Module nl.basjes.collections.prefixmap
Package nl.basjes.collections

Interface PrefixMap<V extends Serializable>

  • All Superinterfaces:
    Map<String,​V>, Serializable
    All Known Implementing Classes:
    ASCIIPrefixMap, StringPrefixMap
    public interface PrefixMap<V extends Serializable>
extends Serializable, Map<String,​V>

    An object that maps String prefixes to values. A PrefixMap cannot contain duplicate prefixes; each prefix can map to at most one value.

    The PrefixMap is a key-value type collection where the key is assumed to be the prefix of the String for which later an answer is requested.

    So the retrieval of the value is based on a startsWith() check of the requested input against each of the stored prefixes. The value associated with the selected prefix is then returned.

    An example use case is where mobile phone device models of a certain brand all start with the same substring. This data structure can be used to efficiently retrieve the best fitting prefix to find the associated value (i.e. the brand of the device).

    Note that implementations may be constructed to match either case sensitive or case insensitive.

    • Method Detail

      • size

        int size()
        Specified by:
        size in interface Map<String,​V extends Serializable>
        Returns:
        the number of prefix-value mappings in this prefixmap

      • containsPrefix

        boolean containsPrefix​(String prefix)

        Returns true if this map contains an exact mapping for the specified prefix.

        Note that implementations may be constructed to match either case sensitive or case insensitive.

        Parameters:
        prefix - prefix whose presence in this prefixmap is to be checked
        Returns:
        true if this map contains an the exact mapping for the specified prefix.

      • putAll

        default void putAll​(Map<? extends String,​? extends V> prefixesAndValues)
        Copies all of the mappings from the specified map to this prefixmap.
        Specified by:
        putAll in interface Map<String,​V extends Serializable>
        Parameters:
        prefixesAndValues - mappings to be stored in this map
        Throws:
        NullPointerException - if one or more of the prefixes or values are null. If this happens the PrefixMap is in an undefined state.

      • put

        V put​(String prefix,
      V value)

        Stored the specified value as the result for the specified prefix.

        If for the specified prefix previously a value was present then the old value is replaced with the new value and the old value is returned.

        Note that implementations may be constructed to store this value for either case sensitive or case insensitive matching during retrieval.

        Specified by:
        put in interface Map<String,​V extends Serializable>
        Parameters:
        prefix - prefix with which the specified value is to be associated
        value - value to be associated with the specified prefix
        Returns:
        the previous value of the specified prefix, or null if there was no mapping for prefix.
        Throws:
        NullPointerException - if either the prefix or value are null. If this happens the PrefixMap is unchanged.

      • remove

        default V remove​(String prefix)

        Removes the mapping for a prefix if present.

        Note that implementations may be constructed to remove either case sensitive (only this exact value) or case insensitive (all case variations).

        Parameters:
        prefix - prefix whose mapping is to be removed from the prefixmap
        Returns:
        the previous value associated with prefix (may be null).
        Throws:
        UnsupportedOperationException - if not implemented.

      • get

        V get​(String prefix)

        Return the value of the exact matching prefix.

        The value returned is the stored prefix for which is true: input.equals(prefix).

        Note that implementations may be constructed to match either case sensitive or case insensitive.

        Parameters:
        prefix - The string for which we need value of the stored prefix
        Returns:
        The value, null if not found.

      • get

        default V get​(Object prefix)

        Return the value of the exact matching prefix.

        The value returned is the stored prefix for which is true: input.equals(prefix).

        Note that implementations may be constructed to match either case sensitive or case insensitive.

        Specified by:
        get in interface Map<String,​V extends Serializable>
        Parameters:
        prefix - The string for which we need the stored value
        Returns:
        The value, null if not found.

      • getShortestMatch

        V getShortestMatch​(String input)

        Return the value of the shortest matching prefix.

        The value returned is the shortest stored prefix for which is true: input.startsWith(prefix).

        Note that implementations may be constructed to match either case sensitive or case insensitive.

        Parameters:
        input - The string for which we need value of the stored prefix
        Returns:
        The value, null if not found.

      • getLongestMatch

        V getLongestMatch​(String input)

        Return the value of the longest matching prefix.

        The value returned is the longest stored prefix for which is true: input.startsWith(prefix).

        Note that implementations may be constructed to match either case sensitive or case insensitive.

        Parameters:
        input - The string for which we need value of the stored prefix
        Returns:
        The value, null if not found.