Package net.sourceforge.plantuml.json

Class JsonObject

java.lang.Object
net.sourceforge.plantuml.json.JsonValue
net.sourceforge.plantuml.json.JsonObject
All Implemented Interfaces:
Serializable, Iterable<JsonObject.Member>
public class JsonObject extends JsonValue implements 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:

  • Constructor Details

    • 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 Details

    • cloneMe

      public JsonValue cloneMe()
      Added for PlantUML
      Overrides:
      cloneMe in class JsonValue

    • readFrom

      @Deprecated public static JsonObject readFrom(Reader reader) throws 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:
      IOException - if an I/O error occurs in the reader
      ParseException - if the input is not valid JSON
      UnsupportedOperationException - if the input does not contain a JSON object

    • readFrom

      @Deprecated public static JsonObject readFrom(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
      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(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(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(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(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(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(String name, 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(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(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(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(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(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(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(String name, 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(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(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(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 deep merge
      Returns:
      the object itself, to enable method chaining

    • get

      public JsonValue get(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

    • getInt

      public int getInt(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(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(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(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(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 String getString(String name, 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 List<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 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 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(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