org.apache.juneau

Class ObjectList

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractList<E>

java.util.AbstractSequentialList<E>

java.util.LinkedList<Object>

org.apache.juneau.ObjectList

All Implemented Interfaces:

Serializable, Cloneable, Iterable<Object>, Collection<Object>, Deque<Object>, List<Object>, Queue<Object>

Direct Known Subclasses:

DelegateList

public class ObjectList
extends LinkedList<Object>

Java implementation of a JSON array.

An extension of LinkedList, so all methods available to in that class are also available to this class.

Note that the use of this class is optional. The serializers will accept any objects that implement the Collection interface. But this class provides some useful additional functionality when working with JSON models constructed from Java Collections Framework objects. For example, a constructor is provided for converting a JSON array string directly into a List. It also contains accessor methods for to avoid common typecasting when accessing elements in a list.

Example:

// Construct an empty List List l = new ObjectList(); // Construct a list of objects using various methods l = new ObjectList().append("foo").append(123).append(true); l = new ObjectList().append("foo", 123, true); // Equivalent l = new ObjectList("foo", 123, true); // Equivalent // Construct a list of integers from JSON l = new ObjectList("[1,2,3]"); // Construct a list of generic ObjectMap objects from JSON l = new ObjectList("[{foo:'bar'},{baz:'bing'}]"); // Construct a list of integers from XML String xml = "<array><number>1</number><number>2</number><number>3</number></array>"; l = new ObjectList(xml, DataFormat.XML); l = (List)XmlParser.DEFAULT.parse(xml); // Equivalent l = (List)XmlParser.DEFAULT.parse(Object.class, xml); // Equivalent l = XmlParser.DEFAULT.parse(List.class, xml); // Equivalent l = XmlParser.DEFAULT.parse(ObjectList.class, xml); // Equivalent // Construct JSON from ObjectList l = new ObjectList("[{foo:'bar'},{baz:'bing'}]"); String json = l.toString(); // Produces "[{foo:'bar'},{baz:'bing'}]" json = l.toString(JsonSerializer.DEFAULT_CONDENSED); // Equivalent json = JsonSerializer.DEFAULT_CONDENSED.serialize(l); // Equivalent // Get one of the entries in the list as an Integer l = new ObjectList("[1,2,3]"); Integer i = l.getInt(1); i = l.get(Integer.class, 1); // Equivalent // Get one of the entries in the list as an Float l = new ObjectList("[1,2,3]"); Float f = l.getFloat(1); // Returns 2f f = l.get(Float.class, 1); // Equivalent // Same as above, except converted to a String l = new ObjectList("[1,2,3]"); String s = l.getString(1); // Returns "2" s = l.get(String.class, 1); // Equivalent // Get one of the entries in the list as a bean (converted to a bean if it isn't already one) l = new ObjectList("[{name:'John Smith',age:45}]"); Person p = l.get(Person.class, 0); // Iterate over a list of beans using the elements() method ObjectList ObjectList = new ObjectList("[{name:'John Smith',age:45}]"); for (Person p : ObjectList.elements(Person.class) { // Do something with p }

This class is not thread safe.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static ObjectList	EMPTY_LIST An empty read-only ObjectList.

Fields inherited from class java.util.AbstractList

modCount

Constructor Summary

Constructors

Constructor and Description
ObjectList() Construct an empty JSON array.
ObjectList(BeanSession session) Construct an empty JSON array with the specified bean context.
ObjectList(CharSequence s) Shortcut for new ObjectList(String,JsonParser.DEFAULT);
ObjectList(CharSequence s, Parser p) Construct a JSON array directly from text using the specified parser.
ObjectList(Collection<?> c) Construct a JSON array and fill it with the specified collection of objects.
ObjectList(Object... o) Construct a JSON array and fill it with the specified objects.
ObjectList(Reader r) Shortcut for new ObjectList(reader, JsonParser.DEFAULT).
ObjectList(Reader r, Parser p) Construct a JSON array directly from a reader using the specified parser.

Method Summary

Modifier and Type	Method and Description
ObjectList	append(Object... o) Convenience method for adding multiple objects to this list.
Object	deleteAt(String path) Similar to remove(int),but the key is a slash-delimited path used to traverse entries in this POJO.
<E> Iterable<E>	elements(Class<E> childType) Creates an Iterable with elements of the specified child type.
<T> T	get(int index, Class<T> type) Get the entry at the specified index, converted to the specified type.
<T> T	get(int index, Type type, Type... args) Get the entry at the specified index, converted to the specified type.
<T> T	getAt(String path, Class<T> type) Same as get(int,Class), but the key is a slash-delimited path used to traverse entries in this POJO.
<T> T	getAt(String path, Type type, Type... args) Same as getAt(String,Class), but allows for conversion to complex maps and collections.
Boolean	getBoolean(int index) Shortcut for calling get(index, Boolean.class).
ClassMeta<?>	getClassMeta(int index) Returns the ClassMeta of the class of the object at the specified index.
Integer	getInt(int index) Shortcut for calling get(index, Integer.class).
List<?>	getList(int index) Shortcut for calling get(index, List.class).
<E> List<E>	getList(int index, Class<E> elementType) Same as getList(int) except converts the elements to the specified types.
Long	getLong(int index) Shortcut for calling get(index, Long.class).
Map<?,?>	getMap(int index) Shortcut for calling get(index, Map.class).
<K,V> Map<K,V>	getMap(int index, Class<K> keyType, Class<V> valType) Same as getMap(int) except converts the keys and values to the specified types.
ObjectList	getObjectList(int index) Shortcut for calling get(index, ObjectList.class).
ObjectMap	getObjectMap(int index) Shortcut for calling get(index, ObjectMap.class).
String	getString(int index) Shortcut for calling get(index, String.class).
Object	postAt(String path, Object o) Similar to putAt(String,Object), but used to append to collections and arrays.
Object	putAt(String path, Object o) Same as set(int,Object), but the key is a slash-delimited path used to traverse entries in this POJO.
void	serializeTo(Writer w) Convenience method for serializing this ObjectList to the specified Writer using the JsonSerializer.DEFAULT serializer.
ObjectList	setBeanSession(BeanSession session) Override the default bean session used for converting POJOs.
String	toString() Serialize this array to JSON using the JsonSerializer.DEFAULT serializer.
String	toString(WriterSerializer serializer) Serialize this array to a string using the specified serializer.

Methods inherited from class java.util.LinkedList

add, add, addAll, addAll, addFirst, addLast, clear, clone, contains, descendingIterator, element, get, getFirst, getLast, indexOf, lastIndexOf, listIterator, offer, offerFirst, offerLast, peek, peekFirst, peekLast, poll, pollFirst, pollLast, pop, push, remove, remove, remove, removeFirst, removeFirstOccurrence, removeLast, removeLastOccurrence, set, size, spliterator, toArray, toArray

Methods inherited from class java.util.AbstractSequentialList

iterator

Methods inherited from class java.util.AbstractList

equals, hashCode, listIterator, removeRange, subList

Methods inherited from class java.util.AbstractCollection

containsAll, isEmpty, removeAll, retainAll

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.List

containsAll, equals, hashCode, isEmpty, iterator, listIterator, removeAll, replaceAll, retainAll, sort, subList

Methods inherited from interface java.util.Deque

iterator

Methods inherited from interface java.util.Collection

parallelStream, removeIf, stream

Methods inherited from interface java.lang.Iterable

forEach

Field Detail

EMPTY_LIST

public static final ObjectList EMPTY_LIST

An empty read-only ObjectList.

Constructor Detail

ObjectList

public ObjectList(CharSequence s,
                  Parser p)
           throws ParseException

Construct a JSON array directly from text using the specified parser.

Parameters:

s - The string being parsed.

p - The parser to use to parse the input.

Throws:

ParseException - If the input contains a syntax error or is malformed.

ObjectList

public ObjectList(CharSequence s)
           throws ParseException

Shortcut for new ObjectList(String,JsonParser.DEFAULT);

Parameters:

s - The string being parsed.

Throws:

ParseException - If the input contains a syntax error or is malformed.

ObjectList

public ObjectList(Reader r,
                  Parser p)
           throws ParseException,
                  IOException

Construct a JSON array directly from a reader using the specified parser.

Parameters:

r - The reader to read from. Will automatically be wrapped in a BufferedReader if it isn't already a BufferedReader.

p - The parser to use to parse the input.

Throws:

ParseException - If the input contains a syntax error or is malformed.

IOException - If a problem occurred trying to read from the reader.

ObjectList

public ObjectList(Reader r)
           throws ParseException,
                  IOException

Shortcut for new ObjectList(reader, JsonParser.DEFAULT).

Parameters:

r - The reader to read from. The reader will be wrapped in a BufferedReader if it isn't already.

Throws:

ParseException - If the input contains a syntax error or is malformed.

IOException - If a problem occurred trying to read from the reader.

ObjectList

public ObjectList()

Construct an empty JSON array. (i.e. an empty LinkedList).

ObjectList

public ObjectList(BeanSession session)

Construct an empty JSON array with the specified bean context. (i.e. an empty LinkedList).

Parameters:

session - The bean context to associate with this object list for creating beans.

ObjectList

public ObjectList(Object... o)

Construct a JSON array and fill it with the specified objects.

Parameters:

o - A list of objects to add to this list.

ObjectList

public ObjectList(Collection<?> c)

Construct a JSON array and fill it with the specified collection of objects.

Parameters:

c - A list of objects to add to this list.

Method Detail

setBeanSession

public ObjectList setBeanSession(BeanSession session)

Override the default bean session used for converting POJOs.

Default is BeanContext.DEFAULT, which is sufficient in most cases.

Useful if you're serializing/parsing beans with transforms defined.

Parameters:

session - The new bean session.

Returns:

This object (for method chaining).

append

public ObjectList append(Object... o)

Convenience method for adding multiple objects to this list.

Parameters:

o - The objects to add to the list.

Returns:

This object (for method chaining).

get

public <T> T get(int index,
                 Class<T> type)

Get the entry at the specified index, converted to the specified type.

This is the preferred get method for simple types.

Examples:

ObjectList l = new ObjectList("..."); // Value converted to a string. String s = l.get(1, String.class); // Value converted to a bean. MyBean b = l.get(2, MyBean.class); // Value converted to a bean array. MyBean[] ba = l.get(3, MyBean[].class); // Value converted to a linked-list of objects. List l1 = l.get(4, LinkedList.class); // Value converted to a map of object keys/values. Map m1 = l.get(5, TreeMap.class);

See BeanSession.convertToType(Object, ClassMeta) for the list of valid data conversions.

Type Parameters:

T - The type of object to convert the entry to.

Parameters:

index - The index into this list.

type - The type of object to convert the entry to.

Returns:

The converted entry.

get

public <T> T get(int index,
                 Type type,
                 Type... args)

Get the entry at the specified index, converted to the specified type.

The type can be a simple type (e.g. beans, strings, numbers) or parameterized type (collections/maps).

Examples:

ObjectList l = new ObjectList("..."); // Value converted to a linked-list of strings. List<String> l1 = l.get(1, LinkedList.class, String.class); // Value converted to a linked-list of beans. List<MyBean> l2 = l.get(2, LinkedList.class, MyBean.class); // Value converted to a linked-list of linked-lists of strings. List<List<String>> l3 = l.get(3, LinkedList.class, LinkedList.class, String.class); // Value converted to a map of string keys/values. Map<String,String> m1 = l.get(4, TreeMap.class, String.class, String.class); // Value converted to a map containing string keys and values of lists containing beans. Map<String,List<MyBean>> m2 = l.get(5, TreeMap.class, String.class, List.class, MyBean.class);

Collection classes are assumed to be followed by zero or one objects indicating the element type.

Map classes are assumed to be followed by zero or two meta objects indicating the key and value types.

The array can be arbitrarily long to indicate arbitrarily complex data structures.

See BeanSession.convertToType(Object, ClassMeta) for the list of valid data conversions.

Type Parameters:

T - The type of object to convert the entry to.

Parameters:

index - The index into this list.

type - The type of object to convert the entry to.

args - The type arguments of the type to convert the entry to.

Returns:

The converted entry.

getString

public String getString(int index)

Shortcut for calling get(index, String.class).

Parameters:

index - The index.

Returns:

The converted value.

getInt

public Integer getInt(int index)

Shortcut for calling get(index, Integer.class).

Parameters:

index - The index.

Returns:

The converted value.

Throws:

InvalidDataConversionException - If value cannot be converted.

getBoolean

public Boolean getBoolean(int index)

Shortcut for calling get(index, Boolean.class).

Parameters:

index - The index.

Returns:

The converted value.

Throws:

InvalidDataConversionException - If value cannot be converted.

getLong

public Long getLong(int index)

Shortcut for calling get(index, Long.class).

Parameters:

index - The index.

Returns:

The converted value.

Throws:

InvalidDataConversionException - If value cannot be converted.

getMap

public Map<?,?> getMap(int index)

Shortcut for calling get(index, Map.class).

Parameters:

index - The index.

Returns:

The converted value.

Throws:

InvalidDataConversionException - If value cannot be converted.

getMap

public <K,V> Map<K,V> getMap(int index,
                             Class<K> keyType,
                             Class<V> valType)

Same as getMap(int) except converts the keys and values to the specified types.

Parameters:

index - The index.

keyType - The key type class.

valType - The value type class.

Returns:

The converted value.

Throws:

InvalidDataConversionException - If value cannot be converted.

getList

public List<?> getList(int index)

Shortcut for calling get(index, List.class).

Parameters:

index - The index.

Returns:

The converted value.

Throws:

InvalidDataConversionException - If value cannot be converted.

getList

public <E> List<E> getList(int index,
                           Class<E> elementType)

Same as getList(int) except converts the elements to the specified types.

Parameters:

index - The index.

elementType - The element type class.

Returns:

The converted value.

Throws:

InvalidDataConversionException - If value cannot be converted.

getObjectMap

public ObjectMap getObjectMap(int index)

Shortcut for calling get(index, ObjectMap.class).

Parameters:

index - The index.

Returns:

The converted value.

Throws:

InvalidDataConversionException - If value cannot be converted.

getObjectList

public ObjectList getObjectList(int index)

Shortcut for calling get(index, ObjectList.class).

Parameters:

index - The index.

Returns:

The converted value.

Throws:

InvalidDataConversionException - If value cannot be converted.

getAt

public <T> T getAt(String path,
                   Class<T> type)

Same as get(int,Class), but the key is a slash-delimited path used to traverse entries in this POJO.

For example, the following code is equivalent:

ObjectMap m = getObjectMap(); // Long way long l = m.getObjectMap("foo").getObjectList("bar").getObjectMap("0").getLong("baz"); // Using this method long l = m.getAt("foo/bar/0/baz", long.class);

This method uses the PojoRest class to perform the lookup, so the map can contain any of the various class types that the PojoRest class supports (e.g. beans, collections, arrays).

Type Parameters:

T - The class type.

Parameters:

path - The path to the entry.

type - The class type.

Returns:

The value, or null if the entry doesn't exist.

getAt

public <T> T getAt(String path,
                   Type type,
                   Type... args)

Same as getAt(String,Class), but allows for conversion to complex maps and collections.

Type Parameters:

T - The class type.

Parameters:

path - The path to the entry.

type - The class type.

args - The class parameter types.

Returns:

The value, or null if the entry doesn't exist.

putAt

public Object putAt(String path,
                    Object o)

Same as set(int,Object), but the key is a slash-delimited path used to traverse entries in this POJO.

For example, the following code is equivalent:

ObjectMap m = getObjectMap(); // Long way m.getObjectMap("foo").getObjectList("bar").getObjectMap("0").put("baz", 123); // Using this method m.putAt("foo/bar/0/baz", 123);

This method uses the PojoRest class to perform the lookup, so the map can contain any of the various class types that the PojoRest class supports (e.g. beans, collections, arrays).

Parameters:

path - The path to the entry.

o - The new value.

Returns:

The previous value, or null if the entry doesn't exist.

postAt

public Object postAt(String path,
                     Object o)

Similar to putAt(String,Object), but used to append to collections and arrays.

For example, the following code is equivalent:

ObjectMap m = getObjectMap(); // Long way m.getObjectMap("foo").getObjectList("bar").append(123); // Using this method m.postAt("foo/bar", 123);

This method uses the PojoRest class to perform the lookup, so the map can contain any of the various class types that the PojoRest class supports (e.g. beans, collections, arrays).

Parameters:

path - The path to the entry.

o - The new value.

Returns:

The previous value, or null if the entry doesn't exist.

deleteAt

public Object deleteAt(String path)

Similar to remove(int),but the key is a slash-delimited path used to traverse entries in this POJO.

For example, the following code is equivalent:

ObjectMap m = getObjectMap(); // Long way m.getObjectMap("foo").getObjectList("bar").getObjectMap(1).remove("baz"); // Using this method m.deleteAt("foo/bar/0/baz");

This method uses the PojoRest class to perform the lookup, so the map can contain any of the various class types that the PojoRest class supports (e.g. beans, collections, arrays).

Parameters:

path - The path to the entry.

Returns:

The previous value, or null if the entry doesn't exist.

elements

public <E> Iterable<E> elements(Class<E> childType)

Creates an Iterable with elements of the specified child type.

Attempts to convert the child objects to the correct type if they aren't already the correct type.

The next() method on the returned iterator may throw a InvalidDataConversionException if the next element cannot be converted to the specified type.

See BeanSession.convertToType(Object, ClassMeta) for a description of valid conversions.

Example:

// Iterate over a list of ObjectMaps. ObjectList l = new ObjectList("[{foo:'bar'},{baz:123}]"); for (ObjectMap m : l.elements(ObjectMap.class)) { // Do something with m. } // Iterate over a list of ints. ObjectList l = new ObjectList("[1,2,3]"); for (Integer i : l.elements(Integer.class)) { // Do something with i. } // Iterate over a list of beans. // Automatically converts to beans. ObjectList l = new ObjectList("[{name:'John Smith',age:45}]"); for (Person p : l.elements(Person.class)) { // Do something with p. }

Type Parameters:

E - The child object type.

Parameters:

childType - The child object type.

Returns:

A new Iterable object over this list.

getClassMeta

public ClassMeta<?> getClassMeta(int index)

Returns the ClassMeta of the class of the object at the specified index.

Parameters:

index - An index into this list, zero-based.

Returns:

The data type of the object at the specified index, or null if the value is null.

toString

public String toString(WriterSerializer serializer)
                throws SerializeException

Serialize this array to a string using the specified serializer.

Parameters:

serializer - The serializer to use to convert this object to a string.

Returns:

This object as a serialized string.

Throws:

SerializeException - If a problem occurred trying to convert the output.

toString

public String toString()

Serialize this array to JSON using the JsonSerializer.DEFAULT serializer.

Overrides:

toString in class AbstractCollection<Object>

serializeTo

public void serializeTo(Writer w)
                 throws IOException,
                        SerializeException

Convenience method for serializing this ObjectList to the specified Writer using the JsonSerializer.DEFAULT serializer.

Parameters:

w - The writer to send the serialized contents of this object.

Throws:

IOException - If a problem occurred trying to write to the writer.

SerializeException - If a problem occurred trying to convert the output.