Developing Java Beans

Indexed Property Access Methods

There is an additional design pattern for indexed properties. The <PropertyType> in the standard property method design pattern may be an array:

public <PropertyType>[] get<PropertyName>();
public void set<PropertyName>(<PropertyType>[] value);

These methods are used to access the entire array of property values at one time. An additional pair of methods can provide access to individual values in the property array. The method signatures for this pattern are:

public <PropertyType> get<PropertyName>(int index);
public void set<PropertyName>(int index, <PropertyType> value);

As with the single value pattern, these methods are allowed to include a throws clause for throwing checked exceptions. Specifically, the indexed methods may throw a java.lang.ArrayIndexOutOfBoundsException if an index is used that is outside the bounds of the property array. Although this is an important aspect of indexed properties, it isn’t required for the indexed properties pattern. Since the indexed properties are considered ordered collections, the indexed get() and set() methods should always declare the ArrayIndexOutOfBoundsException. It might have been better to make it a requirement for this pattern.