internally, therefore wrapping an existing reader in an additional BufferedReader does not improve reading performance.

Parameters:

reader - the reader to read the JSON object from

Returns:

the JSON object 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

java.lang.UnsupportedOperationException - if the input does not contain a JSON object

readFrom

@Deprecated
public static JsonObject readFrom(java.lang.String string)

Deprecated. Use Json.parse(String).asObject() instead

Reads a JSON object from the given string.

Parameters:

string - the string that contains the JSON object

Returns:

the JSON object that has been read

Throws:

ParseException - if the input is not valid JSON

java.lang.UnsupportedOperationException - if the input does not contain a JSON object

unmodifiableObject

public static JsonObject unmodifiableObject(JsonObject object)

Returns an unmodifiable JsonObject for the specified one. This method allows to provide read-only access to a JsonObject.

The returned JsonObject is backed by the given object and reflect changes that happen to it. Attempts to modify the returned JsonObject result in an UnsupportedOperationException.

Parameters:

object - the JsonObject for which an unmodifiable JsonObject is to be returned

Returns:

an unmodifiable view of the specified JsonObject

add

public JsonObject add(java.lang.String name,
                      int value)

Appends a new member to the end of this object, with the specified name and the JSON representation of the specified int value.

This method does not prevent duplicate names. Calling this method with a name that already exists in the object will append another member with the same name. In order to replace existing members, use the method set(name, value) instead. However, add is much faster than set (because it does not need to search for existing members). Therefore add should be preferred when constructing new objects.

Parameters:

name - the name of the member to add

value - the value of the member to add

Returns:

the object itself, to enable method chaining

add

public JsonObject add(java.lang.String name,
                      long value)

Appends a new member to the end of this object, with the specified name and the JSON representation of the specified long value.

This method does not prevent duplicate names. Calling this method with a name that already exists in the object will append another member with the same name. In order to replace existing members, use the method set(name, value) instead. However, add is much faster than set (because it does not need to search for existing members). Therefore add should be preferred when constructing new objects.

Parameters:

name - the name of the member to add

value - the value of the member to add

Returns:

the object itself, to enable method chaining

add

public JsonObject add(java.lang.String name,
                      float value)

Appends a new member to the end of this object, with the specified name and the JSON representation of the specified float value.

This method does not prevent duplicate names. Calling this method with a name that already exists in the object will append another member with the same name. In order to replace existing members, use the method set(name, value) instead. However, add is much faster than set (because it does not need to search for existing members). Therefore add should be preferred when constructing new objects.

Parameters:

name - the name of the member to add

value - the value of the member to add

Returns:

the object itself, to enable method chaining

add

public JsonObject add(java.lang.String name,
                      double value)

Appends a new member to the end of this object, with the specified name and the JSON representation of the specified double value.

This method does not prevent duplicate names. Calling this method with a name that already exists in the object will append another member with the same name. In order to replace existing members, use the method set(name, value) instead. However, add is much faster than set (because it does not need to search for existing members). Therefore add should be preferred when constructing new objects.

Parameters:

name - the name of the member to add

value - the value of the member to add

Returns:

the object itself, to enable method chaining

add

public JsonObject add(java.lang.String name,
                      boolean value)

Appends a new member to the end of this object, with the specified name and the JSON representation of the specified boolean value.

This method does not prevent duplicate names. Calling this method with a name that already exists in the object will append another member with the same name. In order to replace existing members, use the method set(name, value) instead. However, add is much faster than set (because it does not need to search for existing members). Therefore add should be preferred when constructing new objects.

Parameters:

name - the name of the member to add

value - the value of the member to add

Returns:

the object itself, to enable method chaining

add

public JsonObject add(java.lang.String name,
                      java.lang.String value)

Appends a new member to the end of this object, with the specified name and the JSON representation of the specified string.

This method does not prevent duplicate names. Calling this method with a name that already exists in the object will append another member with the same name. In order to replace existing members, use the method set(name, value) instead. However, add is much faster than set (because it does not need to search for existing members). Therefore add should be preferred when constructing new objects.

Parameters:

name - the name of the member to add

value - the value of the member to add

Returns:

the object itself, to enable method chaining

add

public JsonObject add(java.lang.String name,
                      JsonValue value)

Appends a new member to the end of this object, with the specified name and the specified JSON value.

This method does not prevent duplicate names. Calling this method with a name that already exists in the object will append another member with the same name. In order to replace existing members, use the method set(name, value) instead. However, add is much faster than set (because it does not need to search for existing members). Therefore add should be preferred when constructing new objects.

Parameters:

name - the name of the member to add

value - the value of the member to add, must not be null

Returns:

the object itself, to enable method chaining

set

public JsonObject set(java.lang.String name,
                      int value)

Sets the value of the member with the specified name to the JSON representation of the specified int value. If this object does not contain a member with this name, a new member is added at the end of the object. If this object contains multiple members with this name, only the last one is changed.

This method should only be used to modify existing objects. To fill a new object with members, the method add(name, value) should be preferred which is much faster (as it does not need to search for existing members).

Parameters:

name - the name of the member to replace

value - the value to set to the member

Returns:

the object itself, to enable method chaining

set

public JsonObject set(java.lang.String name,
                      long value)

Sets the value of the member with the specified name to the JSON representation of the specified long value. If this object does not contain a member with this name, a new member is added at the end of the object. If this object contains multiple members with this name, only the last one is changed.

This method should only be used to modify existing objects. To fill a new object with members, the method add(name, value) should be preferred which is much faster (as it does not need to search for existing members).

Parameters:

name - the name of the member to replace

value - the value to set to the member

Returns:

the object itself, to enable method chaining

set

public JsonObject set(java.lang.String name,
                      float value)

Sets the value of the member with the specified name to the JSON representation of the specified float value. If this object does not contain a member with this name, a new member is added at the end of the object. If this object contains multiple members with this name, only the last one is changed.

This method should only be used to modify existing objects. To fill a new object with members, the method add(name, value) should be preferred which is much faster (as it does not need to search for existing members).

Parameters:

name - the name of the member to add

value - the value of the member to add

Returns:

the object itself, to enable method chaining

set

public JsonObject set(java.lang.String name,
                      double value)

Sets the value of the member with the specified name to the JSON representation of the specified double value. If this object does not contain a member with this name, a new member is added at the end of the object. If this object contains multiple members with this name, only the last one is changed.

This method should only be used to modify existing objects. To fill a new object with members, the method add(name, value) should be preferred which is much faster (as it does not need to search for existing members).

Parameters:

name - the name of the member to add

value - the value of the member to add

Returns:

the object itself, to enable method chaining

set

public JsonObject set(java.lang.String name,
                      boolean value)

Sets the value of the member with the specified name to the JSON representation of the specified boolean value. If this object does not contain a member with this name, a new member is added at the end of the object. If this object contains multiple members with this name, only the last one is changed.

This method should only be used to modify existing objects. To fill a new object with members, the method add(name, value) should be preferred which is much faster (as it does not need to search for existing members).

Parameters:

name - the name of the member to add

value - the value of the member to add

Returns:

the object itself, to enable method chaining

set

public JsonObject set(java.lang.String name,
                      java.lang.String value)

Sets the value of the member with the specified name to the JSON representation of the specified string. If this object does not contain a member with this name, a new member is added at the end of the object. If this object contains multiple members with this name, only the last one is changed.

This method should only be used to modify existing objects. To fill a new object with members, the method add(name, value) should be preferred which is much faster (as it does not need to search for existing members).

Parameters:

name - the name of the member to add

value - the value of the member to add

Returns:

the object itself, to enable method chaining

set

public JsonObject set(java.lang.String name,
                      JsonValue value)

Sets the value of the member with the specified name to the specified JSON value. If this object does not contain a member with this name, a new member is added at the end of the object. If this object contains multiple members with this name, only the last one is changed.

This method should only be used to modify existing objects. To fill a new object with members, the method add(name, value) should be preferred which is much faster (as it does not need to search for existing members).

Parameters:

name - the name of the member to add

value - the value of the member to add, must not be null

Returns:

the object itself, to enable method chaining

remove

public JsonObject remove(java.lang.String name)

Removes a member with the specified name from this object. If this object contains multiple members with the given name, only the last one is removed. If this object does not contain a member with the specified name, the object is not modified.

Parameters:

name - the name of the member to remove

Returns:

the object itself, to enable method chaining

contains

public boolean contains(java.lang.String name)

Checks if a specified member is present as a child of this object. This will not test if this object contains the literal null, JsonValue.isNull() should be used for this purpose.

Parameters:

name - the name of the member to check for

Returns:

whether or not the member is present

merge

public JsonObject merge(JsonObject object)

Copies all members of the specified object into this object. When the specified object contains members with names that also exist in this object, the existing values in this object will be replaced by the corresponding values in the specified object.

Parameters:

object - the object to merge

Returns:

the object itself, to enable method chaining

deepMerge

public JsonObject deepMerge(JsonObject object)

Copies all members of the specified object into this object. When the specified object contains members with names that also exist in this object, the existing values in this object will be replaced by the corresponding values in the specified object, except for the case that both values are JsonObjects themselves, which will trigger another merge of these objects

Parameters:

object - the object to merge

Returns:

the object itself, to enable method chaining

get

public JsonValue get(java.lang.String name)

Returns the value of the member with the specified name in this object. If this object contains multiple members with the given name, this method will return the last one.

Parameters:

name - the name of the member whose value is to be returned

Returns:

the value of the last member with the specified name, or null if this object does not contain a member with that name

getObject

public JsonObject getObject(java.lang.String name)

Returns the JsonObject value of the member with the specified name in this object. If this object does not contain a member with this name, null is returned. If this object contains multiple members with the given name, the last one will be picked. If this member's value does not represent a JSON number or if it cannot be interpreted as Java int, an exception is thrown.

Parameters:

name - the name of the member whose value is to be returned

Returns:

the value of the last member with the specified name, or the given default value if this object does not contain a member with that name

getInt

public int getInt(java.lang.String name,
                  int defaultValue)

Returns the int value of the member with the specified name in this object. If this object does not contain a member with this name, the given default value is returned. If this object contains multiple members with the given name, the last one will be picked. If this member's value does not represent a JSON number or if it cannot be interpreted as Java int, an exception is thrown.

Parameters:

name - the name of the member whose value is to be returned

defaultValue - the value to be returned if the requested member is missing

Returns:

the value of the last member with the specified name, or the given default value if this object does not contain a member with that name

getLong

public long getLong(java.lang.String name,
                    long defaultValue)

Returns the long value of the member with the specified name in this object. If this object does not contain a member with this name, the given default value is returned. If this object contains multiple members with the given name, the last one will be picked. If this member's value does not represent a JSON number or if it cannot be interpreted as Java long, an exception is thrown.

Parameters:

name - the name of the member whose value is to be returned

defaultValue - the value to be returned if the requested member is missing

Returns:

the value of the last member with the specified name, or the given default value if this object does not contain a member with that name

getFloat

public float getFloat(java.lang.String name,
                      float defaultValue)

Returns the float value of the member with the specified name in this object. If this object does not contain a member with this name, the given default value is returned. If this object contains multiple members with the given name, the last one will be picked. If this member's value does not represent a JSON number or if it cannot be interpreted as Java float, an exception is thrown.

Parameters:

name - the name of the member whose value is to be returned

defaultValue - the value to be returned if the requested member is missing

Returns:

the value of the last member with the specified name, or the given default value if this object does not contain a member with that name

getDouble

public double getDouble(java.lang.String name,
                        double defaultValue)

Returns the double value of the member with the specified name in this object. If this object does not contain a member with this name, the given default value is returned. If this object contains multiple members with the given name, the last one will be picked. If this member's value does not represent a JSON number or if it cannot be interpreted as Java double, an exception is thrown.

Parameters:

name - the name of the member whose value is to be returned

defaultValue - the value to be returned if the requested member is missing

Returns:

the value of the last member with the specified name, or the given default value if this object does not contain a member with that name

getBoolean

public boolean getBoolean(java.lang.String name,
                          boolean defaultValue)

Returns the boolean value of the member with the specified name in this object. If this object does not contain a member with this name, the given default value is returned. If this object contains multiple members with the given name, the last one will be picked. If this member's value does not represent a JSON true or false value, an exception is thrown.

Parameters:

name - the name of the member whose value is to be returned

defaultValue - the value to be returned if the requested member is missing

Returns:

the value of the last member with the specified name, or the given default value if this object does not contain a member with that name

getString

public java.lang.String getString(java.lang.String name,
                                  java.lang.String defaultValue)

Returns the String value of the member with the specified name in this object. If this object does not contain a member with this name, the given default value is returned. If this object contains multiple members with the given name, the last one is picked. If this member's value does not represent a JSON string, an exception is thrown.

Parameters:

name - the name of the member whose value is to be returned

defaultValue - the value to be returned if the requested member is missing

Returns:

the value of the last member with the specified name, or the given default value if this object does not contain a member with that name

size

public int size()

Returns the number of members (name/value pairs) in this object.

Returns:

the number of members in this object

isEmpty

public boolean isEmpty()

Returns true if this object contains no members.

Returns:

true if this object contains no members

names

public java.util.List<java.lang.String> names()

Returns a list of the names in this object in document order. The returned list is backed by this object and will reflect subsequent changes. It cannot be used to modify this object. Attempts to modify the returned list will result in an exception.

Returns:

a list of the names in this object

iterator

public java.util.Iterator<JsonObject.Member> iterator()

Returns an iterator over the members of this object in document order. The returned iterator cannot be used to modify this object.

Specified by:

iterator in interface java.lang.Iterable<JsonObject.Member>

Returns:

an iterator over the members of this object

isObject

public boolean isObject()

Description copied from class: JsonValue

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

Overrides:

isObject in class JsonValue

Returns:

true if this value is an instance of JsonObject

asObject

public JsonObject asObject()

Description copied from class: JsonValue

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

Overrides:

asObject in class JsonValue

Returns:

a JSONObject for this value

hashCode

public int hashCode()

Overrides:

hashCode in class JsonValue

equals

public boolean equals(java.lang.Object obj)

Description copied from class: JsonValue

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 JsonValue

Parameters:

obj - the reference object with which to compare

Returns:

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