类 ListUtils

方法详细资料

• newArrayList

  public static <E> ArrayList<E> newArrayList()

  Creates a mutable, empty ArrayList instance (for Java 6 and earlier).

  Note for Java 7 and later: this method is now unnecessary and should be treated as deprecated. Instead, use the ArrayListconstructor directly, taking advantage of the new "diamond" syntax.

• newArrayList

  public static <E> ArrayList<E> newArrayList(E... elements)

  Creates a mutable ArrayList instance containing the given elements.

• newArrayList

  public static <E> ArrayList<E> newArrayList(Iterator<? extends E> elements)

  Creates a mutable ArrayList instance containing the given elements; a very thin shortcut for creating an empty list and then calling Iterators.addAll(java.util.Collection<T>, java.util.Iterator<? extends T>).

• newArrayList

  public static <E> ArrayList<E> newArrayList(Iterable<? extends E> elements)

  Creates a mutable ArrayList instance containing the given elements;

  Note for Java 7 and later: if elements is a Collection, you don't need this method. Use the ArrayListconstructor directly, taking advantage of the new "diamond" syntax.

• newArrayListWithCapacity

  public static <E> ArrayList<E> newArrayListWithCapacity(int initialArraySize)

  Creates an ArrayList instance backed by an array with the specified initial size; simply delegates to ArrayList.ArrayList(int).

  Note for Java 7 and later: this method is now unnecessary and should be treated as deprecated. Instead, use new ArrayList<>(int) directly, taking advantage of the new "diamond" syntax. (Unlike here, there is no risk of overload ambiguity, since the ArrayList constructors very wisely did not accept varargs.)

  参数:

  initialArraySize - the exact size of the initial backing array for the returned array list ( ArrayList documentation calls this value the "capacity")

  返回:

  a new, empty ArrayList which is guaranteed not to resize itself unless its size reaches initialArraySize + 1

  抛出:

  IllegalArgumentException - if initialArraySize is negative

• newArrayListWithExpectedSize

  public static <E> ArrayList<E> newArrayListWithExpectedSize(int estimatedSize)

  Creates an ArrayList instance to hold estimatedSize elements, plus an unspecified amount of padding; you almost certainly mean to call newArrayListWithCapacity(int) (see that method for further advice on usage).

  Note: This method will soon be deprecated. Even in the rare case that you do want some amount of padding, it's best if you choose your desired amount explicitly.

  参数:

  estimatedSize - an estimate of the eventual List.size() of the new list

  返回:

  a new, empty ArrayList, sized appropriately to hold the estimated number of elements

  抛出:

  IllegalArgumentException - if estimatedSize is negative

• checkNotNull

  public static <T> T checkNotNull(T reference)

  Ensures that an object reference passed as a parameter to the calling method is not null.

  参数:

  reference - an object reference

  返回:

  the non-null reference that was validated

  抛出:

  NullPointerException - if reference is null