taglib-bean

The <bean:define> tag differs from <jsp:useBean> in several ways, including:

• Unconditionally creates (or replaces) a bean under the specified identifier.
• Can create a bean with the value returned by a property getter of a different bean (including properties referenced with a nested and/or indexed property name).
• Can create a bean whose contents is a literal string (or the result of a runtime expression) specified by the value attribute.
• Does not support nested content (such as <jsp:setProperty> tags) that are only executed if a bean was actually created.

If you use another tag to create the body content (e.g. bean:write), that tag must return a non-empty String. An empty String equates to an empty body or a null String, and a new scripting variable cannot be defined as null. Your bean must return a non-empty String, or the define tag must be wrapped within a logic tag to test for an empty or null value.