org.apache.solr.common.util

Class NamedList<T>

java.lang.Object

org.apache.solr.common.util.NamedList<T>

All Implemented Interfaces:

Serializable, Cloneable, Iterable<Map.Entry<String,T>>

Direct Known Subclasses:

SimpleOrderedMap

public class NamedList<T>
extends Object
implements Cloneable, Serializable, Iterable<Map.Entry<String,T>>

A simple container class for modeling an ordered list of name/value pairs.

Unlike Maps:

• Names may be repeated
• Order of elements is maintained
• Elements may be accessed by numeric index
• Names and Values can both be null

A NamedList provides fast access by element number, but not by name.

When a NamedList is serialized, order is considered more important than access by key, so ResponseWriters that output to a format such as JSON will normally choose a data structure that allows order to be easily preserved in various clients (i.e. not a straight map). If access by key is more important for serialization, see SimpleOrderedMap, or simply use a regular Map

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	NamedList.NamedListEntry<T> Helper class implementing Map.Entry<String, T> to store the key-value relationship in NamedList (the keys of which are String-s)

Field Summary

Fields

Modifier and Type	Field and Description
protected List<Object>	nvPairs

Constructor Summary

Constructors

Constructor and Description
NamedList() Creates an empty instance
NamedList(List<Object> nameValuePairs) Deprecated. Use NamedList(java.util.Map.Entry[]) for the NamedList instantiation
NamedList(Map.Entry<String,? extends T>[] nameValuePairs) Creates a NamedList instance containing the "name,value" pairs contained in the Entry[].

Method Summary

Methods

Modifier and Type	Method and Description
void	add(String name, T val) Adds a name/value pair to the end of the list.
boolean	addAll(Map<String,T> args) Iterates over the Map and sequentially adds it's key/value pairs
boolean	addAll(NamedList<T> nl) Appends the elements of the given NamedList to this one.
void	clear()
NamedList<T>	clone() Makes a shallow copy of the named list.
boolean	equals(Object obj)
Object	findRecursive(String... args) Recursively parses the NamedList structure to arrive at a specific element.
T	get(String name) Gets the value for the first instance of the specified name found.
T	get(String name, int start) Gets the value for the first instance of the specified name found starting at the specified index.
List<T>	getAll(String name) Gets the values for the the specified name
String	getName(int idx) The name of the pair at the specified List index
T	getVal(int idx) The value of the pair at the specified List index
int	hashCode()
int	indexOf(String name, int start) Scans the list sequentially beginning at the specified index and returns the index of the first pair with the specified name.
Iterator<Map.Entry<String,T>>	iterator() Support the Iterable interface
T	remove(int idx) Removes the name/value pair at the specified index.
T	remove(String name) NOTE: this runs in linear time (it scans starting at the beginning of the list until it finds the first pair with the specified name).
List<T>	removeAll(String name) Removes and returns all values for the specified name.
Boolean	removeBooleanArg(String name) Used for getting a boolean argument from a NamedList object.
Collection<String>	removeConfigArgs(String name) Used for getting one or many arguments from NamedList objects that hold configuration parameters.
void	setName(int idx, String name) Modifies the name of the pair at the specified index.
T	setVal(int idx, T val) Modifies the value of the pair at the specified index.
int	size() The total number of name/value pairs
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

nvPairs

protected final List<Object> nvPairs

Constructor Detail

NamedList

public NamedList()

Creates an empty instance

NamedList

public NamedList(Map.Entry<String,? extends T>[] nameValuePairs)

Creates a NamedList instance containing the "name,value" pairs contained in the Entry[].

Modifying the contents of the Entry[] after calling this constructor may change the NamedList (in future versions of Solr), but this is not guaranteed and should not be relied upon. To modify the NamedList, refer to add(String, Object) or remove(String).

Parameters:

nameValuePairs - the name value pairs

NamedList

@Deprecated
public NamedList(List<Object> nameValuePairs)

Deprecated. Use NamedList(java.util.Map.Entry[]) for the NamedList instantiation

Creates an instance backed by an explicitly specified list of pairwise names/values.

When using this constructor, runtime type safety is only guaranteed if all even numbered elements of the input list are of type "T".

Parameters:

nameValuePairs - underlying List which should be used to implement a NamedList

Method Detail

size

public int size()

The total number of name/value pairs

getName

public String getName(int idx)

The name of the pair at the specified List index

Returns:

null if no name exists

getVal

public T getVal(int idx)

The value of the pair at the specified List index

Returns:

may be null

add

public void add(String name,
       T val)

Adds a name/value pair to the end of the list.

setName

public void setName(int idx,
           String name)

Modifies the name of the pair at the specified index.

setVal

public T setVal(int idx,
       T val)

Modifies the value of the pair at the specified index.

Returns:

the value that used to be at index

remove

public T remove(int idx)

Removes the name/value pair at the specified index.

Returns:

the value at the index removed

indexOf

public int indexOf(String name,
          int start)

Scans the list sequentially beginning at the specified index and returns the index of the first pair with the specified name.

Parameters:

name - name to look for, may be null

start - index to begin searching from

Returns:

The index of the first matching pair, -1 if no match

get

public T get(String name)

Gets the value for the first instance of the specified name found.

NOTE: this runs in linear time (it scans starting at the beginning of the list until it finds the first pair with the specified name).

Returns:

null if not found or if the value stored was null.

See Also:

indexOf(java.lang.String, int), get(String,int)

get

public T get(String name,
    int start)

Gets the value for the first instance of the specified name found starting at the specified index.

NOTE: this runs in linear time (it scans starting at the specified position until it finds the first pair with the specified name).

Returns:

null if not found or if the value stored was null.

See Also:

indexOf(java.lang.String, int)

getAll

public List<T> getAll(String name)

Gets the values for the the specified name

Parameters:

name - Name

Returns:

List of values

findRecursive

public Object findRecursive(String... args)

Recursively parses the NamedList structure to arrive at a specific element. As you descend the NamedList tree, the last element can be any type, including NamedList, but the previous elements MUST be NamedList objects themselves. A null value is returned if the indicated hierarchy doesn't exist, but NamedList allows null values so that could be the actual value at the end of the path. This method is particularly useful for parsing the response from Solr's /admin/mbeans handler, but it also works for any complex structure. Explicitly casting the return value is recommended. An even safer option is to accept the return value as an object and then check its type. Usage examples: String coreName = (String) response.findRecursive ("solr-mbeans", "CORE", "core", "stats", "coreName"); long numDoc = (long) response.findRecursive ("solr-mbeans", "CORE", "searcher", "stats", "numDocs");

Parameters:

args - One or more strings specifying the tree to navigate.

Returns:

the last entry in the given path hierarchy, null if not found.

toString

public String toString()

Overrides:

toString in class Object

addAll

public boolean addAll(Map<String,T> args)

Iterates over the Map and sequentially adds it's key/value pairs

addAll

public boolean addAll(NamedList<T> nl)

Appends the elements of the given NamedList to this one.

clone

public NamedList<T> clone()

Makes a shallow copy of the named list.

Overrides:

clone in class Object

iterator

public Iterator<Map.Entry<String,T>> iterator()

Support the Iterable interface

Specified by:

iterator in interface Iterable<Map.Entry<String,T>>

remove

public T remove(String name)

NOTE: this runs in linear time (it scans starting at the beginning of the list until it finds the first pair with the specified name).

removeAll

public List<T> removeAll(String name)

Removes and returns all values for the specified name. Returns null if no matches found. This method will return all matching objects, regardless of data type. If you are parsing Solr config options, the removeConfigArgs(String) or removeBooleanArg(String) methods will probably work better.

Parameters:

name - Name

Returns:

List of values

removeBooleanArg

public Boolean removeBooleanArg(String name)

Used for getting a boolean argument from a NamedList object. If the name is not present, returns null. If there is more than one value with that name, or if the value found is not a Boolean or a String, throws an exception. If there is only one value present and it is a Boolean or a String, the value is removed and returned as a Boolean. If an exception is thrown, the NamedList is not modified. See removeAll(String) and removeConfigArgs(String) for additional ways of gathering configuration information from a NamedList.

Parameters:

name - The key to look up in the NamedList.

Returns:

The boolean value found.

Throws:

SolrException - If multiple values are found for the name or the value found is not a Boolean or a String.

removeConfigArgs

public Collection<String> removeConfigArgs(String name)
                                    throws SolrException

Used for getting one or many arguments from NamedList objects that hold configuration parameters. Finds all entries in the NamedList that match the given name. If they are all strings or arrays of strings, remove them from the NamedList and return the individual elements as a Collection. Parameter order will be preserved if the returned collection is handled as an ArrayList. Throws SolrException if any of the values associated with the name are not strings or arrays of strings. If exception is thrown, the NamedList is not modified. Returns an empty collection if no matches found. If you need to remove and retrieve all matching items from the NamedList regardless of data type, use removeAll(String) instead. The removeBooleanArg(String) method can be used for retrieving a boolean argument.

Parameters:

name - The key to look up in the NamedList.

Returns:

A collection of the values found.

Throws:

SolrException - If values are found for the input key that are not strings or arrays of strings.

clear

public void clear()

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object