Files are means of persistance. Peristance refers to the ability to keep, store & contain data, without a running program.
When a program stops executing, all of the variables, data and state are effectively wiped from memory.
Files have different formats - some are human readable such as .txt files others are meant to be read by a machine such as a .class file.
We will be working with .csv files.
A .csv file is structured as a table, meaning that it has columns & rows, each row representing an entity.
Each of the rows in the .csv file above represents a movie (entity) from IMDB.
The approach to reading files in java is to refer to the file on disk by its path.
The file is afterwards read by a scanner in a loop and each loop iteration refers to a line in the file.
Files can both be read word by word - or in our context line by line.
In the example we will be consuming a file line by line and printing it to the screen.
Refer to the file on disk
Read it with a scanner
While the scanners has input
Print the file
New directory created for resources such as data files
File placed in the folder (dragged and dropped)
package algorithms.data.structures;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class FileReader {
public static void main(String[] args){
try{
File filmFile = new File("resources/film-imdb.csv");
Scanner sc = new Scanner(filmFile);
while(sc.hasNextLine()){
String movieDetails = sc.nextLine();
System.out.println(movieDetails);
}
}catch(FileNotFoundException e){
System.out.println("Could not find file");
}
}
}End product:
A console based program that reads a data-set and provides the user with detailed insight about movies
FileReader: A class that reads a file with a method that returns an arraylist of movie objects
(1) Implement functionality such that you can print each movie string from the film-imdb.csv file
(2) Refactor the code such that each movie are stored as Movie objects in an arraylist
AnalysisEngine
An object that instantiates & calls the FileReader method.
AnalysisEngine implements methods to find answers for the following questions:
- What movie has the longest name?
- How many movies are from the Star Trek franchise?
- What is the average length for a movie in hours?
- What is the highest amount of words in a movie title from the list?
- Example:
- Wagon master has 2 words
- Tie Me Up! Tie Me Down! has 6 words
- Tie Me Up! Tie Me Down! has the maximum amount of words of this 2 title example
- How many movies won awards?
- What year won the most awards?
- How many movies are sequals?
- What movie has the most unique consonant?
- Write a menu that lets the user choose what question he/she wants answered