JsonObject.java
/*
* Copyright (C) 2008 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.gson;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.gson.internal.LinkedTreeMap;
import java.util.Map;
import java.util.Set;
/**
* A class representing an object type in JSON. An object consists of name-value pairs where names
* are strings, and values are any other type of {@link JsonElement}. This allows for a creating a
* tree of JsonElements. The member elements of this object are maintained in order they were added.
* This class does not support {@code null} values. If {@code null} is provided as value argument to
* any of the methods, it is converted to a {@link JsonNull}.
*
* <p>{@code JsonObject} does not implement the {@link Map} interface, but a {@code Map} view of it
* can be obtained with {@link #asMap()}.
*
* <p>See the {@link JsonElement} documentation for details on how to convert {@code JsonObject} and
* generally any {@code JsonElement} from and to JSON.
*
* @author Inderjeet Singh
* @author Joel Leitch
*/
public final class JsonObject extends JsonElement {
private final LinkedTreeMap<String, JsonElement> members = new LinkedTreeMap<>(false);
/** Creates an empty JsonObject. */
@SuppressWarnings("deprecation") // superclass constructor
public JsonObject() {}
/**
* Creates a deep copy of this element and all its children.
*
* @since 2.8.2
*/
@Override
public JsonObject deepCopy() {
JsonObject result = new JsonObject();
for (Map.Entry<String, JsonElement> entry : members.entrySet()) {
result.add(entry.getKey(), entry.getValue().deepCopy());
}
return result;
}
/**
* Adds a member, which is a name-value pair, to self. The name must be a String, but the value
* can be an arbitrary {@link JsonElement}, thereby allowing you to build a full tree of
* JsonElements rooted at this node.
*
* @param property name of the member.
* @param value the member object.
*/
public void add(String property, JsonElement value) {
members.put(property, value == null ? JsonNull.INSTANCE : value);
}
/**
* Removes the {@code property} from this object.
*
* @param property name of the member that should be removed.
* @return the {@link JsonElement} object that is being removed, or {@code null} if no member with
* this name exists.
* @since 1.3
*/
@CanIgnoreReturnValue
public JsonElement remove(String property) {
return members.remove(property);
}
/**
* Convenience method to add a string member. The specified value is converted to a {@link
* JsonPrimitive} of String.
*
* @param property name of the member.
* @param value the string value associated with the member.
*/
public void addProperty(String property, String value) {
add(property, value == null ? JsonNull.INSTANCE : new JsonPrimitive(value));
}
/**
* Convenience method to add a number member. The specified value is converted to a {@link
* JsonPrimitive} of Number.
*
* @param property name of the member.
* @param value the number value associated with the member.
*/
public void addProperty(String property, Number value) {
add(property, value == null ? JsonNull.INSTANCE : new JsonPrimitive(value));
}
/**
* Convenience method to add a boolean member. The specified value is converted to a {@link
* JsonPrimitive} of Boolean.
*
* @param property name of the member.
* @param value the boolean value associated with the member.
*/
public void addProperty(String property, Boolean value) {
add(property, value == null ? JsonNull.INSTANCE : new JsonPrimitive(value));
}
/**
* Convenience method to add a char member. The specified value is converted to a {@link
* JsonPrimitive} of Character.
*
* @param property name of the member.
* @param value the char value associated with the member.
*/
public void addProperty(String property, Character value) {
add(property, value == null ? JsonNull.INSTANCE : new JsonPrimitive(value));
}
/**
* Returns a set of members of this object. The set is ordered, and the order is in which the
* elements were added.
*
* @return a set of members of this object.
*/
public Set<Map.Entry<String, JsonElement>> entrySet() {
return members.entrySet();
}
/**
* Returns a set of members key values.
*
* @return a set of member keys as Strings
* @since 2.8.1
*/
public Set<String> keySet() {
return members.keySet();
}
/**
* Returns the number of key/value pairs in the object.
*
* @return the number of key/value pairs in the object.
* @since 2.7
*/
public int size() {
return members.size();
}
/**
* Returns true if the number of key/value pairs in the object is zero.
*
* @return true if the number of key/value pairs in the object is zero.
* @since 2.10.1
*/
public boolean isEmpty() {
return members.size() == 0;
}
/**
* Convenience method to check if a member with the specified name is present in this object.
*
* @param memberName name of the member that is being checked for presence.
* @return true if there is a member with the specified name, false otherwise.
*/
public boolean has(String memberName) {
return members.containsKey(memberName);
}
/**
* Returns the member with the specified name.
*
* @param memberName name of the member that is being requested.
* @return the member matching the name, or {@code null} if no such member exists.
*/
public JsonElement get(String memberName) {
return members.get(memberName);
}
/**
* Convenience method to get the specified member as a {@link JsonPrimitive}.
*
* @param memberName name of the member being requested.
* @return the {@code JsonPrimitive} corresponding to the specified member, or {@code null} if no
* member with this name exists.
* @throws ClassCastException if the member is not of type {@code JsonPrimitive}.
*/
public JsonPrimitive getAsJsonPrimitive(String memberName) {
return (JsonPrimitive) members.get(memberName);
}
/**
* Convenience method to get the specified member as a {@link JsonArray}.
*
* @param memberName name of the member being requested.
* @return the {@code JsonArray} corresponding to the specified member, or {@code null} if no
* member with this name exists.
* @throws ClassCastException if the member is not of type {@code JsonArray}.
*/
public JsonArray getAsJsonArray(String memberName) {
return (JsonArray) members.get(memberName);
}
/**
* Convenience method to get the specified member as a {@link JsonObject}.
*
* @param memberName name of the member being requested.
* @return the {@code JsonObject} corresponding to the specified member, or {@code null} if no
* member with this name exists.
* @throws ClassCastException if the member is not of type {@code JsonObject}.
*/
public JsonObject getAsJsonObject(String memberName) {
return (JsonObject) members.get(memberName);
}
/**
* Returns a mutable {@link Map} view of this {@code JsonObject}. Changes to the {@code Map} are
* visible in this {@code JsonObject} and the other way around.
*
* <p>The {@code Map} does not permit {@code null} keys or values. Unlike {@code JsonObject}'s
* {@code null} handling, a {@link NullPointerException} is thrown when trying to add {@code
* null}. Use {@link JsonNull} for JSON null values.
*
* @return mutable {@code Map} view
* @since 2.10
*/
public Map<String, JsonElement> asMap() {
// It is safe to expose the underlying map because it disallows null keys and values
return members;
}
/**
* Returns whether the other object is equal to this. This method only considers the other object
* to be equal if it is an instance of {@code JsonObject} and has equal members, ignoring order.
*/
@Override
public boolean equals(Object o) {
return (o == this) || (o instanceof JsonObject && ((JsonObject) o).members.equals(members));
}
/**
* Returns the hash code of this object. This method calculates the hash code based on the members
* of this object, ignoring order.
*/
@Override
public int hashCode() {
return members.hashCode();
}
}