Package com.google.gwt.user.client.ui

## Class PrefixTree

- java.lang.Object
- - java.util.AbstractCollection<java.lang.String>
  - - com.google.gwt.user.client.ui.PrefixTree

- All Implemented Interfaces:
    `java.lang.Iterable<java.lang.String>`, `java.util.Collection<java.lang.String>`

      class PrefixTree
      extends java.util.AbstractCollection<java.lang.String>

  A prefix tree (aka trie).

- - ### Field Summary

    Fields
    Modifier and Type | Field | Description
    --- | --- | ---
    `protected int` | `prefixLength` | Stores the requested prefix length.
    `protected int` | `size` | Store the number of elements contained by this PrefixTree and its sub-trees.
    `protected JavaScriptObject` | `subtrees` | Field to store subtrees in.
    `protected JavaScriptObject` | `suffixes` | Field to store terminal nodes in.

  - ### Constructor Summary

    Constructors
    Constructor | Description
    --- | ---
    `PrefixTree()` | Constructor.
    `PrefixTree​(int prefixLength)` | Constructor.
    `PrefixTree​(int prefixLength, java.util.Collection<java.lang.String> source)` | Constructor.
    `PrefixTree​(java.util.Collection<java.lang.String> source)` | Constructor.

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `boolean` | `add​(java.lang.String s)` | Add a String to the PrefixTree.
    `void` | `clear()` | Initialize native state.
    `boolean` | `contains​(java.lang.Object o)` |
    `boolean` | `contains​(java.lang.String s)` |
    `protected static PrefixTree` | `createPrefixTree​(int prefixLength)` | Used by native methods to create an appropriately blessed PrefixTree.
    `java.util.List<java.lang.String>` | `getSuggestions​(java.lang.String search, int limit)` | Retrieve suggestions from the PrefixTree.
    `java.util.Iterator<java.lang.String>` | `iterator()` |
    `int` | `size()` | Get the number of all elements contained within the PrefixTree.
    `protected void` | `suggestImpl​(java.lang.String search, java.lang.String prefix, java.util.Collection<java.lang.String> output, int limit)` |

    - ### Methods inherited from class java.util.AbstractCollection

      `addAll, containsAll, isEmpty, remove, removeAll, retainAll, toArray, toArray, toString`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

    - ### Methods inherited from interface java.util.Collection

      `equals, hashCode, parallelStream, removeIf, spliterator, stream, toArray`

    - ### Methods inherited from interface java.lang.Iterable

      `forEach`

- - ### Field Detail

    - #### prefixLength

          protected final int prefixLength

      Stores the requested prefix length.

    - #### suffixes

          protected JavaScriptObject suffixes

      Field to store terminal nodes in.

    - #### subtrees

          protected JavaScriptObject subtrees

      Field to store subtrees in.

    - #### size

          protected int size

      Store the number of elements contained by this PrefixTree and its sub-trees.

  - ### Constructor Detail

    - #### PrefixTree

          public PrefixTree()

      Constructor.

    - #### PrefixTree

          public PrefixTree​(java.util.Collection<java.lang.String> source)

      Constructor.
      Parameters:
        `source` - Initialize from another collection

    - #### PrefixTree

          public PrefixTree​(int prefixLength)

      Constructor.
      Parameters:
        `prefixLength` - Smaller prefix length equals faster, more direct searches, at a cost of setup time.

    - #### PrefixTree

          public PrefixTree​(int prefixLength,
                            java.util.Collection<java.lang.String> source)

      Constructor.
      Parameters:
        `prefixLength` - Smaller prefix length equals faster, more direct searches, at a cost of setup time.
        `source` - Initialize from another collection

  - ### Method Detail

    - #### createPrefixTree

          protected static PrefixTree createPrefixTree​(int prefixLength)

      Used by native methods to create an appropriately blessed PrefixTree.
      Parameters:
        `prefixLength` - Smaller prefix length equals faster, more direct searches, at a cost of setup time
      Returns:
        a newly constructed prefix tree

    - #### add

          public boolean add​(java.lang.String s)

      Add a String to the PrefixTree.
      Specified by:
        `add` in interface `java.util.Collection<java.lang.String>`
      Overrides:
        `add` in class `java.util.AbstractCollection<java.lang.String>`
      Parameters:
        `s` - The data to add
      Returns:
        `true` if the string was added, `false` otherwise

    - #### clear

          public void clear()

      Initialize native state.
      Specified by:
        `clear` in interface `java.util.Collection<java.lang.String>`
      Overrides:
        `clear` in class `java.util.AbstractCollection<java.lang.String>`

    - #### contains

          public boolean contains​(java.lang.Object o)

      Specified by:
        `contains` in interface `java.util.Collection<java.lang.String>`
      Overrides:
        `contains` in class `java.util.AbstractCollection<java.lang.String>`

    - #### contains

          public boolean contains​(java.lang.String s)

    - #### getSuggestions

          public java.util.List<java.lang.String> getSuggestions​(java.lang.String search,
                                                                 int limit)

      Retrieve suggestions from the PrefixTree. The number of items returned from getSuggestions may slightly exceed `limit` so that all suffixes and partial stems will be returned. This prevents the search space from changing size if the PrefixTree is used in an interactive manner.
      The returned List is guaranteed to be safe; changing its contents will not affect the PrefixTree.
      Parameters:
        `search` - The prefix to search for
        `limit` - The desired number of results to retrieve
      Returns:
        A List of suggestions

    - #### iterator

          public java.util.Iterator<java.lang.String> iterator()

      Specified by:
        `iterator` in interface `java.util.Collection<java.lang.String>`
      Specified by:
        `iterator` in interface `java.lang.Iterable<java.lang.String>`
      Specified by:
        `iterator` in class `java.util.AbstractCollection<java.lang.String>`

    - #### size

          public int size()

      Get the number of all elements contained within the PrefixTree.
      Specified by:
        `size` in interface `java.util.Collection<java.lang.String>`
      Specified by:
        `size` in class `java.util.AbstractCollection<java.lang.String>`
      Returns:
        the size of the prefix tree

    - #### suggestImpl

          protected void suggestImpl​(java.lang.String search,
                                     java.lang.String prefix,
                                     java.util.Collection<java.lang.String> output,
                                     int limit)