ALBERLAU blog

Imagine there is Account class that holds IBAN, currency, and balance. Customer wants to display combo of accounts that displays options in format LT025010200020000141 LTL(1000.23) . Most quick solution probably is to place :

getDisplayInFormat1() { return iban+" "+currency+"("+balance+")";}

method inside of Acount class. Of course Account class will soon be overwhelmed with getDisplayInFormat2, getDisplayInFormat3 and so on methods with view related information, possibly with style:red to indicate insufficient balance.

Next solution is to create some DropDownAccountDecorator. Usage is below:

  List<Account> acc = cpFacade.loadAccounts(user);
  List decoratedAcc = ListDecorator.getInstance(new DropDownAccountDecorator(), acc);
  

DropDownAccountDecorator source :

import net.sf.cglib.proxy.Enhancer;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;

public class DropDownAccountDecorator implements IListItemDecorator,Serializable {
 private boolean hideBalance;

 @Override
 public Object decorate(final Object o) {
  return Enhancer.create(o.getClass(), new MethodInterceptor() {
   @Override
   public Object intercept(Object obj, Method mth, Object[] args, MethodProxy mpx) throws Throwable {
    Object res = mth.invoke(o, args);
    String mname = mth.getName();
    if (!mname.equals("getDisplay")) {
     return res;
    }
    Account acc = (Account) obj;
    String display;
    if (AccStates.BLOCKED.equals(acc.getAccState())) {
     display = String.format("%s (%1.2f %s blocked)", acc.getName(), acc.getTotalBalance(), acc.getCurrencyDetail().get(0).getCurrency().getCode());
    } else {
     if(hideBalance) {
      display =  String.format("%s %s", acc.getName(), acc.getCurrencyDetail().get(0).getCurrency().getCode());
     } else {
      display = String.format("%s (%1.2f %s)", acc.getName(), acc.getTotalBalance(), acc.getCurrencyDetail().get(0).getCurrency().getCode());
     }
    }
    return display;
   }
  });
 }

 public void setHideBalance(boolean b) {
  this.hideBalance=b;
 }
}

Code uses ListProxy infrastructure from my previous post.