Package jakarta.servlet.jsp.jstl.core

Class ConditionalTagSupport

java.lang.Object
jakarta.servlet.jsp.tagext.TagSupport
jakarta.servlet.jsp.jstl.core.ConditionalTagSupport
All Implemented Interfaces:
jakarta.servlet.jsp.tagext.IterationTag, jakarta.servlet.jsp.tagext.JspTag, jakarta.servlet.jsp.tagext.Tag, Serializable
public abstract class ConditionalTagSupport
extends jakarta.servlet.jsp.tagext.TagSupport

Abstract class that facilitates implementation of conditional actions where the boolean result is exposed as a JSP scoped variable. The boolean result may then be used as the test condition in a <c:when> action.

This base class provides support for:

  • Conditional processing of the action's body based on the returned value of the abstract method condition().
  • Storing the result of condition() as a Boolean object into a JSP scoped variable identified by attributes var and scope.
Author:
Shawn Bayern
See Also:
Serialized Form

  • Field Summary

    Fields inherited from class jakarta.servlet.jsp.tagext.TagSupport

    id, pageContext

    Fields inherited from interface jakarta.servlet.jsp.tagext.IterationTag

    EVAL_BODY_AGAIN

    Fields inherited from interface jakarta.servlet.jsp.tagext.Tag

    EVAL_BODY_INCLUDE, EVAL_PAGE, SKIP_BODY, SKIP_PAGE

  • Constructor Summary

    Constructors
    Constructor Description
    ConditionalTagSupport()
    Base constructor to initialize local state.

  • Method Summary

    Modifier and Type Method Description
    protected abstract boolean condition()
    Subclasses implement this method to compute the boolean result of the conditional action.
    int doStartTag()
    Includes its body if condition() evaluates to true.
    void release()
    Releases any resources this ConditionalTagSupport may have (or inherit).
    void setScope​(String scope)
    Sets the 'scope' attribute.
    void setVar​(String var)
    Sets the 'var' attribute.

    Methods inherited from class jakarta.servlet.jsp.tagext.TagSupport

    doAfterBody, doEndTag, findAncestorWithClass, getId, getParent, getValue, getValues, removeValue, setId, setPageContext, setParent, setValue

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • ConditionalTagSupport

      public ConditionalTagSupport()
      Base constructor to initialize local state. As with TagSupport, subclasses should not implement constructors with arguments, and no-argument constructors implemented by subclasses must call the superclass constructor.

  • Method Details

    • condition

      protected abstract boolean condition() throws jakarta.servlet.jsp.JspTagException

      Subclasses implement this method to compute the boolean result of the conditional action. This method is invoked once per tag invocation by doStartTag().

      Returns:
      a boolean representing the condition that a particular subclass uses to drive its conditional logic.
      Throws:
      jakarta.servlet.jsp.JspTagException

    • doStartTag

      public int doStartTag() throws jakarta.servlet.jsp.JspException
      Includes its body if condition() evaluates to true.
      Specified by:
      doStartTag in interface jakarta.servlet.jsp.tagext.Tag
      Overrides:
      doStartTag in class jakarta.servlet.jsp.tagext.TagSupport
      Throws:
      jakarta.servlet.jsp.JspException

    • release

      public void release()
      Releases any resources this ConditionalTagSupport may have (or inherit).
      Specified by:
      release in interface jakarta.servlet.jsp.tagext.Tag
      Overrides:
      release in class jakarta.servlet.jsp.tagext.TagSupport

    • setVar

      public void setVar​(String var)
      Sets the 'var' attribute.
      Parameters:
      var - Name of the exported scoped variable storing the result of condition().

    • setScope

      public void setScope​(String scope)
      Sets the 'scope' attribute.
      Parameters:
      scope - Scope of the 'var' attribute