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package java.util;

/**
 * Marker interface used by {@code List} implementations to indicate that
 * they support fast (generally constant time) random access.  The primary
 * purpose of this interface is to allow generic algorithms to alter their
 * behavior to provide good performance when applied to either random or
 * sequential access lists.
 *
 * <p>The best algorithms for manipulating random access lists (such as
 * {@code ArrayList}) can produce quadratic behavior when applied to
 * sequential access lists (such as {@code LinkedList}).  Generic list
 * algorithms are encouraged to check whether the given list is an
 * {@code instanceof} this interface before applying an algorithm that would
 * provide poor performance if it were applied to a sequential access list,
 * and to alter their behavior if necessary to guarantee acceptable
 * performance.
 *
 * <p>It is recognized that the distinction between random and sequential
 * access is often fuzzy.  For example, some {@code List} implementations
 * provide asymptotically linear access times if they get huge, but constant
 * access times in practice.  Such a {@code List} implementation
 * should generally implement this interface.  As a rule of thumb, a
 * {@code List} implementation should implement this interface if,
 * for typical instances of the class, this loop:
 * <pre>
 *     for (int i=0, n=list.size(); i &lt; n; i++)
 *         list.get(i);
 * </pre>
 * runs faster than this loop:
 * <pre>
 *     for (Iterator i=list.iterator(); i.hasNext(); )
 *         i.next();
 * </pre>
 *
 * <p>This interface is a member of the
 * <a href="{@docRoot}/java.base/java/util/package-summary.html#CollectionsFramework">
 * Java Collections Framework</a>.
 *
 * @since 1.4
 */
public interface RandomAccess {
}
