Reading data from text files with File and Scanner

Learning objectives

Explain that a file keeps its data after a program stops running, and open a text file for reading by passing a File object, built from the file name, to a Scanner constructor

State what file-reading code requires: import statements for File, IOException and Scanner, and throws IOException in the header of any method that opens the file, so that an invalid file name ends the program

Use the Scanner methods next, nextLine, nextInt, nextDouble and nextBoolean to read values, and predict the InputMismatchException raised when the next value is of the wrong type

Write a while loop controlled by hasNext that reads a file to its end, and close the Scanner once reading is finished

Use split with a delimiter to break a line of text, such as a comma-separated record, into a String array, and convert the parts with Integer.parseInt and Double.parseDouble

Store the values read from a file in an array or an ArrayList, and explain the extra step needed when nextLine is called after nextInt or nextDouble on the same input