jakarta.json.JsonArray Maven / Gradle / Ivy
/*
* Copyright (c) 2011, 2020 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0, which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception, which is available at
* https://www.gnu.org/software/classpath/license.html.
*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
package jakarta.json;
import java.util.List;
import java.util.function.Function;
import java.util.stream.Collectors;
import java.util.stream.Stream;
/**
* {@code JsonArray} represents an immutable JSON array
* (an ordered sequence of zero or more values).
* It also provides an unmodifiable list view of the values in the array.
*
* A {@code JsonArray} object can be created by reading JSON data from
* an input source or it can be built from scratch using an array builder
* object.
*
*
The following example demonstrates how to create a {@code JsonArray}
* object from an input source using the method {@link JsonReader#readArray()}:
*
* JsonReader jsonReader = Json.createReader(...);
* JsonArray array = jsonReader.readArray();
* jsonReader.close();
*
*
* The following example demonstrates how to build an empty JSON array
* using the class {@link JsonArrayBuilder}:
*
* JsonArray array = Json.createArrayBuilder().build();
*
*
* The example code below demonstrates how to create the following JSON array:
*
* [
* { "type": "home", "number": "212 555-1234" },
* { "type": "fax", "number": "646 555-4567" }
* ]
*
*
* JsonArray value = Json.createArrayBuilder()
* .add(Json.createObjectBuilder()
* .add("type", "home")
* .add("number", "212 555-1234"))
* .add(Json.createObjectBuilder()
* .add("type", "fax")
* .add("number", "646 555-4567"))
* .build();
*
*
* The following example demonstrates how to write a {@code JsonArray} object
* as JSON data:
*
* JsonArray arr = ...;
* JsonWriter writer = Json.createWriter(...)
* writer.writeArray(arr);
* writer.close();
*
*
* The values in a {@code JsonArray} can be of the following types:
* {@link JsonObject}, {@link JsonArray},
* {@link JsonString}, {@link JsonNumber}, {@link JsonValue#TRUE},
* {@link JsonValue#FALSE}, and {@link JsonValue#NULL}.
* {@code JsonArray} provides various accessor methods to access the values
* in an array.
*
*
The following example shows how to obtain the home phone number
* "212 555-1234" from the array built in the previous example:
*
* JsonObject home = array.getJsonObject(0);
* String number = home.getString("number");
*
*
* {@code JsonArray} instances are list objects that provide read-only
* access to the values in the JSON array. Any attempt to modify the list,
* whether directly or using its collection views, results in an
* {@code UnsupportedOperationException}.
*/
public interface JsonArray extends JsonStructure, List {
/**
* Returns the object value at the specified position in this array.
* This is a convenience method for {@code (JsonObject)get(index)}.
*
* @param index index of the value to be returned
* @return the value at the specified position in this array
* @throws IndexOutOfBoundsException if the index is out of range
* @throws ClassCastException if the value at the specified position is not
* assignable to the JsonObject type
*/
JsonObject getJsonObject(int index);
/**
* Returns the array value at the specified position in this array.
* This is a convenience method for {@code (JsonArray)get(index)}.
*
* @param index index of the value to be returned
* @return the value at the specified position in this array
* @throws IndexOutOfBoundsException if the index is out of range
* @throws ClassCastException if the value at the specified position is not
* assignable to the JsonArray type
*/
JsonArray getJsonArray(int index);
/**
* Returns the number value at the specified position in this array.
* This is a convenience method for {@code (JsonNumber)get(index)}.
*
* @param index index of the value to be returned
* @return the value at the specified position in this array
* @throws IndexOutOfBoundsException if the index is out of range
* @throws ClassCastException if the value at the specified position is not
* assignable to the JsonNumber type
*/
JsonNumber getJsonNumber(int index);
/**
* Returns the string value at ths specified position in this array.
* This is a convenience method for {@code (JsonString)get(index)}.
*
* @param index index of the value to be returned
* @return the value at the specified position in this array
* @throws IndexOutOfBoundsException if the index is out of range
* @throws ClassCastException if the value at the specified position is not
* assignable to the JsonString type
*/
JsonString getJsonString(int index);
/**
* Returns a list view of the specified type for the array. This method
* does not verify if there is a value of wrong type in the array. Providing
* this typesafe view dynamically may cause a program fail with a
* {@code ClassCastException}, if there is a value of wrong type in this
* array. Unfortunately, the exception can occur at any time after this
* method returns.
*
* @param The type of the List for the array
* @param clazz a JsonValue type
* @return a list view of the specified type
*/
List getValuesAs(Class clazz);
/**
* Returns a list view for the array. The value and the type of the elements
* in the list is specified by the {@code func} argument.
* This method can be used to obtain a list of the unwrapped types, such as
*
{@code
* List strings = ary1.getValuesAs(JsonString::getString);
* List ints = ary2.getValuesAs(JsonNumber::intValue);
* }
* or a list of simple projections, such as
* {@code
* List stringsizes = ary1.getValueAs((JsonString v)->v.getString().length();
* }
* @param The element type (must be a subtype of JsonValue) of this JsonArray.
* @param The element type of the returned List
* @param func The function that maps the elements of this JsonArray to the target elements.
* @return A List of the specified values and type.
* @throws ClassCastException if the {@code JsonArray} contains a value of wrong type
*
* @since 1.1
*/
default List getValuesAs(Function func) {
@SuppressWarnings("unchecked")
Stream stream = (Stream) stream();
return stream.map(func).collect(Collectors.toList());
}
/**
* A convenience method for
* {@code getJsonString(index).getString()}.
*
* @param index index of the {@code JsonString} value
* @return the String value at the specified position
* @throws IndexOutOfBoundsException if the index is out of range
* @throws ClassCastException if the value at the specified position is not
* assignable to {@code JsonString}
*/
String getString(int index);
/**
* Returns the {@code String} value of {@code JsonString} at the specified
* position in this JSON array values. If {@code JsonString} is found,
* its {@link jakarta.json.JsonString#getString()} is returned. Otherwise,
* the specified default value is returned.
*
* @param index index of the {@code JsonString} value
* @param defaultValue the String to return if the {@code JsonValue} at the
* specified position is not a {@code JsonString}
* @return the String value at the specified position in this array,
* or the specified default value
*/
String getString(int index, String defaultValue);
/**
* A convenience method for
* {@code getJsonNumber(index).intValue()}.
*
* @param index index of the {@code JsonNumber} value
* @return the int value at the specified position
* @throws IndexOutOfBoundsException if the index is out of range
* @throws ClassCastException if the value at the specified position is not
* assignable to {@code JsonNumber}
*/
int getInt(int index);
/**
* Returns the int value of the {@code JsonNumber} at the specified position.
* If the value at that position is a {@code JsonNumber},
* this method returns {@link jakarta.json.JsonNumber#intValue()}. Otherwise
* this method returns the specified default value.
*
* @param index index of the {@code JsonNumber} value
* @param defaultValue the int value to return if the {@code JsonValue} at
* the specified position is not a {@code JsonNumber}
* @return the int value at the specified position in this array,
* or the specified default value
*/
int getInt(int index, int defaultValue);
/**
* Returns the boolean value at the specified position.
* If the value at the specified position is {@code JsonValue.TRUE}
* this method returns {@code true}. If the value at the specified position
* is {@code JsonValue.FALSE} this method returns {@code false}.
*
* @param index index of the JSON boolean value
* @return the boolean value at the specified position
* @throws IndexOutOfBoundsException if the index is out of range
* @throws ClassCastException if the value at the specified position is not
* assignable to {@code JsonValue.TRUE} or {@code JsonValue.FALSE}
*/
boolean getBoolean(int index);
/**
* Returns the boolean value at the specified position.
* If the value at the specified position is {@code JsonValue.TRUE}
* this method returns {@code true}. If the value at the specified position
* is {@code JsonValue.FALSE} this method returns {@code false}.
* Otherwise this method returns the specified default value.
*
* @param index index of the JSON boolean value
* @param defaultValue the boolean value to return if the {@code JsonValue}
* at the specified position is neither TRUE nor FALSE
* @return the boolean value at the specified position,
* or the specified default value
*/
boolean getBoolean(int index, boolean defaultValue);
/**
* Returns {@code true} if the value at the specified location in this
* array is {@code JsonValue.NULL}.
*
* @param index index of the JSON null value
* @return return true if the value at the specified location is
* {@code JsonValue.NULL}, otherwise false
* @throws IndexOutOfBoundsException if the index is out of range
*/
boolean isNull(int index);
}