[Chapter 23] 23.2 java.beans.BeanInfo (JDK 1.1)

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| Chapter 23 The java.beans Package |

## 23.2 java.beans.BeanInfo (JDK 1.1)

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The `BeanInfo` interface defines the methods that a class must implement in order to export information about a Java bean. The `Introspector` class knows how to obtain all the basic information required about a bean. A bean that wants to be more "programmer-friendly" may provide a class that implements this interface, however, in order to provide additional information about itself (such as an icon and description strings for each of its properties, events, and methods). Note that a bean developer defines a class that implements the methods of this interface. Typically only builder applications and similar tools actually invoke the methods defined here.

The methods `getBeanDescriptor()`, `getEventSetDescriptors()`, `getPropertyDescriptors()`, and `getMethodDescriptors()` should return appropriate descriptor objects for the bean, or `null`, if the bean does not provide explicit bean, event set, property, or method descriptor objects. The `getDefaultEventIndex()` and `getDefaultPropertyIndex()` methods return values that specify the "default" event and property--i.e., that are most likely to be of interest to a programmer using the bean. These methods should return -1 if there are no defaults.

The `getIcon()` method should return an image object suitable for representing the bean in a palette or menu of available beans. The argument passed to this method is one of the four constants defined by the class; it specifies the type and size of icon requested. If the requested icon cannot be provided, `getIcon()` should return `null`.

A `BeanInfo` class is allowed to return `null` or -1 if it cannot provide the requested information. In this case, the `Introspector` class provides basic values for the omitted information from its own introspection of the bean. See `SimpleBeanInfo` for a trivial implementation of this interface, suitable for convenient subclassing.

    public abstract interface BeanInfo {
        // Constants
                public static final int ICON_COLOR_16x16;
                public static final int ICON_COLOR_32x32;
                public static final int ICON_MONO_16x16;
                public static final int ICON_MONO_32x32;
        // Public Instance Methods
                public abstract BeanInfo[] getAdditionalBeanInfo();
                public abstract BeanDescriptor getBeanDescriptor();
                public abstract int getDefaultEventIndex();
                public abstract int getDefaultPropertyIndex();
                public abstract EventSetDescriptor[] getEventSetDescriptors();
                public abstract Image getIcon(int iconKind);
                public abstract MethodDescriptor[] getMethodDescriptors();
                public abstract PropertyDescriptor[] getPropertyDescriptors();
    }

### Implemented By:

SimpleBeanInfo

### Returned By:

BeanInfo.getAdditionalBeanInfo(), Introspector.getBeanInfo(), SimpleBeanInfo.getAdditionalBeanInfo()

java.beans.BeanDescriptor (JDK 1.1) |  | java.beans.Beans (JDK 1.1)