Class ImmutableMap.Builder<K,​V>

  • Direct Known Subclasses:
    ImmutableBiMap.Builder, ImmutableSortedMap.Builder
    Enclosing class:
    ImmutableMap<K,​V>

    public static class ImmutableMap.Builder<K,​V>
    extends java.lang.Object
    A builder for creating immutable map instances, especially public static final maps ("constant maps"). Example:
    
     static final ImmutableMap<String, Integer> WORD_TO_INT =
         new ImmutableMap.Builder<String, Integer>()
             .put("one", 1)
             .put("two", 2)
             .put("three", 3)
             .buildOrThrow();
     

    For small immutable maps, the ImmutableMap.of() methods are even more convenient.

    By default, a Builder will generate maps that iterate over entries in the order they were inserted into the builder, equivalently to LinkedHashMap. For example, in the above example, WORD_TO_INT.entrySet() is guaranteed to iterate over the entries in the order "one"=1, "two"=2, "three"=3, and keySet() and values() respect the same order. If you want a different order, consider using ImmutableSortedMap to sort by keys, or call orderEntriesByValue(Comparator), which changes this builder to sort entries by value.

    Builder instances can be reused - it is safe to call buildOrThrow() multiple times to build multiple maps in series. Each map is a superset of the maps created before it.

    Since:
    2.0
    • Field Detail

      • valueComparator

        @CheckForNull
        java.util.Comparator<? super V> valueComparator
      • entries

        java.util.Map.Entry<K,​V>[] entries
      • size

        int size
      • entriesUsed

        boolean entriesUsed
    • Constructor Detail

      • Builder

        public Builder()
        Creates a new builder. The returned builder is equivalent to the builder generated by ImmutableMap.builder().
      • Builder

        Builder​(int initialCapacity)
    • Method Detail

      • ensureCapacity

        private void ensureCapacity​(int minCapacity)
      • put

        public ImmutableMap.Builder<K,​V> put​(K key,
                                                   V value)
        Associates key with value in the built map. Duplicate keys are not allowed, and will cause build() to fail.
      • put

        public ImmutableMap.Builder<K,​V> put​(java.util.Map.Entry<? extends K,​? extends V> entry)
        Adds the given entry to the map, making it immutable if necessary. Duplicate keys are not allowed, and will cause build() to fail.
        Since:
        11.0
      • putAll

        public ImmutableMap.Builder<K,​V> putAll​(java.util.Map<? extends K,​? extends V> map)
        Associates all of the given map's keys and values in the built map. Duplicate keys are not allowed, and will cause build() to fail.
        Throws:
        java.lang.NullPointerException - if any key or value in map is null
      • putAll

        public ImmutableMap.Builder<K,​V> putAll​(java.lang.Iterable<? extends java.util.Map.Entry<? extends K,​? extends V>> entries)
        Adds all of the given entries to the built map. Duplicate keys are not allowed, and will cause build() to fail.
        Throws:
        java.lang.NullPointerException - if any key, value, or entry is null
        Since:
        19.0
      • orderEntriesByValue

        public ImmutableMap.Builder<K,​V> orderEntriesByValue​(java.util.Comparator<? super V> valueComparator)
        Configures this Builder to order entries by value according to the specified comparator.

        The sort order is stable, that is, if two entries have values that compare as equivalent, the entry that was inserted first will be first in the built map's iteration order.

        Throws:
        java.lang.IllegalStateException - if this method was already called
        Since:
        19.0
      • build

        public ImmutableMap<K,​V> build()
        Returns a newly-created immutable map. The iteration order of the returned map is the order in which entries were inserted into the builder, unless orderEntriesByValue(java.util.Comparator<? super V>) was called, in which case entries are sorted by value.

        Prefer the equivalent method buildOrThrow() to make it explicit that the method will throw an exception if there are duplicate keys. The build() method will soon be deprecated.

        Throws:
        java.lang.IllegalArgumentException - if duplicate keys were added
      • buildOrThrow

        public ImmutableMap<K,​V> buildOrThrow()
        Returns a newly-created immutable map, or throws an exception if any key was added more than once. The iteration order of the returned map is the order in which entries were inserted into the builder, unless orderEntriesByValue(java.util.Comparator<? super V>) was called, in which case entries are sorted by value.
        Throws:
        java.lang.IllegalArgumentException - if duplicate keys were added
        Since:
        31.0