Rezha Julio

The Hard Coded Chemist

Get more with collections!

In addition to Python’s built-in data structures (such as tuples, dicts, and lists), a library module called collections provides data structures with additional features, some of which are specializations of the built-in ones. Import the module: import collections Specialized container datatypes are usually dict subclasses or wrappers around other classes like lists, tuples, etc. Notable implementations are : the Counter class used for counting hashable objects. defaultdict class used as a faster implementation of a specialised dictionary. Continue reading

Translating Scanner tokens into primitive types

The Scanner class can be used to break an input into tokens separated by delimiters. Scanner also has methods to translate each token into one of Java’s primitive types. Delimiters are string patterns and are set in the following way: Scanner s = new Scanner(input); s.useDelimiter(pattern); If we need to read a file containing a set of integers, and calculate the total, we can use Scanner’s nextInt method: int sum = 0; //create a new instance of Scanner Scanner s = new Scanner( new BufferedReader( new FileReader("in. Continue reading

Listing a file system's root directories

Using the static FileSystems class, you can get the default FileSystem (note the missing s) through the getDefault() method. The getRootDirectories() method of FileSystem can be used to acquire a list of root directories on a file system. An object of type Iterable is returned, so the directories can be iterated over in the following way: FileSystem sys = FileSystems.getDefault(); Iterable<Path> d = sys.getRootDirectories(); for (Path name: d) { System.out.println(name); } This is available from Java 1. Continue reading

The Console class

The class provides methods to access the character-based console device, if any, associated with the current Java Virtual Machine. This class is attached to the System console internally. Console class provide means to read text and passwords from the console. To read a line as a String: Console console = System.console(); String myString = console.readLine(); To read a password as an array of chars: Console console = System.console(); char[] pw = console. Continue reading