# Class LocalVariableInstruction

java.lang.Object
org.apache.bcel.generic.Instruction
org.apache.bcel.generic.LocalVariableInstruction

All Implemented Interfaces:
  `Cloneable, IndexedInstruction, TypedInstruction`

Direct Known Subclasses:
  `IINC, LoadInstruction, StoreInstruction`

public abstract class LocalVariableInstruction extends Instruction implements TypedInstruction, IndexedInstruction
Abstract super class for instructions dealing with local variables.

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `protected int`
  `n`
  Deprecated.
  (since 6.0) will be made private; do not access directly, use getter/setter

  ### Fields inherited from class Instruction

  `length, opcode`

- ## Constructor Summary

  Constructors
  Modifier
  Constructor
  Description
  `protected`
  `LocalVariableInstruction(short opcode, short cTag, int n)`
  Constructs a LocalVariableInstruction.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `dump(DataOutputStream out)`
  Dumps instruction as byte code to stream out.
  `short`
  `getCanonicalTag()`
  Gets the canonical tag for instruction, for example, ALOAD for ALOAD_0.
  `final int`
  `getIndex()`
  Gets the index.
  `Type`
  `getType(ConstantPoolGen cp)`
  Returns the type associated with the instruction - in case of ALOAD or ASTORE Type.OBJECT is returned.
  `protected void`
  `initFromFile(ByteSequence bytes, boolean wide)`
  Reads needed data (for example index) from file.
  `void`
  `setIndex(int n)`
  Sets the local variable index. also updates opcode and length TODO Why?
  `String`
  `toString(boolean verbose)`
  Long output format: <name of opcode> "["<opcode number>"]" "("<length of instruction>")" "<"< local variable index>">"

  ### Methods inherited from class Instruction

  `accept, consumeStack, copy, equals, getComparator, getLength, getName, getOpcode, hashCode, isValidByte, isValidShort, produceStack, readInstruction, setComparator, toString, toString`

  ### Methods inherited from class Object

  `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

- ## Field Details

  - ### n

    @Deprecated protected int n
    Deprecated.
    (since 6.0) will be made private; do not access directly, use getter/setter

- ## Constructor Details

  - ### LocalVariableInstruction

    protected LocalVariableInstruction(short opcode, short cTag, int n)
    Constructs a LocalVariableInstruction.
    Parameters:
      `opcode` - Instruction opcode.
      `cTag` - Instruction number for compact version, ALOAD_0, for example.
      `n` - local variable index (unsigned short).

- ## Method Details

  - ### dump

    public void dump(DataOutputStream out) throws IOException
    Dumps instruction as byte code to stream out.
    Overrides:
      `dump` in class `Instruction`
    Parameters:
      `out` - Output stream.
    Throws:
      `IOException` - Thrown when an I/O exception of some sort has occurred.

  - ### getCanonicalTag

    public short getCanonicalTag()
    Gets the canonical tag for instruction, for example, ALOAD for ALOAD_0.
    Returns:
      canonical tag for instruction, for example, ALOAD for ALOAD_0.

  - ### getIndex

    public final int getIndex()
    Description copied from interface: `IndexedInstruction`
    Gets the index.
    Specified by:
      `getIndex` in interface `IndexedInstruction`
    Returns:
      local variable index (n) referred by this instruction.

  - ### getType

    public Type getType(ConstantPoolGen cp)
    Returns the type associated with the instruction - in case of ALOAD or ASTORE Type.OBJECT is returned. This is just a bit incorrect, because ALOAD and ASTORE may work on every ReferenceType (including Type.NULL) and ASTORE may even work on a ReturnaddressType.
    Specified by:
      `getType` in interface `TypedInstruction`
    Parameters:
      `cp` - the constant pool generator.
    Returns:
      type associated with the instruction.

  - ### initFromFile

    protected void initFromFile(ByteSequence bytes, boolean wide) throws IOException
    Reads needed data (for example index) from file.

        (ILOAD <= tag <= ALOAD_3) || (ISTORE <= tag <= ASTORE_3)

    Overrides:
      `initFromFile` in class `Instruction`
    Parameters:
      `bytes` - byte sequence to read from.
      `wide` - "wide" instruction flag.
    Throws:
      `IOException` - may be thrown if the implementation needs to read data from the file

  - ### setIndex

    public void setIndex(int n)
    Sets the local variable index. also updates opcode and length TODO Why?
    Specified by:
      `setIndex` in interface `IndexedInstruction`
    Parameters:
      `n` - the index.
    See Also:
      - `setIndexOnly(int)`

  - ### toString

    public String toString(boolean verbose)
    Long output format: <name of opcode> "["<opcode number>"]" "("<length of instruction>")" "<"< local variable index>">"
    Overrides:
      `toString` in class `Instruction`
    Parameters:
      `verbose` - long/short format switch.
    Returns:
      mnemonic for instruction.