Create InstructureDeque.java

Author: CodeInSuits

InstructureDeque.java

@@ -0,0 +1,75 @@
+/*
+ * An interface describing the operations to support the "double-ended
+ * queue" abstract data type, known as the deque and pronounced as
+ * "deck". Elements can be added to and removed from the head and the
+ * tail of the deque.
+ *
+ * In this interface, elements can be any Object type or null.
+ */
+public interface InstructuresDeque
+{
+  /*
+   * Returns the number of elements in the deque.
+   */
+  int size();
+
+  /*
+   * Returns `true` if there are no elements in the deque.
+   */
+  boolean isEmpty();
+
+  /*
+   * Adds the given element to the top of the deque. (This operation
+   * is known as "push" for stacks, and "unshift" for sequences.)
+   *
+   * Throws IllegalStateException if this method is called when the
+   * deque is full.
+   */
+  void addTop(Object element);
+
+  /*
+   * Adds the given element to the bottom of the deque. (This
+   * operation is known as "enqueue [as a verb]" for queues.)
+   *
+   * Throws IllegalStateException if this method is called when the
+   * deque is full.
+   */
+  void addBottom(Object element);
+
+  /*
+   * Removes the deque's top-most element, returning its value. (This
+   * operation is known as "pop" for stacks, "shift" for sequences,
+   * and "dequeue [as a verb]" for queues.)
+   *
+   * Throws IllegalStateException if this method is called when the
+   * deque is empty.
+   */
+  Object removeTop();
+
+  /*
+   * Removes the deque's bottom-most element, returning its value.
+   *
+   * Throws IllegalStateException if this method is called when the
+   * deque is empty.
+   */
+  Object removeBottom();
+
+  /*
+   * If the deque is non-empty, returns the value of the deque's
+   * top-most element without removing it; returns null
+   * otherwise. (This operation is known as "peek" for stacks, and
+   * "first" for sequences.)
+   *
+   * Unlike `removeTop`, `top` does not throw an exception.
+   */
+  Object top();
+
+  /*
+   * If the deque is non-empty, returns the value of the deque's
+   * bottom-most element without removing it; returns null
+   * otherwise. (This operation is known as "last" for sequences.)
+   *
+   * Unlike `removeBottom`, `bottom` does not throw an exception.
+   */
+  Object bottom();
+}