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| abstract class AbstractCustomer {
protected String name;
public abstract boolean isNil();
public abstract String getName();
}
class RealCustomer extends AbstractCustomer {
public RealCustomer(String name) {
this.name = name;
}
@Override
public String getName() {
return name;
}
@Override
public boolean isNil() {
return false;
}
}
class NullCustomer extends AbstractCustomer {
@Override
public String getName() {
return "Not Available in Customer Database";
}
@Override
public boolean isNil() {
return true;
}
}
class CustomerFactory {
public static final String[] names = {"Rob", "Joe", "Julie"};
public static AbstractCustomer getCustomer(String name) {
for (String s : names) {
if (s.equalsIgnoreCase(name)) {
return new RealCustomer(name);
}
}
return new NullCustomer();
}
}
public class NullObjectPatternDemo {
public static void main(String[] args) {
AbstractCustomer customer1 = CustomerFactory.getCustomer("Rob");
AbstractCustomer customer2 = CustomerFactory.getCustomer("Bob");
AbstractCustomer customer3 = CustomerFactory.getCustomer("Julie");
AbstractCustomer customer4 = CustomerFactory.getCustomer("Laura");
System.out.println("Customers");
System.out.println(customer1.getName());
System.out.println(customer2.getName());
System.out.println(customer3.getName());
System.out.println(customer4.getName());
}
}
|