gistfile1.java

	@Test public void
	print_transactions_in_reverse_chronological_order() {
		given(clock.timeAsString()).willReturn("01/04/2014", "02/04/2014", "10/04/2014");

		account.deposit(1000);
		account.withdraw(100);
		account.deposit(500);

		account.printStatement();

		InOrder inOrder = Mockito.inOrder(console);
		inOrder.verify(console).printLine("DATE | AMOUNT | BALANCE");
		inOrder.verify(console).printLine("10/04/2014 | 500.00 | 1400.00");
		inOrder.verify(console).printLine("02/04/2014 | -100.00 | 900.00");
		inOrder.verify(console).printLine("01/04/2014 | 1000.00 | 1000.00");
	}
	
public class StatementPrinter {

	public static final String STATEMENT_HEADER = "DATE | AMOUNT | BALANCE";

	private Console console;

	public StatementPrinter(Console console) {
		this.console = console;
	}

	public void print(List<Transaction> transactions) {
		printStatementHeader();
		printStatementLines(transactions);
	}

	private void printStatementHeader() {
		console.printLine(STATEMENT_HEADER);
	}

	private void printStatementLines(List<Transaction> transactions) {
		List<String> statementLines = statementLinesFor(transactions);
		reverse(statementLines).forEach(console::printLine);
	}

	private List<String> statementLinesFor(List<Transaction> transactions) {
		final AtomicInteger runningBalance = new AtomicInteger(0);
		return transactions.stream()
							.map(t -> statementLine(runningBalance, t))
							.collect(toList());
	}

	private String statementLine(AtomicInteger runningBalance, Transaction t) {
		return
			t.date() +
			" | " +
			formatWithTwoDecimalDigits(t.amount()) +
			" | " +
			formatWithTwoDecimalDigits(runningBalance.addAndGet(t.amount()));
	}

	private String formatWithTwoDecimalDigits(int amount) {
		DecimalFormat decimalFormat = new DecimalFormat("#.00");
		return decimalFormat.format(amount);
	}
}