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Java common tasks

Parsing and reading

The class java.util.Scanner provides a iterator-like methods to parse input.

For console input:

Scanner scanner = new Scanner(System.in);
int i = scanner.nextInt();

For file input:

Scanner scanner = new Scanner(new File("myNumbers"));
long nextLong = scanner.nextLong();

Note that the .nextLine() method reads and returns the rest of the current line.

Formatting strings

Use String.format().

Fixed width strings

The number between the % and the s gives the fixed width. If negative the the string will be left justified.

String.format("%-15s", s);

Adding leading zeros to integer

String.format("%03d", n);