Method (Java Debug Interface )
Keywords: com.sun.jdi.Method interface
Date: 2018-03-02

com.sun.jdi

## Interface Method

- All Superinterfaces:
    Accessible, Comparable<Method>, Locatable, Mirror, TypeComponent

      @Exported
      public interface Method
      extends TypeComponent, Locatable, Comparable<Method>

  A static or instance method in the target VM. See `TypeComponent` for general information about Field and Method mirrors.
  Since:
    1.3
  See Also:
    `ObjectReference`, `ReferenceType`

- - ### Method Summary

    All Methods Instance Methods Abstract Methods Default Methods
    Modifier and Type | Method and Description
    --- | ---
    `List<Location>` | `allLineLocations()` Returns a list containing a `Location` object for each executable source line in this method.
    `List<Location>` | `allLineLocations(String stratum, String sourceName)` Returns a list containing a `Location` object for each executable source line in this method.
    `List<LocalVariable>` | `arguments()` Returns a list containing each `LocalVariable` that is declared as an argument of this method.
    `List<String>` | `argumentTypeNames()` Returns a list containing a text representation of the type of each formal parameter of this method.
    `List<Type>` | `argumentTypes()` Returns a list containing the type of each formal parameter of this method.
    `byte[]` | `bytecodes()` Returns an array containing the bytecodes for this method.
    `boolean` | `equals(Object obj)` Compares the specified Object with this method for equality.
    `int` | `hashCode()` Returns the hash code value for this Method.
    `boolean` | `isAbstract()` Determine if this method is abstract.
    `boolean` | `isBridge()` Determine if this method is a bridge method.
    `boolean` | `isConstructor()` Determine if this method is a constructor.
    `default boolean` | `isDefault()` Determine if this method is a default method
    `boolean` | `isNative()` Determine if this method is native.
    `boolean` | `isObsolete()` Determine if this method is obsolete.
    `boolean` | `isStaticInitializer()` Determine if this method is a static initializer.
    `boolean` | `isSynchronized()` Determine if this method is synchronized.
    `boolean` | `isVarArgs()` Determine if this method accepts a variable number of arguments.
    `Location` | `location()` Returns the `Location` of this method, if there is executable code associated with it.
    `Location` | `locationOfCodeIndex(long codeIndex)` Returns a `Location` for the given code index.
    `List<Location>` | `locationsOfLine(int lineNumber)` Returns a List containing all `Location` objects that map to the given line number.
    `List<Location>` | `locationsOfLine(String stratum, String sourceName, int lineNumber)` Returns a List containing all `Location` objects that map to the given line number and source name.
    `Type` | `returnType()` Returns the return type, as specified in the declaration of this method.
    `String` | `returnTypeName()` Returns a text representation of the return type, as specified in the declaration of this method.
    `List<LocalVariable>` | `variables()` Returns a list containing each `LocalVariable` declared in this method.
    `List<LocalVariable>` | `variablesByName(String name)` Returns a list containing each `LocalVariable` of a given name in this method.

    - ### Methods inherited from interface com.sun.jdi.TypeComponent

      `declaringType, genericSignature, isFinal, isStatic, isSynthetic, name, signature`

    - ### Methods inherited from interface com.sun.jdi.Mirror

      `toString, virtualMachine`

    - ### Methods inherited from interface com.sun.jdi.Accessible

      `isPackagePrivate, isPrivate, isProtected, isPublic, modifiers`

    - ### Methods inherited from interface java.lang.Comparable

      `compareTo`

- - ### Method Detail

    - #### returnTypeName

          String returnTypeName()

      Returns a text representation of the return type, as specified in the declaration of this method.

      This type name is always available even if the type has not yet been created or loaded.

      Returns:
        a String containing the return type name.

    - #### returnType

          Type returnType()
                   throws ClassNotLoadedException

      Returns the return type, as specified in the declaration of this method.

      Note: if the return type of this method is a reference type (class, interface, or array) and it has not been created or loaded by the declaring type's class loader - that is, ``declaringType()`` `.classLoader()`, then ClassNotLoadedException will be thrown. Also, a reference type may have been loaded but not yet prepared, in which case the type will be returned but attempts to perform some operations on the returned type (e.g. `fields()`) will throw a `ClassNotPreparedException`. Use `ReferenceType.isPrepared()` to determine if a reference type is prepared.

      Returns:
        the return `Type` of this method.
      Throws:
        `ClassNotLoadedException` - if the type has not yet been created or loaded through the appropriate class loader.
      See Also:
        `Type`, `Field.type() - for usage examples`

    - #### argumentTypeNames

          List<String> argumentTypeNames()

      Returns a list containing a text representation of the type of each formal parameter of this method.

      This list is always available even if the types have not yet been created or loaded.

      Returns:
        a `List` of `String`, one List element for each parameter of this method. Each element represents the type of a formal parameter as specified at compile-time. If the formal parameter was declared with an ellipsis, then it is represented as an array of the type before the ellipsis.

    - #### argumentTypes

          List<Type> argumentTypes()
                            throws ClassNotLoadedException

      Returns a list containing the type of each formal parameter of this method.

      Note: if there is any parameter whose type is a reference type (class, interface, or array) and it has not been created or loaded by the declaring type's class loader - that is, ``declaringType()`` `.classLoader()`, then ClassNotLoadedException will be thrown. Also, a reference type may have been loaded but not yet prepared, in which case the list will be returned but attempts to perform some operations on the type (e.g. `fields()`) will throw a `ClassNotPreparedException`. Use `ReferenceType.isPrepared()` to determine if a reference type is prepared.

      Returns:
        return a `List` of `Type`, one List element for each parameter of this method. Each element represents the type of a formal parameter as specified at compile-time. If the formal parameter was declared with an ellipsis, then it is represented as an array of the type before the ellipsis.
      Throws:
        `ClassNotLoadedException` - if the type has not yet been loaded through the appropriate class loader.
      See Also:
        `Type`

    - #### isAbstract

          boolean isAbstract()

      Determine if this method is abstract.
      Returns:
        `true` if the method is declared abstract; false otherwise.

    - #### isDefault

          default boolean isDefault()

      Determine if this method is a default method
      Returns:
        `true` if the method is declared default; false otherwise
      Since:
        1.8

    - #### isSynchronized

          boolean isSynchronized()

      Determine if this method is synchronized.
      Returns:
        `true` if the method is declared synchronized; false otherwise.

    - #### isNative

          boolean isNative()

      Determine if this method is native.
      Returns:
        `true` if the method is declared native; false otherwise.

    - #### isVarArgs

          boolean isVarArgs()

      Determine if this method accepts a variable number of arguments.
      Returns:
        `true` if the method accepts a variable number of arguments, false otherwise.
      Since:
        1.5

    - #### isBridge

          boolean isBridge()

      Determine if this method is a bridge method. Bridge methods are defined in The Java™ Language Specification.
      Returns:
        `true` if the method is a bridge method, false otherwise.
      Since:
        1.5

    - #### isConstructor

          boolean isConstructor()

      Determine if this method is a constructor.
      Returns:
        `true` if the method is a constructor; false otherwise.

    - #### isStaticInitializer

          boolean isStaticInitializer()

      Determine if this method is a static initializer.
      Returns:
        `true` if the method is a static initializer; false otherwise.

    - #### isObsolete

          boolean isObsolete()

      Determine if this method is obsolete.
      Returns:
        `true` if this method has been made obsolete by a `VirtualMachine.redefineClasses(java.util.Map<? extends com.sun.jdi.ReferenceType, byte[]>)` operation.
      Since:
        1.4

    - #### allLineLocations

          List<Location> allLineLocations()
                                   throws AbsentInformationException

      Returns a list containing a `Location` object for each executable source line in this method.

      This method is equivalent to `allLineLocations(vm.getDefaultStratum(),null)` - see `allLineLocations(String,String)` for more information.

      Returns:
        a List of all source line `Location` objects.
      Throws:
        `AbsentInformationException` - if there is no line number information for this (non-native, non-abstract) method.

    - #### allLineLocations

          List<Location> allLineLocations(String stratum,
                                          String sourceName)
                                   throws AbsentInformationException

      Returns a list containing a `Location` object for each executable source line in this method.

      Each location maps a source line to a range of code indices. The beginning of the range can be determined through `Location.codeIndex()`. The returned list is ordered by code index (from low to high).

      The returned list may contain multiple locations for a particular line number, if the compiler and/or VM has mapped that line to two or more disjoint code index ranges.

      If the method is native or abstract, an empty list is returned.

      Returned list is for the specified stratum (see `Location` for a description of strata).

      Parameters:
        `stratum` - The stratum to retrieve information from or `null` for the `ReferenceType.defaultStratum()`
        `sourceName` - Return locations only within this source file or `null` to return locations.
      Returns:
        a List of all source line `Location` objects.
      Throws:
        `AbsentInformationException` - if there is no line number information for this (non-native, non-abstract) method. Or if sourceName is non-`null` and source name information is not present.
      Since:
        1.4

    - #### locationsOfLine

          List<Location> locationsOfLine(int lineNumber)
                                  throws AbsentInformationException

      Returns a List containing all `Location` objects that map to the given line number.

      This method is equivalent to `locationsOfLine(vm.getDefaultStratum(), null, lineNumber)` - see `locationsOfLine(java.lang.String,java.lang.String,int)` for more information.

      Parameters:
        `lineNumber` - the line number
      Returns:
        a List of `Location` objects that map to the given line number.
      Throws:
        `AbsentInformationException` - if there is no line number information for this method.

    - #### locationsOfLine

          List<Location> locationsOfLine(String stratum,
                                         String sourceName,
                                         int lineNumber)
                                  throws AbsentInformationException

      Returns a List containing all `Location` objects that map to the given line number and source name.

      Returns a list containing each `Location` that maps to the given line. The returned list will contain a location for each disjoint range of code indices that have been assigned to the given line by the compiler and/or VM. Each returned location corresponds to the beginning of this range. An empty list will be returned if there is no executable code at the specified line number; specifically, native and abstract methods will always return an empty list.

      Returned list is for the specified stratum (see `Location` for a description of strata).

      Parameters:
        `stratum` - the stratum to use for comparing line number and source name, or null to use the default stratum
        `sourceName` - the source name containing the line number, or null to match all source names
        `lineNumber` - the line number
      Returns:
        a List of `Location` objects that map to the given line number.
      Throws:
        `AbsentInformationException` - if there is no line number information for this method. Or if sourceName is non-`null` and source name information is not present.
      Since:
        1.4

    - #### locationOfCodeIndex

          Location locationOfCodeIndex(long codeIndex)

      Returns a `Location` for the given code index.
      Returns:
        the `Location` corresponding to the given code index or null if the specified code index is not a valid code index for this method (native and abstract methods will always return null).

    - #### variables

          List<LocalVariable> variables()
                                 throws AbsentInformationException

      Returns a list containing each `LocalVariable` declared in this method. The list includes any variable declared in any scope within the method. It may contain multiple variables of the same name declared within disjoint scopes. Arguments are considered local variables and will be present in the returned list. If local variable information is not available, values of actual arguments to method invocations can be obtained by using the method `StackFrame.getArgumentValues()`
      Returns:
        the list of `LocalVariable` objects which mirror local variables declared in this method in the target VM. If there are no local variables, a zero-length list is returned.
      Throws:
        `AbsentInformationException` - if there is no variable information for this method. Generally, local variable information is not available for native or abstract methods (that is, their argument name information is not available), thus they will throw this exception.

    - #### variablesByName

          List<LocalVariable> variablesByName(String name)
                                       throws AbsentInformationException

      Returns a list containing each `LocalVariable` of a given name in this method. Multiple variables can be returned if the same variable name is used in disjoint scopes within the method.
      Returns:
        the list of `LocalVariable` objects of the given name. If there are no matching local variables, a zero-length list is returned.
      Throws:
        `AbsentInformationException` - if there is no variable information for this method. Generally, local variable information is not available for native or abstract methods (that is, their argument name information is not available), thus they will throw this exception.

    - #### arguments

          List<LocalVariable> arguments()
                                 throws AbsentInformationException

      Returns a list containing each `LocalVariable` that is declared as an argument of this method. If local variable information is not available, values of actual arguments to method invocations can be obtained by using the method `StackFrame.getArgumentValues()`
      Returns:
        the list of `LocalVariable` arguments. If there are no arguments, a zero-length list is returned.
      Throws:
        `AbsentInformationException` - if there is no variable information for this method. Generally, local variable information is not available for native or abstract methods (that is, their argument name information is not available), thus they will throw this exception.

    - #### bytecodes

          byte[] bytecodes()

      Returns an array containing the bytecodes for this method.

      Not all target virtual machines support this operation. Use `VirtualMachine.canGetBytecodes()` to determine if the operation is supported.

      Returns:
        the array of bytecodes; abstract and native methods will return a zero-length array.
      Throws:
        `UnsupportedOperationException` - if the target virtual machine does not support the retrieval of bytecodes.

    - #### location

          Location location()

      Returns the `Location` of this method, if there is executable code associated with it.
      Specified by:
        `location` in interface `Locatable`
      Returns:
        the `Location` of this mirror, or null if this is an abstract method; native methods will return a Location object whose codeIndex is -1.

    - #### equals

          boolean equals(Object obj)

      Compares the specified Object with this method for equality.
      Overrides:
        `equals` in class `Object`
      Parameters:
        `obj` - the reference object with which to compare.
      Returns:
        true if the Object is a method and if both mirror the same method (declared in the same class or interface, in the same VM).
      See Also:
        `Object.hashCode()`, `HashMap`

    - #### hashCode

          int hashCode()

      Returns the hash code value for this Method.
      Overrides:
        `hashCode` in class `Object`
      Returns:
        the integer hash code
      See Also:
        `Object.equals(java.lang.Object)`, `System.identityHashCode(java.lang.Object)`

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