/*
* 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 java.io.IOException;
import java.util.LinkedHashMap;
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.
*
* @author Inderjeet Singh
* @author Joel Leitch
*/
public final class JsonObject extends JsonElement {
// We are using a linked hash map because it is important to preserve
// the order in which elements are inserted. This is needed to ensure
// that the fields of an object are inserted in the order they were
// defined in the class.
private final Map<String, JsonElement> members;
/**
* Creates an empty JsonObject.
*/
public JsonObject() {
members = new LinkedHashMap<String, JsonElement>();
}
/**
* Adds a member, which is a name-value pair, to self. The name must be a
* String, but the value can be an arbitrary 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) {
Preconditions.checkArgument(property != null
&& !"".equals(property.trim()));
if (value == null) {
value = JsonNull.createJsonNull();
}
members.put(property, value);
}
/**
* Removes the {@code property} from this {@link JsonObject}.
*
* @param property
* name of the member that should be removed.
* @return the {@link JsonElement} object that is being removed.
* @since 1.3
*/
public JsonElement remove(String property) {
return members.remove(property);
}
/**
* Convenience method to add a primitive member. The specified value is
* converted to a 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, createJsonElement(value));
}
/**
* Convenience method to add a primitive member. The specified value is
* converted to a 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, createJsonElement(value));
}
/**
* Convenience method to add a boolean member. The specified value is
* converted to a JsonPrimitive of Boolean.
*
* @param property
* name of the member.
* @param value
* the number value associated with the member.
*/
public void addProperty(String property, Boolean value) {
add(property, createJsonElement(value));
}
/**
* Convenience method to add a char member. The specified value is converted
* to a JsonPrimitive of Character.
*
* @param property
* name of the member.
* @param value
* the number value associated with the member.
*/
public void addProperty(String property, Character value) {
add(property, createJsonElement(value));
}
/**
* Creates the proper {@link JsonElement} object from the given {@code
* value} object.
*
* @param value
* the object to generate the {@link JsonElement} for
* @return a {@link JsonPrimitive} if the {@code value} is not null,
* otherwise a {@link JsonNull}
*/
private JsonElement createJsonElement(Object value) {
if (value == null) {
return JsonNull.createJsonNull();
} else {
return 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();
}
/**
* 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. Null if no such member exists.
*/
public JsonElement get(String memberName) {
if (members.containsKey(memberName)) {
JsonElement member = members.get(memberName);
return member == null ? JsonNull.createJsonNull() : member;
} else {
return null;
}
}
public String getAsString(String memberName){
return get(memberName).getAsString();
}
/**
* Convenience method to get the specified member as a JsonPrimitive
* element.
*
* @param memberName
* name of the member being requested.
* @return the JsonPrimitive corresponding to the specified member.
*/
public JsonPrimitive getAsJsonPrimitive(String memberName) {
return (JsonPrimitive) members.get(memberName);
}
/**
* Convenience method to get the specified member as a JsonArray.
*
* @param memberName
* name of the member being requested.
* @return the JsonArray corresponding to the specified member.
*/
public JsonArray getAsJsonArray(String memberName) {
return (JsonArray) members.get(memberName);
}
/**
* Convenience method to get the specified member as a JsonObject.
*
* @param memberName
* name of the member being requested.
* @return the JsonObject corresponding to the specified member.
*/
public JsonObject getAsJsonObject(String memberName) {
return (JsonObject) members.get(memberName);
}
@Override
protected void toString(Appendable sb, Escaper escaper) throws IOException {
sb.append('{');
boolean first = true;
for (Map.Entry<String, JsonElement> entry : members.entrySet()) {
if (first) {
first = false;
} else {
sb.append(',');
}
sb.append('\"');
sb.append(entry.getKey());
sb.append("\":");
entry.getValue().toString(sb, escaper);
}
sb.append('}');
}
}
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