Module jdk.jdi
Package com.sun.jdi

Interface Location

  • All Superinterfaces:
    Comparable<Location>, Mirror
    public interface Location
extends Mirror, Comparable<Location>
    A point within the executing code of the target VM. Locations are used to identify the current position of a suspended thread (analogous to an instruction pointer or program counter register in native programs). They are also used to identify the position at which to set a breakpoint.

    The availability of a line number for a location will depend on the level of debugging information available from the target VM.

    Several mirror interfaces have locations. Each such mirror extends a Locatable interface.

    Strata

    The source information for a Location is dependent on the stratum which is used. A stratum is a source code level within a sequence of translations. For example, say the baz program is written in the programming language "Foo" then translated to the language "Bar" and finally translated into the Java programming language. The Java programming language stratum is named "Java", let's say the other strata are named "Foo" and "Bar". A given location (as viewed by the sourceName() and lineNumber() methods) might be at line 14 of "baz.foo" in the "Foo" stratum, line 23 of "baz.bar" in the "Bar" stratum and line 71 of the "Java" stratum. Note that while the Java programming language may have only one source file for a reference type, this restriction does not apply to other strata - thus each Location should be consulted to determine its source path. Queries which do not specify a stratum (sourceName(), sourcePath() and lineNumber()) use the VM's default stratum (VirtualMachine.getDefaultStratum()). If the specified stratum (whether explicitly specified by a method parameter or implicitly as the VM's default) is null or is not available in the declaring type, the declaring type's default stratum is used (declaringType().defaultStratum()). Note that in the normal case, of code that originates as Java programming language source, there will be only one stratum ("Java") and it will be returned as the default. To determine the available strata use ReferenceType.availableStrata().

    Since:
    1.3
    See Also:
    EventRequestManager, StackFrame, BreakpointEvent, ExceptionEvent, Locatable

    • Method Detail

      • declaringType

        ReferenceType declaringType()
        Gets the type to which this Location belongs. Normally the declaring type is a ClassType, but executable locations also may exist within the static initializer of an InterfaceType.
        Returns:
        the ReferenceType containing this Location.

      • method

        Method method()
        Gets the method containing this Location.
        Returns:
        the location's Method.

      • codeIndex

        long codeIndex()
        Gets the code position within this location's method.
        Returns:
        the long representing the position within the method or -1 if location is within a native method.

      • sourceName

        String sourceName​(String stratum)
           throws AbsentInformationException
        Gets an identifing name for the source corresponding to this location. Interpretation of this string is the responsibility of the source repository mechanism.

        Returned name is for the specified stratum (see the class comment for a description of strata).

        The returned string is the unqualified name of the source file for this Location. For example, java.lang.Thread would return "Thread.java".

        Parameters:
        stratum - The stratum to retrieve information from or null for the declaring type's default stratum.
        Returns:
        a string specifying the source
        Throws:
        AbsentInformationException - if the source name is not known
        Since:
        1.4

      • sourcePath

        String sourcePath​(String stratum)
           throws AbsentInformationException
        Gets the path to the source corresponding to this location. Interpretation of this string is the responsibility of the source repository mechanism.

        Returned path is for the specified stratum (see the class comment for a description of strata).

        In the reference implementation, for strata which do not explicitly specify source path (the Java programming language stratum never does), the returned string is the package name of declaringType() converted to a platform dependent path followed by the unqualified name of the source file for this Location (sourceName(stratum)). For example, on a Windows platform, java.lang.Thread would return "java\lang\Thread.java".

        Parameters:
        stratum - The stratum to retrieve information from or null for the declaring type's default stratum.
        Returns:
        a string specifying the source
        Throws:
        AbsentInformationException - if the source name is not known
        Since:
        1.4

      • lineNumber

        int lineNumber()
        Gets the line number of this Location.

        This method is equivalent to lineNumber(vm.getDefaultStratum()) - see lineNumber(String) for more information.

        Returns:
        an int specifying the line in the source, returns -1 if the information is not available; specifically, always returns -1 for native methods.

      • lineNumber

        int lineNumber​(String stratum)
        The line number of this Location. The line number is relative to the source specified by sourceName(stratum).

        Returned line number is for the specified stratum (see the class comment for a description of strata).

        Parameters:
        stratum - The stratum to retrieve information from or null for the declaring type's default stratum.
        Returns:
        an int specifying the line in the source, returns -1 if the information is not available; specifically, always returns -1 for native methods.
        Since:
        1.4

      • equals

        boolean equals​(Object obj)
        Compares the specified Object with this Location for equality.
        Overrides:
        equals in class Object
        Parameters:
        obj - the reference object with which to compare.
        Returns:
        true if the Object is a Location and if it refers to the same point in the same VM as this Location.
        See Also:
        Object.hashCode(), HashMap