Package com.sun.jna

Class Memory

java.lang.Object
com.sun.jna.Pointer
com.sun.jna.Memory
All Implemented Interfaces:
Closeable, AutoCloseable
Direct Known Subclasses:
StringArray
public class Memory extends Pointer implements Closeable
A Pointer to memory obtained from the native heap via a call to malloc.

In some cases it might be necessary to use memory obtained from malloc. For example, Memory helps accomplish the following idiom: 

        void *buf = malloc(BUF_LEN * sizeof(char));
        call_some_function(buf);
        free(buf);
Author:
Sheng Liang, originator, Todd Fast, suitability modifications, Timothy Wall
See Also:

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected long
    size
     

    Fields inherited from class com.sun.jna.Pointer

    NULL, peer

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    protected
    Memory()
     
     
    Memory(long size)
    Allocate space in the native heap via a call to C's malloc.

  • Method Summary

    Modifier and Type
    Method
    Description
    Memory
    align(int byteBoundary)
    Provide a view onto this structure with the given alignment.
    protected void
    boundsCheck(long off, long sz)
    Check that indirection won't cause us to write outside the malloc'ed space.
    void
    clear()
    Zero the full extent of this memory region.
    void
    close()
    Free the native memory and set peer to zero
    protected void
    dispose()
    Deprecated.
    static void
    disposeAll()
    Dispose of all allocated memory.
    String
    dump()
    Dumps the contents of this memory object.
    protected static void
    free(long p)
     
    byte
    getByte(long offset)
    Indirect the native pointer to malloc space, a la Pointer.getByte.
    ByteBuffer
    getByteBuffer(long offset, long length)
    Get a ByteBuffer mapped to a portion of this memory.
    char
    getChar(long offset)
    Indirect the native pointer to malloc space, a la Pointer.getByte.
    double
    getDouble(long offset)
    Indirect the native pointer to malloc space, a la Pointer.getDouble.
    float
    getFloat(long offset)
    Indirect the native pointer to malloc space, a la Pointer.getFloat.
    int
    getInt(long offset)
    Indirect the native pointer to malloc space, a la Pointer.getInt.
    long
    getLong(long offset)
    Indirect the native pointer to malloc space, a la Pointer.getLong.
    Pointer
    getPointer(long offset)
    Indirect the native pointer to malloc space, a la Pointer.getPointer.
    short
    getShort(long offset)
    Indirect the native pointer to malloc space, a la Pointer.getShort.
    String
    getString(long offset, String encoding)
    Copy native memory to a Java String using the requested encoding.
    String
    getWideString(long offset)
    Read a wide (const wchar_t *) string from memory.
    protected static long
    malloc(long size)
     
    static void
    purge()
    Force cleanup of memory that has associated NIO Buffers which have been GC'd.
    void
    read(long bOff, byte[] buf, int index, int length)
    Indirect the native pointer to malloc space, a la Pointer.read.
    void
    read(long bOff, char[] buf, int index, int length)
    Indirect the native pointer to malloc space, a la Pointer.read.
    void
    read(long bOff, double[] buf, int index, int length)
    Indirect the native pointer to malloc space, a la Pointer.read.
    void
    read(long bOff, float[] buf, int index, int length)
    Indirect the native pointer to malloc space, a la Pointer.read.
    void
    read(long bOff, int[] buf, int index, int length)
    Indirect the native pointer to malloc space, a la Pointer.read.
    void
    read(long bOff, long[] buf, int index, int length)
    Indirect the native pointer to malloc space, a la Pointer.read.
    void
    read(long bOff, short[] buf, int index, int length)
    Indirect the native pointer to malloc space, a la Pointer.read.
    void
    read(long bOff, Pointer[] buf, int index, int length)
    Indirect the native pointer to malloc space, a la Pointer.read.
    void
    setByte(long offset, byte value)
    Indirect the native pointer to malloc space, a la Pointer.setByte.
    void
    setChar(long offset, char value)
    Indirect the native pointer to malloc space, a la Pointer.setChar.
    void
    setDouble(long offset, double value)
    Indirect the native pointer to malloc space, a la Pointer.setDouble.
    void
    setFloat(long offset, float value)
    Indirect the native pointer to malloc space, a la Pointer.setFloat.
    void
    setInt(long offset, int value)
    Indirect the native pointer to malloc space, a la Pointer.setInt.
    void
    setLong(long offset, long value)
    Indirect the native pointer to malloc space, a la Pointer.setLong.
    void
    setPointer(long offset, Pointer value)
    Indirect the native pointer to malloc space, a la Pointer.setPointer.
    void
    setShort(long offset, short value)
    Indirect the native pointer to malloc space, a la Pointer.setShort.
    void
    setString(long offset, String value, String encoding)
    Copy string value to the location being pointed to, using the requested encoding.
    void
    setWideString(long offset, String value)
    Copy string value to the location being pointed to as a wide string (wchar_t*).
    Pointer
    share(long offset)
    Provide a view of this memory using the given offset as the base address.
    Pointer
    share(long offset, long sz)
    Provide a view of this memory using the given offset as the base address, bounds-limited with the given size.
    long
    size()
     
    String
    toString()
     
    boolean
    valid()
    Returns false if the memory has been freed.
    void
    write(long bOff, byte[] buf, int index, int length)
    Indirect the native pointer to malloc space, a la Pointer.write.
    void
    write(long bOff, char[] buf, int index, int length)
    Indirect the native pointer to malloc space, a la Pointer.write.
    void
    write(long bOff, double[] buf, int index, int length)
    Indirect the native pointer to malloc space, a la Pointer.write.
    void
    write(long bOff, float[] buf, int index, int length)
    Indirect the native pointer to malloc space, a la Pointer.write.
    void
    write(long bOff, int[] buf, int index, int length)
    Indirect the native pointer to malloc space, a la Pointer.write.
    void
    write(long bOff, long[] buf, int index, int length)
    Indirect the native pointer to malloc space, a la Pointer.write.
    void
    write(long bOff, short[] buf, int index, int length)
    Indirect the native pointer to malloc space, a la Pointer.write.
    void
    write(long bOff, Pointer[] buf, int index, int length)
    Indirect the native pointer to malloc space, a la Pointer.write.

    Methods inherited from class com.sun.jna.Pointer

    clear, createConstant, createConstant, dump, equals, getByteArray, getCharArray, getDoubleArray, getFloatArray, getIntArray, getLongArray, getNativeLong, getPointerArray, getPointerArray, getShortArray, getString, getStringArray, getStringArray, getStringArray, getStringArray, getValue, getWideStringArray, getWideStringArray, hashCode, indexOf, nativeValue, nativeValue, setMemory, setNativeLong, setString, setString, setValue

    Methods inherited from class java.lang.Object

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

  • Field Details

    • size

      protected long size

  • Constructor Details

    • Memory

      public Memory(long size)
      Allocate space in the native heap via a call to C's malloc.
      Parameters:
      size - number of bytes of space to allocate

    • Memory

      protected Memory()

  • Method Details

    • purge

      public static void purge()
      Force cleanup of memory that has associated NIO Buffers which have been GC'd.

    • disposeAll

      public static void disposeAll()
      Dispose of all allocated memory.

    • share

      public Pointer share(long offset)
      Provide a view of this memory using the given offset as the base address. The returned Pointer will have a size equal to that of the original minus the offset.
      Overrides:
      share in class Pointer
      Throws:
      IndexOutOfBoundsException - if the requested memory is outside the allocated bounds.

    • share

      public Pointer share(long offset, long sz)
      Provide a view of this memory using the given offset as the base address, bounds-limited with the given size. Maintains a reference to the original Memory object to avoid GC as long as the shared memory is referenced.
      Overrides:
      share in class Pointer
      Throws:
      IndexOutOfBoundsException - if the requested memory is outside the allocated bounds.

    • align

      public Memory align(int byteBoundary)
      Provide a view onto this structure with the given alignment.
      Parameters:
      byteBoundary - Align memory to this number of bytes; should be a power of two.
      Throws:
      IndexOutOfBoundsException - if the requested alignment can not be met.
      IllegalArgumentException - if the requested alignment is not a positive power of two.

    • close

      public void close()
      Free the native memory and set peer to zero
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable

    • dispose

      @Deprecated protected void dispose()
      Deprecated.

    • clear

      public void clear()
      Zero the full extent of this memory region.

    • valid

      public boolean valid()
      Returns false if the memory has been freed.

    • size

      public long size()

    • boundsCheck

      protected void boundsCheck(long off, long sz)
      Check that indirection won't cause us to write outside the malloc'ed space.

    • read

      public void read(long bOff, byte[] buf, int index, int length)
      Indirect the native pointer to malloc space, a la Pointer.read. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      read in class Pointer
      Parameters:
      bOff - byte offset from pointer from which data is copied
      buf - byte array into which data is copied
      index - array index to which data is copied
      length - number of elements from native pointer that must be copied
      See Also:

    • read

      public void read(long bOff, short[] buf, int index, int length)
      Indirect the native pointer to malloc space, a la Pointer.read. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      read in class Pointer
      Parameters:
      bOff - byte offset from pointer from which data is copied
      buf - short array into which data is copied
      index - array index to which data is copied
      length - number of elements from native pointer that must be copied
      See Also:

    • read

      public void read(long bOff, char[] buf, int index, int length)
      Indirect the native pointer to malloc space, a la Pointer.read. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      read in class Pointer
      Parameters:
      bOff - byte offset from pointer from which data is copied
      buf - char array into which data is copied
      index - array index to which data is copied
      length - number of elements from native pointer that must be copied
      See Also:

    • read

      public void read(long bOff, int[] buf, int index, int length)
      Indirect the native pointer to malloc space, a la Pointer.read. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      read in class Pointer
      Parameters:
      bOff - byte offset from pointer from which data is copied
      buf - int array into which data is copied
      index - array index to which data is copied
      length - number of elements from native pointer that must be copied
      See Also:

    • read

      public void read(long bOff, long[] buf, int index, int length)
      Indirect the native pointer to malloc space, a la Pointer.read. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      read in class Pointer
      Parameters:
      bOff - byte offset from pointer from which data is copied
      buf - long array into which data is copied
      index - array index to which data is copied
      length - number of elements from native pointer that must be copied
      See Also:

    • read

      public void read(long bOff, float[] buf, int index, int length)
      Indirect the native pointer to malloc space, a la Pointer.read. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      read in class Pointer
      Parameters:
      bOff - byte offset from pointer from which data is copied
      buf - float array into which data is copied
      index - array index to which data is copied
      length - number of elements from native pointer that must be copied
      See Also:

    • read

      public void read(long bOff, double[] buf, int index, int length)
      Indirect the native pointer to malloc space, a la Pointer.read. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      read in class Pointer
      Parameters:
      bOff - byte offset from pointer from which data is copied
      buf - double array into which data is copied
      index - array index to which data is copied
      length - number of elements from native pointer that must be copied
      See Also:

    • read

      public void read(long bOff, Pointer[] buf, int index, int length)
      Indirect the native pointer to malloc space, a la Pointer.read. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      read in class Pointer
      Parameters:
      bOff - byte offset from pointer from which data is copied
      buf - Pointer array into which data is copied
      index - array index to which data is copied
      length - number of elements from native pointer that must be copied
      See Also:

    • write

      public void write(long bOff, byte[] buf, int index, int length)
      Indirect the native pointer to malloc space, a la Pointer.write. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      write in class Pointer
      Parameters:
      bOff - byte offset from pointer into which data is copied
      buf - byte array from which to copy
      index - array index from which to start copying
      length - number of elements from buf that must be copied
      See Also:

    • write

      public void write(long bOff, short[] buf, int index, int length)
      Indirect the native pointer to malloc space, a la Pointer.write. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      write in class Pointer
      Parameters:
      bOff - byte offset from pointer into which data is copied
      buf - short array from which to copy
      index - array index from which to start copying
      length - number of elements from buf that must be copied
      See Also:

    • write

      public void write(long bOff, char[] buf, int index, int length)
      Indirect the native pointer to malloc space, a la Pointer.write. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      write in class Pointer
      Parameters:
      bOff - byte offset from pointer into which data is copied
      buf - char array from which to copy
      index - array index from which to start copying
      length - number of elements from buf that must be copied
      See Also:

    • write

      public void write(long bOff, int[] buf, int index, int length)
      Indirect the native pointer to malloc space, a la Pointer.write. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      write in class Pointer
      Parameters:
      bOff - byte offset from pointer into which data is copied
      buf - int array from which to copy
      index - array index from which to start copying
      length - number of elements from buf that must be copied
      See Also:

    • write

      public void write(long bOff, long[] buf, int index, int length)
      Indirect the native pointer to malloc space, a la Pointer.write. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      write in class Pointer
      Parameters:
      bOff - byte offset from pointer into which data is copied
      buf - long array from which to copy
      index - array index from which to start copying
      length - number of elements from buf that must be copied
      See Also:

    • write

      public void write(long bOff, float[] buf, int index, int length)
      Indirect the native pointer to malloc space, a la Pointer.write. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      write in class Pointer
      Parameters:
      bOff - byte offset from pointer into which data is copied
      buf - float array from which to copy
      index - array index from which to start copying
      length - number of elements from buf that must be copied
      See Also:

    • write

      public void write(long bOff, double[] buf, int index, int length)
      Indirect the native pointer to malloc space, a la Pointer.write. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      write in class Pointer
      Parameters:
      bOff - byte offset from pointer into which data is copied
      buf - double array from which to copy
      index - array index from which to start copying
      length - number of elements from buf that must be copied
      See Also:

    • write

      public void write(long bOff, Pointer[] buf, int index, int length)
      Indirect the native pointer to malloc space, a la Pointer.write. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      write in class Pointer
      Parameters:
      bOff - byte offset from pointer into which data is copied
      buf - Pointer array from which to copy
      index - array index from which to start copying
      length - number of elements from buf that must be copied
      See Also:

    • getByte

      public byte getByte(long offset)
      Indirect the native pointer to malloc space, a la Pointer.getByte. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      getByte in class Pointer
      Parameters:
      offset - offset from pointer to perform the indirection
      Returns:
      the byte value being pointed to
      See Also:

    • getChar

      public char getChar(long offset)
      Indirect the native pointer to malloc space, a la Pointer.getByte. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      getChar in class Pointer
      Parameters:
      offset - offset from pointer to perform the indirection
      Returns:
      the wchar_t value being pointed to
      See Also:

    • getShort

      public short getShort(long offset)
      Indirect the native pointer to malloc space, a la Pointer.getShort. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      getShort in class Pointer
      Parameters:
      offset - byte offset from pointer to perform the indirection
      Returns:
      the short value being pointed to
      See Also:

    • getInt

      public int getInt(long offset)
      Indirect the native pointer to malloc space, a la Pointer.getInt. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      getInt in class Pointer
      Parameters:
      offset - byte offset from pointer to perform the indirection
      Returns:
      the int value being pointed to
      See Also:

    • getLong

      public long getLong(long offset)
      Indirect the native pointer to malloc space, a la Pointer.getLong. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      getLong in class Pointer
      Parameters:
      offset - byte offset from pointer to perform the indirection
      Returns:
      the long value being pointed to
      See Also:

    • getFloat

      public float getFloat(long offset)
      Indirect the native pointer to malloc space, a la Pointer.getFloat. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      getFloat in class Pointer
      Parameters:
      offset - byte offset from pointer to perform the indirection
      Returns:
      the float value being pointed to
      See Also:

    • getDouble

      public double getDouble(long offset)
      Indirect the native pointer to malloc space, a la Pointer.getDouble. But this method performs a bounds check to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      getDouble in class Pointer
      Parameters:
      offset - byte offset from pointer to perform the indirection
      Returns:
      the double value being pointed to
      See Also:

    • getPointer

      public Pointer getPointer(long offset)
      Indirect the native pointer to malloc space, a la Pointer.getPointer. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      getPointer in class Pointer
      Parameters:
      offset - byte offset from pointer to perform the indirection
      Returns:
      a Pointer equivalent of the pointer value being pointed to, or null if the pointer value is NULL;
      See Also:

    • getByteBuffer

      public ByteBuffer getByteBuffer(long offset, long length)
      Get a ByteBuffer mapped to a portion of this memory. We keep a weak reference to all ByteBuffers provided so that this memory object is not GC'd while there are still implicit outstanding references to it (it'd be nice if we could attach our own reference to the ByteBuffer, but the VM generates the object so we have no control over it).
      Overrides:
      getByteBuffer in class Pointer
      Parameters:
      offset - byte offset from pointer to start the buffer
      length - Length of ByteBuffer
      Returns:
      a direct ByteBuffer that accesses the memory being pointed to,

    • getString

      public String getString(long offset, String encoding)
      Description copied from class: Pointer
      Copy native memory to a Java String using the requested encoding.
      Overrides:
      getString in class Pointer
      Parameters:
      offset - byte offset from pointer to obtain the native string
      encoding - the desired encoding
      Returns:
      the String value being pointed to

    • getWideString

      public String getWideString(long offset)
      Description copied from class: Pointer
      Read a wide (const wchar_t *) string from memory.
      Overrides:
      getWideString in class Pointer

    • setByte

      public void setByte(long offset, byte value)
      Indirect the native pointer to malloc space, a la Pointer.setByte. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      setByte in class Pointer
      Parameters:
      offset - byte offset from pointer at which value must be set
      value - byte value to set
      See Also:

    • setChar

      public void setChar(long offset, char value)
      Indirect the native pointer to malloc space, a la Pointer.setChar. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      setChar in class Pointer
      Parameters:
      offset - byte offset from pointer at which value must be set
      value - char value to set
      See Also:

    • setShort

      public void setShort(long offset, short value)
      Indirect the native pointer to malloc space, a la Pointer.setShort. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      setShort in class Pointer
      Parameters:
      offset - byte offset from pointer at which value must be set
      value - short value to set
      See Also:

    • setInt

      public void setInt(long offset, int value)
      Indirect the native pointer to malloc space, a la Pointer.setInt. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      setInt in class Pointer
      Parameters:
      offset - byte offset from pointer at which value must be set
      value - int value to set
      See Also:

    • setLong

      public void setLong(long offset, long value)
      Indirect the native pointer to malloc space, a la Pointer.setLong. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      setLong in class Pointer
      Parameters:
      offset - byte offset from pointer at which value must be set
      value - long value to set
      See Also:

    • setFloat

      public void setFloat(long offset, float value)
      Indirect the native pointer to malloc space, a la Pointer.setFloat. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      setFloat in class Pointer
      Parameters:
      offset - byte offset from pointer at which value must be set
      value - float value to set
      See Also:

    • setDouble

      public void setDouble(long offset, double value)
      Indirect the native pointer to malloc space, a la Pointer.setDouble. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      setDouble in class Pointer
      Parameters:
      offset - byte offset from pointer at which value must be set
      value - double value to set
      See Also:

    • setPointer

      public void setPointer(long offset, Pointer value)
      Indirect the native pointer to malloc space, a la Pointer.setPointer. But this method performs a bounds checks to ensure that the indirection does not cause memory outside the malloced space to be accessed.
      Overrides:
      setPointer in class Pointer
      Parameters:
      offset - byte offset from pointer at which value must be set
      value - Pointer holding the actual pointer value to set, which may be null to indicate a NULL pointer.
      See Also:

    • setString

      public void setString(long offset, String value, String encoding)
      Description copied from class: Pointer
      Copy string value to the location being pointed to, using the requested encoding.
      Overrides:
      setString in class Pointer
      Parameters:
      offset - byte offset from pointer at which characters in value must be set
      value - java.lang.String value to set
      encoding - desired encoding

    • setWideString

      public void setWideString(long offset, String value)
      Description copied from class: Pointer
      Copy string value to the location being pointed to as a wide string (wchar_t*).
      Overrides:
      setWideString in class Pointer
      Parameters:
      offset - byte offset from pointer at which characters in value must be set
      value - java.lang.String value to set

    • toString

      public String toString()
      Overrides:
      toString in class Pointer

    • free

      protected static void free(long p)

    • malloc

      protected static long malloc(long size)

    • dump

      public String dump()
      Dumps the contents of this memory object.