Design and Architectural Principles - Java 8 Lambdas - page 128

checkCreditHistory ();
checkIncomeHistory ();
reportFindings ();

}

protected protected abstract abstract void void checkIdentity () throws throws ApplicationDenied ;

protected protected abstract abstract void void checkIncomeHistory () throws throws ApplicationDenied ;

protected protected abstract abstract void void checkCreditHistory () throws throws ApplicationDenied ;

private private void void reportFindings () {

CompanyLoanApplication implements checkIdentity by looking up information in a
company registration database, such as Companies House. checkIncomeHistory would in-
volve assessing existing profit and loss statements and balance sheets for the firm. check-
CreditHistory would look into existing bad and outstanding debts.

PersonalLoanApplication implements checkIdentity by analyzing the paper statements
that the client has been required to provide in order to check that the client's address exists.
checkIncomeHistory involves assessing pay slips and checking whether the person is still
employed. checkCreditHistory delegates to an external credit payment provider.

EmployeeLoanApplication is just PersonalLoanApplication with no employment his-
tory checking. Conveniently, our bank already checks all its employees' income histories
when hiring them ( Example 8-22 ).

Example 8-22. A special case of an an employee applying for a loan
public public class class EmployeeLoanApplication EmployeeLoanApplication extends extends PersonalLoanApplication {

@Override
protected

protected void void checkIncomeHistory () {

// They work for us!

}

}

With lambda expressions and method references, we can think about the template method
pattern in a different light and also implement it differently. What the template method pat-
tern is really trying to do is compose a sequence of method calls in a certain order. If we rep-
resent the functions as functional interfaces and then use lambda expressions or method ref-
erences to implement those interfaces, we can gain a huge amount of flexibility over using