Checks whether a Collection contains the specified value.
<dsp:containsvar-specvalues="collection"type="search-value"[compareElement="{true|false}"][comparator="comparator-obj"]/>
Attributes
var-spec
An EL variable or scripting variable that captures the Boolean result of the operation, defined with one of these attributes:
Attribute | Description |
|---|---|
| Names an EL variable. When you use |
| Names a scripting variable that scriptlets and expressions can access at runtime. |
values
Specifies the Collection to search. This attribute can specify items of the following data types: primitive array, Object array, Enumeration, Iterator, Collection, and Map.
type
Identifies the data type of the search value, one of the following:
booleanbytechardoublefloatintlongobjectshort
Set this attribute to the search value.
compareElement
If the values attribute is set to a Map, compareElement specifies how to evaluate the Map contents:
false(default): Search all Map keys.true: Search all Map values.
comparator
Set to an instance of java.util.Comparator that you define. Use a comparator to compare specific portions of one element to another. If no comparator is specified, the entire first item is compared to a portion of the second.
Usage Notes
dsp:contains checks whether a given value is contained within the specified Collection . When you use this tag, you set the single value to an attribute named for that value’s data type. You then specify the Collection that you want to search in the values attribute.
Alternatively, you can construct a complex operator that compares some portion of the two items. To do this, define a subclass of java.util.Comparator that identifies the characteristics to compare.
To find an EJB in a Collection of EJBs, use dsp:containsEJB.
Example
<dsp:tomap bean="Math101Students" var="students"/>
<dsp:tomap bean="Profile" var="profile"/>
<dsp:contains var="enrolled" values="${students}" object="${profile.getId}"/>
<c:choose>
<c:when test="${enrolled}">
Welcome, <c:out value="${profile.firstName}"/>. You're
enrolled in Math 101!
</c:when>
</c:choose>In this example, if the specified user profile ID matches one of the IDs in students, the user’s first name is retrieved and the specified message displays.
