Java Debug Interface

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 Summary
 long codeIndex()
          Gets the code position within this location's method.
 ReferenceType declaringType()
          Gets the type to which this Location belongs.
 boolean equals(Object obj)
          Compares the specified Object with this Location for equality.
 int hashCode()
          Returns the hash code value for this Location.
 int lineNumber()
          Gets the line number of this Location.
 int lineNumber(String stratum)
          The line number of this Location.
 Method method()
          Gets the method containing this Location.
 String sourceName()
          Gets an identifing name for the source corresponding to this location.
 String sourceName(String stratum)
          Gets an identifing name for the source corresponding to this location.
 String sourcePath()
          Gets the path to the source corresponding to this location.
 String sourcePath(String stratum)
          Gets the path to the source corresponding to this location.
 
Methods inherited from interface com.sun.jdi.Mirror
toString, virtualMachine
 
Methods inherited from interface java.lang.Comparable
compareTo
 

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()
                  throws AbsentInformationException
Gets an identifing name for the source corresponding to this location.

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

Returns:
a string specifying the source
Throws:
AbsentInformationException - if the source name is not known

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()
                  throws AbsentInformationException
Gets the path to the source corresponding to this location.

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

Returns:
a string specifying the source
Throws:
AbsentInformationException - if the source name is not known

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
Returns:
true if the Object is a Location and if it refers to the same point in the same VM as this Location.

hashCode

int hashCode()
Returns the hash code value for this Location.

Overrides:
hashCode in class Object
Returns:
the integer hash code

Java Debug Interface

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