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Java compact3 javax.lang.model.util Class ElementScanner6<R,P>（JDK8）

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Java™ Platform
Standard Ed. 8
compact3
javax.lang.model.util

Class ElementScanner6<R,P>

  • Type Parameters:
    R - the return type of this visitor's methods. Use Void for visitors that do not need to return results.
    P - the type of the additional parameter to this visitor's methods. Use Void for visitors that do not need an additional parameter.
    All Implemented Interfaces:
    ElementVisitor<R,P>
    Direct Known Subclasses:
    ElementScanner7 

    @SupportedSourceVersion(value=RELEASE_6)
public class ElementScanner6<R,P>
extends AbstractElementVisitor6<R,P>
    A scanning visitor of program elements with default behavior appropriate for the RELEASE_6 source version. The visitXYZ methods in this class scan their component elements by calling scan on their enclosed elements, parameters, etc., as indicated in the individual method specifications. A subclass can control the order elements are visited by overriding the visitXYZ methods. Note that clients of a scanner may get the desired behavior be invoking v.scan(e, p) rather than v.visit(e, p) on the root objects of interest.

    When a subclass overrides a visitXYZ method, the new method can cause the enclosed elements to be scanned in the default way by calling super.visitXYZ. In this fashion, the concrete visitor can control the ordering of traversal over the component elements with respect to the additional processing; for example, consistently calling super.visitXYZ at the start of the overridden methods will yield a preorder traversal, etc. If the component elements should be traversed in some other order, instead of calling super.visitXYZ, an overriding visit method should call scan with the elements in the desired order.

    Methods in this class may be overridden subject to their general contract. Note that annotating methods in concrete subclasses with @Override will help ensure that methods are overridden as intended.

    WARNING: The ElementVisitor interface implemented by this class may have methods added to it in the future to accommodate new, currently unknown, language structures added to future versions of the Java™ programming language. Therefore, methods whose names begin with "visit" may be added to this class in the future; to avoid incompatibilities, classes which extend this class should not declare any instance methods with names beginning with "visit".

    When such a new visit method is added, the default implementation in this class will be to call the visitUnknown method. A new element scanner visitor class will also be introduced to correspond to the new language level; this visitor will have different default behavior for the visit method in question. When the new visitor is introduced, all or portions of this visitor may be deprecated.

    Since:
    1.6
    See Also:
    ElementScanner7, ElementScanner8

    • Field Detail

      • DEFAULT_VALUE

        protected final R DEFAULT_VALUE
        The specified default value.

    • Constructor Detail

      • ElementScanner6

        protected ElementScanner6()
        Constructor for concrete subclasses; uses null for the default value.

      • ElementScanner6

        protected ElementScanner6(R defaultValue)
        Constructor for concrete subclasses; uses the argument for the default value.
        Parameters:
        defaultValue - the default value

    • Method Detail

      • scan

        public final R scan(Iterable<? extends Element> iterable,
                    P p)
        Iterates over the given elements and calls scan(Element, P) on each one. Returns the result of the last call to scan or DEFAULT_VALUE for an empty iterable.
        Parameters:
        iterable - the elements to scan
        p - additional parameter
        Returns:
        the scan of the last element or DEFAULT_VALUE if no elements

      • scan

        public R scan(Element e,
              P p)
        Processes an element by calling e.accept(this, p); this method may be overridden by subclasses.
        Parameters:
        e - the element to scan
        p - a scanner-specified parameter
        Returns:
        the result of visiting e.

      • scan

        public final R scan(Element e)
        Convenience method equivalent to v.scan(e, null).
        Parameters:
        e - the element to scan
        Returns:
        the result of scanning e.

      • visitPackage

        public R visitPackage(PackageElement e,
                      P p)
        Visits a package element. This implementation scans the enclosed elements.
        Parameters:
        e - the element to visit
        p - a visitor-specified parameter
        Returns:
        the result of scanning

      • visitType

        public R visitType(TypeElement e,
                   P p)
        Visits a type element. This implementation scans the enclosed elements.
        Parameters:
        e - the element to visit
        p - a visitor-specified parameter
        Returns:
        the result of scanning

      • visitVariable

        public R visitVariable(VariableElement e,
                       P p)
        Visits a variable element. This implementation scans the enclosed elements, unless the element is a RESOURCE_VARIABLE in which case visitUnknown is called.
        Parameters:
        e - the element to visit
        p - a visitor-specified parameter
        Returns:
        the result of scanning

      • visitExecutable

        public R visitExecutable(ExecutableElement e,
                         P p)
        Visits an executable element. This implementation scans the parameters.
        Parameters:
        e - the element to visit
        p - a visitor-specified parameter
        Returns:
        the result of scanning

      • visitTypeParameter

        public R visitTypeParameter(TypeParameterElement e,
                            P p)
        Visits a type parameter element. This implementation scans the enclosed elements.
        Parameters:
        e - the element to visit
        p - a visitor-specified parameter
        Returns:
        the result of scanning
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Java™ Platform
Standard Ed. 8

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