org.apache.reef.io

Interface ExternalMap<T>

Type Parameters:

T - the entry type of the map

All Known Implementing Classes:

CodecRamMap, RamMap

public interface ExternalMap<T>

A Map interface for data that can be swapped out to other processes, managed by native code, paged to disk, stored remotely, etc...

Method Summary

Methods

Modifier and Type	Method and Description
boolean	containsKey(CharSequence key)
T	get(CharSequence key) Element access
Iterable<Map.Entry<CharSequence,T>>	getAll(Set<? extends CharSequence> keys)
T	put(CharSequence key, T value) Put a record into the map
void	putAll(Map<? extends CharSequence,? extends T> m) Copies all of the mappings from the specified map to this map (optional operation).
T	remove(CharSequence key) Removes the mapping for a key from this map if it is present (optional operation).

Method Detail

containsKey

boolean containsKey(CharSequence key)

Parameters:

key -

Returns:

true, if an entry with the given key exists

get

T get(CharSequence key)

Element access

Parameters:

key -

Returns:

the object stored under key nor null if no such object exists

put

T put(CharSequence key,
    T value)

Put a record into the map

Parameters:

key -

value -

Returns:

the previous value associated with key, or null if there was no mapping for key. (A null return can also indicate that the map previously associated null with key, if the implementation supports null values.)

remove

T remove(CharSequence key)

Removes the mapping for a key from this map if it is present (optional operation). More formally, if this map contains a mapping from key k to value v such that (key==null ? k==null : key.equals(k)), that mapping is removed. (The map can contain at most one such mapping.) Returns the value to which this map previously associated the key, or null if the map contained no mapping for the key.

If this map permits null values, then a return value of null does not necessarily indicate that the map contained no mapping for the key; it's also possible that the map explicitly mapped the key to null.

The map will not contain a mapping for the specified key once the call returns.

Parameters:

key - key whose mapping is to be removed from the map

Returns:

the previous value associated with key, or null if there was no mapping for key.

putAll

void putAll(Map<? extends CharSequence,? extends T> m)

Copies all of the mappings from the specified map to this map (optional operation). The effect of this call is equivalent to that of calling put(k, v) on this map once for each mapping from key k to value v in the specified map. The behavior of this operation is undefined if the specified map is modified while the operation is in progress.

Parameters:

m -

getAll

Iterable<Map.Entry<CharSequence,T>> getAll(Set<? extends CharSequence> keys)