Setting a List indexed property with BeanUtils

Question

I'm attempting to use BeanUtils to interact with a Java bean similar to the following:

public class Bean {
    private List<Integer> prices = new LinkedList<Integer>();

    public List<Integer> getPrices() {
        return prices;
    }
}

According to the BeanUtils documentation, BeanUtils does support indexed properties that are Lists:

As an extension to the JavaBeans specification, the BeanUtils package considers any property whose underlying data type is java.util.List (or an implementation of List) to be indexed as well.

However, let's say I try to do something like the following:

Bean bean = new Bean();

// Add nulls to make the list the correct size
bean.getPrices().add(null);
bean.getPrices().add(null);

BeanUtils.setProperty(bean, "prices[0]", 123);
PropertyUtils.setProperty(bean, "prices[1]", 456);

System.out.println("prices[0] = " + BeanUtils.getProperty(bean, "prices[0]"));
System.out.println("prices[1] = " + BeanUtils.getProperty(bean, "prices[1]"));

The output is:

prices[0] = null
prices[1] = 456

Why is BeanUtils.setProperty() unable to set the indexed property, while PropertyUtils.setProperty() can? Does BeanUtils not support type conversion for objects inside Lists?

Answer 1

BeanUtils requires a setter method for it to work. Your Bean class is missing the setter method for prices, add this and rerun your code, it should work fine:-

public void setPrices(List<Integer> prices) {
    this.prices = prices;
}