Chapter 16, Problem 19PE

Program Plan Intro

Implementation of “remove()” operation

Program plan:

• In a file “HashSet.java”, import necessary packages, and create a class “HashSet”,
  • Declare the array of “Node” type.
  • Declare the necessary variable.
  • Define the constructor to create a hash table,
    • Create an array and set the current size to “0”.
  • Define the method “contains()”,
    • Assign the hash code.
    • Check whether the value is less than “0”,
      • If it is true, assign the negative value.
        • Update the hash value.
        • Assign the current node value.
        • Execute loop till array becomes null,
        • • Check the condition,
            • Return true.
          • Assign the current value.
        • Returns false.
  • Define the method “add()” to add the element to the set,
    • Get the hash code.
    • Check whether the value is less than “0”,
      • If it is true, assign the negative value.
        • Update the hash code.
        • Assign the hash code value to the current node.
        • Execute a loop,
        • • Check the condition,
            • Return false.
          • Assign the next value to the value in the current node.
        • Create a new node.
        • Assign the value to new node value.
        • Assign the value to the next node.
        • Assign the new node value to the bucket.
        • Increment the size.
        • Return true.
  • Define the method “remove()” to remove the object from the set,
    • Get the hash code.
    • Check whether the value is less than “0”,
      • If it is true, assign the negative value.
        • Update the hash code.
        • Assign the hash code value to the current node.
        • Set null to the previous node.
        • Execute a loop,
        • • Check the condition,
            • Check whether the previous node contains null value,
              • If it is true, assign the next node value to the bucket.
                • Otherwise,
                  • Assign the next of the current node value to the next of the previous node value.
                • Decrement the size.
                • Return true.
          • Assign the current node value to the previous node value.
          • Assign the next of the current node value to the current node.
        • Return false.
  • Define the method “iterator ()” to return an iterator that traverse the set elements,
    • Return the object of “HashSetIterator”.
  • Define the method “size ()” to return the size of the set.
  • Create a class “Node”,
    • Declare the object for “Object”.
    • Declare the object of “Node”.
  • Create a class “HashSetIterator” that implements the interface “Iterator”,
    • Declare the necessary variables.
    • Define the constructor to create a hash set that point to the first element of the hash set.
    • Define the method “hasNext()”,
      • Check whether the current node and the next of the current node is not null,
        • If it is true, returns true.
      • Execute a loop,
        • Check whether the bucket contains not null value,
          • If it is true, returns true.
      • Returns false.
    • Define the method “next()”,
      • Check whether the current node is not null value,
        • If it is true, assign the current node value to the previous.
        • Check whether the next reference of the current node is not null,
        • • Assign the next node value to the current node value.
            • • • Otherwise,
                  • Call the method “moveToNext_Bucket()”.
      • Otherwise,
        • Call the method “moveToNext_Bucket()”.
      • Set the Boolean value to true.
      • Return the current node value.
    • Define the method “moveToNext_Bucket()”,
      • Execute the following statement,
        • Increment the index.
        • Check the condition,
        • • Throw an exception “NoSuchElementException”.
            • • • Assign the value.
      • Check the condition at the end of the loop.
    • Define the method “remove()”,
      • Execute for the Boolean value,
        • Throw an exception “UnsupportedOperationException”.
      • Check whether the previous is  null value,
        • Set the current node to null
        • Set the index to “-1”.
        • Call the method “removeFirst()”.
      • Otherwise,
        • Assign the current node value to the object variable.
        • Assign the previous to the current node value.
        • Call the method “remove()”.
      • Decrement the size.
      • Set the previous to null.
      • Set the Boolean variable to false.
    • Define the method “removeFirst()”,
      • Create a loop,
        • Check whether the bucket contains not null value,
        • • If it is true, assign the next value to the bucket.
          • Return nothing.
    • Define the method “remove” with an argument of object parameter,
      • Get the hash code.
      • Check whether the hash code is less than “0”,
        • If it is true, assign the negative value.
      • Update the hash code.
      • Set the bucket index.
      • Create a node.
      • Set the value to null.
      • Execute a loop,
        • Check the condition,
          • Check whether the previous is null,
            • If it is true, assign the next of the current node to the bucket.
          • Otherwise, assign the next of the current node to the next of the previous node.
          • Returns nothing.
        • Assign the current node to the previous node.
        • Set the current element.
• In a file “HashSetTest.java”, import necessary package, and create a class “HashSetTest”,
  • Define the “main()” method,
    • Create an object for “HashSet”.
    • Add the element “Harry” to the set.
    • Add the element “Sue” to the set.
    • Add the element “Nina” to the set.
    • Add the element “Susannah” to the set.
    • Add the element “Larry” to the set.
    • Add the element “Tony” to the set.
    • Create an iterator.
    • Print the actual output.
    • Execute a loop,
      • Print the actual output.
    • Print the symbol “]”.
    • Print the expected output.
    • Create an iterator.
    • Call the method “next()”.
    • Call the method “next()”.
    • Call the method “remove()”.
    • Create an iterator.
    • Print the actual output.
    • Execute a loop,
      • Print the actual output.
    • Print the symbol “]”.
    • Print the expected output.