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Collections Class

layout: default title: Collections Utility Method

In addition to sort(), the Collections class has many other utility methods defined for working with lists.

  • rotate — rotates the elements of the passed-in List by the specified distance.
// Move three elements from the end of the list to the beginning
Collections.rotate(planets, 3);
  • reverse — reverses the order of the elements of the passed-in List.
Collections.reverse(planets);
  • shuffle — randomly shuffles the order of the elements of the passed-in List.
Collections.shuffle(planets);

binarySearch — uses a binary search algorithm to locate the given object within the List.

  • The int return value represents the index of the first match, if found; otherwise a negative number indicating where the object would have occured in the sorted list (see java.util.Collections in the JavaDocs).

  • For the algorithm to work properly, you must sort the List before calling binarySearch.

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