Now that we know all data types: int, double, char, boolean, String..., our programs should be able to process a lot of data. When we have a large amount of data, keyboard is not the best device to input the data. More than often, we can use files to save data for our programs.
B. Input/Output with data files
Data files are plain text files, a common suffix is .txt or .data. These files does not have any font or size formatting information.
Data files often have multiple data columns, separated by commas, white spaces or other characters. These separators are called "delimiters".
We can use Scanner class and a FileReader class to read a data file. We can specify what delimiter to use.