org.apache.tools.ant.util

## Class CollectionUtils

- java.lang.Object
- - org.apache.tools.ant.util.CollectionUtils

-     public class CollectionUtils
      extends java.lang.Object

  A set of helper methods related to collection manipulation.
  Since:
    Ant 1.5

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Class and Description
    --- | ---
    `static class` | `CollectionUtils.EmptyEnumeration<E>` An empty enumeration.

  - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static java.util.List` | `EMPTY_LIST` Deprecated.

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `CollectionUtils()`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `static <E> java.util.Enumeration<E>` | `append(java.util.Enumeration<E> e1, java.util.Enumeration<E> e2)` Append one enumeration to another.
    `static <T> java.util.Collection<T>` | `asCollection(java.util.Iterator<? extends T> iter)` Returns a collection containing all elements of the iterator.
    `static <E> java.util.Enumeration<E>` | `asEnumeration(java.util.Iterator<E> iter)` Adapt the specified Iterator to the Enumeration interface.
    `static <E> java.util.Iterator<E>` | `asIterator(java.util.Enumeration<E> e)` Adapt the specified Enumeration to the Iterator interface.
    `static boolean` | `equals(java.util.Dictionary<?,?> d1, java.util.Dictionary<?,?> d2)` Deprecated. since 1.6.x.
    `static boolean` | `equals(java.util.Vector<?> v1, java.util.Vector<?> v2)` Deprecated. since 1.6.x.
    `static java.lang.String` | `flattenToString(java.util.Collection<?> c)` Creates a comma separated list of all values held in the given collection.
    `static int` | `frequency(java.util.Collection<?> c, java.lang.Object o)` Counts how often the given Object occurs in the given collection using equals() for comparison.
    `static <K,V> void` | `putAll(java.util.Dictionary<? super K,? super V> m1, java.util.Dictionary<? extends K,? extends V> m2)` Deprecated. since 1.6.x.

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

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

- - ### Field Detail

    - #### EMPTY_LIST

          @Deprecated
          public static final java.util.List EMPTY_LIST

      Deprecated.
      Collections.emptyList() is Java5+.

  - ### Constructor Detail

    - #### CollectionUtils

          public CollectionUtils()

  - ### Method Detail

    - #### equals

          public static boolean equals(java.util.Vector<?> v1,
                       java.util.Vector<?> v2)

      Deprecated. since 1.6.x.
      Please use Vector.equals() or List.equals().
      Parameters:
        `v1` - the first vector.
        `v2` - the second vector.
      Returns:
        true if the vectors are equal.
      Since:
        Ant 1.5

    - #### equals

          public static boolean equals(java.util.Dictionary<?,?> d1,
                       java.util.Dictionary<?,?> d2)

      Deprecated. since 1.6.x.
      Dictionary does not have an equals. Please use Map.equals().

      Follows the equals contract of Java 2's Map.

      Parameters:
        `d1` - the first directory.
        `d2` - the second directory.
      Returns:
        true if the directories are equal.
      Since:
        Ant 1.5

    - #### flattenToString

          public static java.lang.String flattenToString(java.util.Collection<?> c)

      Creates a comma separated list of all values held in the given collection.
      Parameters:
        `c` - collection to transform
      Returns:
        string representation of the collection
      Since:
        Ant 1.8.0

    - #### putAll

          public static <K,V> void putAll(java.util.Dictionary<? super K,? super V> m1,
                          java.util.Dictionary<? extends K,? extends V> m2)

      Deprecated. since 1.6.x.
      Dictionary does not know the putAll method. Please use Map.putAll().
      Type Parameters:
        `K` - type of the key
        `V` - type of the value
      Parameters:
        `m1` - the to directory.
        `m2` - the from directory.
      Since:
        Ant 1.6

    - #### append

          public static <E> java.util.Enumeration<E> append(java.util.Enumeration<E> e1,
                                            java.util.Enumeration<E> e2)

      Append one enumeration to another. Elements are evaluated lazily.
      Type Parameters:
        `E` - element type
      Parameters:
        `e1` - the first enumeration.
        `e2` - the subsequent enumeration.
      Returns:
        an enumeration representing e1 followed by e2.
      Since:
        Ant 1.6.3

    - #### asEnumeration

          public static <E> java.util.Enumeration<E> asEnumeration(java.util.Iterator<E> iter)

      Adapt the specified Iterator to the Enumeration interface.
      Type Parameters:
        `E` - element type
      Parameters:
        `iter` - the Iterator to adapt.
      Returns:
        an Enumeration.

    - #### asIterator

          public static <E> java.util.Iterator<E> asIterator(java.util.Enumeration<E> e)

      Adapt the specified Enumeration to the Iterator interface.
      Type Parameters:
        `E` - element type
      Parameters:
        `e` - the Enumeration to adapt.
      Returns:
        an Iterator.

    - #### asCollection

          public static <T> java.util.Collection<T> asCollection(java.util.Iterator<? extends T> iter)

      Returns a collection containing all elements of the iterator.
      Type Parameters:
        `T` - element type
      Parameters:
        `iter` - the Iterator to convert
      Returns:
        the collection
      Since:
        Ant 1.8.0

    - #### frequency

          public static int frequency(java.util.Collection<?> c,
                      java.lang.Object o)

      Counts how often the given Object occurs in the given collection using equals() for comparison.
      Parameters:
        `c` - collection in which to search
        `o` - object to search
      Returns:
        frequency
      Since:
        Ant 1.8.0