Programming Jakarta Struts, Second Edition

Logic Tags

The Logic tag library contains tags that are useful for managing conditional generation of output text, looping over object collections for repetitive generation of output text, and application flow management. Table 8-5 lists the tags available within the Logic tag library.

Table 8-5. Custom tags within the Logic tag library

Tag name	Description
empty	Evaluate the nested body content of this tag if the requested variable is either null or an empty string.
equal	Evaluate the nested body content of this tag if the requested variable is equal to the specified value.
forward	Forward control to the page specified by the ActionForward entry.
greaterEqual	Evaluate the nested body content of this tag if the requested variable is greater than or equal to the specified value.
greaterThan	Evaluate the nested body content of this tag if the requested variable is greater than the specified value.
iterate	Repeat the nested body content of this tag over a specified collection.
lessEqual	Evaluate the nested body content of this tag if the requested variable is less than or equal to the specified value.
lessThan	Evaluate the nested body content of this tag if the requested variable is less than the specified value.
match	Evaluate the nested body content of this tag if the specified value is an appropriate substring of the requested variable.
messagesNotPresent	Generate the nested body content of this tag if the specified message is not present in this request.