Package org.cis1200

Class FileLineIterator

java.lang.Object
org.cis1200.FileLineIterator
All Implemented Interfaces:
Iterator<String>
public class FileLineIterator extends Object implements Iterator<String>
FileLineIterator provides a useful wrapper around Java's provided BufferedReader and provides practice with implementing an Iterator. Your solution should not read the entire file into memory at once, instead reading a line whenever the next() method is called.

Note: Any IOExceptions thrown by readers should be caught and handled properly. Do not use the ready() method from BufferedReader.

  • Constructor Details

    • FileLineIterator

      public FileLineIterator(BufferedReader reader)
      Creates a FileLineIterator for the reader. Fill out the constructor so that a user can instantiate a FileLineIterator. Feel free to create and instantiate any variables that your implementation requires here. See recitation and lecture notes for guidance.

      If an IOException is thrown by the BufferedReader, then hasNext should return false.

      The only method that should be called on BufferedReader is readLine() and close(). You cannot call any other methods.

      Parameters:
      reader - - A reader to be turned to an Iterator
      Throws:
      IllegalArgumentException - if reader is null

    • FileLineIterator

      public FileLineIterator(String filePath)
      Creates a FileLineIterator from a provided filePath by creating a FileReader and BufferedReader for the file.

      DO NOT MODIFY THIS METHOD.

      Parameters:
      filePath - - a string representing the file
      Throws:
      IllegalArgumentException - if filePath is null or if the file doesn't exist

  • Method Details

    • fileToReader

      public static BufferedReader fileToReader(String filePath)
      Takes in a filename and creates a BufferedReader. See Java's documentation for BufferedReader to learn how to construct one given a path to a file.
      Parameters:
      filePath - - the path to the CSV file to be turned to a BufferedReader
      Returns:
      a BufferedReader of the provided file contents
      Throws:
      IllegalArgumentException - if filePath is null or if the file doesn't exist

    • hasNext

      public boolean hasNext()
      Returns true if there are lines left to read in the file, and false otherwise.

      If there are no more lines left, this method should close the BufferedReader.

      Specified by:
      hasNext in interface Iterator<String>
      Returns:
      a boolean indicating whether the FileLineIterator can produce another line from the file

    • next

      public String next()
      Returns the next line from the file, or throws a NoSuchElementException if there are no more strings left to return (i.e. hasNext() is false).

      This method also advances the iterator in preparation for another invocation. If an IOException is thrown during a next() call, your iterator should make note of this such that future calls of hasNext() will return false and future calls of next() will throw a NoSuchElementException

      Specified by:
      next in interface Iterator<String>
      Returns:
      the next line in the file
      Throws:
      NoSuchElementException - if there is no more data in the file