Most visited

Recently visited

Results for

Added in API level 1

Summary: Ctors | Methods | Protected Methods | Inherited Methods | [Expand All]

MemoryFile

public class MemoryFile
extends Object

java.lang.Object
↳	android.os.MemoryFile

MemoryFile is a wrapper for the Linux ashmem driver. MemoryFiles are backed by shared memory, which can be optionally set to be purgeable. Purgeable files may have their contents reclaimed by the kernel in low memory conditions (only if allowPurging is set to true). After a file is purged, attempts to read or write the file will cause an IOException to be thrown.

Summary

Public constructors
`MemoryFile(String name, int length)` Allocates a new ashmem region.

Public methods
`boolean`	`allowPurging(boolean allowPurging)` Enables or disables purging of the memory file.
`void`	`close()` Closes the memory file.
`InputStream`	`getInputStream()` Creates a new InputStream for reading from the memory file.
`OutputStream`	`getOutputStream()` Creates a new OutputStream for writing to the memory file.
`boolean`	`isPurgingAllowed()` Is memory file purging enabled?
`int`	`length()` Returns the length of the memory file.
`int`	`readBytes(byte[] buffer, int srcOffset, int destOffset, int count)` Reads bytes from the memory file.
`void`	`writeBytes(byte[] buffer, int srcOffset, int destOffset, int count)` Write bytes to the memory file.

Protected methods
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.

Inherited methods

From class java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long millis, int nanos)` Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed.
`final void`	`wait(long millis)` Causes the current thread to wait until either another thread invokes the `notify()` method or the `notifyAll()` method for this object, or a specified amount of time has elapsed.
`final void`	`wait()` Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object.

Public constructors

MemoryFile

Added in API level 1

MemoryFile (String name, 
                int length)

Allocates a new ashmem region. The region is initially not purgable.

Parameters
`name`	`String`: optional name for the file (can be null).
`length`	`int`: of the memory file in bytes, must be non-negative.

Throws
`IOException`	if the memory file could not be created.

Public methods

allowPurging

Added in API level 1

boolean allowPurging (boolean allowPurging)

Enables or disables purging of the memory file.

Parameters
`allowPurging`	`boolean`: true if the operating system can purge the contents of the file in low memory situations

Returns
`boolean`	previous value of allowPurging

Throws
`IOException`

close

Added in API level 1

void close ()

Closes the memory file. If there are no other open references to the memory file, it will be deleted.

getInputStream

Added in API level 1

InputStream getInputStream ()

Creates a new InputStream for reading from the memory file.

Returns
`InputStream`	InputStream

getOutputStream

Added in API level 1

OutputStream getOutputStream ()

Creates a new OutputStream for writing to the memory file.

Returns
`OutputStream`	OutputStream

isPurgingAllowed

Added in API level 1

boolean isPurgingAllowed ()

Is memory file purging enabled?

Returns
`boolean`	true if the file may be purged.

length

Added in API level 1

int length ()

Returns the length of the memory file.

Returns
`int`	file length.

readBytes

Added in API level 1

int readBytes (byte[] buffer, 
                int srcOffset, 
                int destOffset, 
                int count)

Reads bytes from the memory file. Will throw an IOException if the file has been purged.

Parameters
`buffer`	`byte`: byte array to read bytes into.
`srcOffset`	`int`: offset into the memory file to read from.
`destOffset`	`int`: offset into the byte array buffer to read into.
`count`	`int`: number of bytes to read.

Returns
`int`	number of bytes read.

Throws
`IOException`	if the memory file has been purged or deactivated.

writeBytes

Added in API level 1

void writeBytes (byte[] buffer, 
                int srcOffset, 
                int destOffset, 
                int count)

Write bytes to the memory file. Will throw an IOException if the file has been purged.

Parameters
`buffer`	`byte`: byte array to write bytes from.
`srcOffset`	`int`: offset into the byte array buffer to write from.
`destOffset`	`int`: offset into the memory file to write to.
`count`	`int`: number of bytes to write.

Throws
`IOException`	if the memory file has been purged or deactivated.

Protected methods

finalize

Added in API level 1

void finalize ()

Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. A subclass overrides the finalize method to dispose of system resources or to perform other cleanup.

The general contract of finalize is that it is invoked if and when the Java^TM virtual machine has determined that there is no longer any means by which this object can be accessed by any thread that has not yet died, except as a result of an action taken by the finalization of some other object or class which is ready to be finalized. The finalize method may take any action, including making this object available again to other threads; the usual purpose of finalize, however, is to perform cleanup actions before the object is irrevocably discarded. For example, the finalize method for an object that represents an input/output connection might perform explicit I/O transactions to break the connection before the object is permanently discarded.

The finalize method of class Object performs no special action; it simply returns normally. Subclasses of Object may override this definition.

The Java programming language does not guarantee which thread will invoke the finalize method for any given object. It is guaranteed, however, that the thread that invokes finalize will not be holding any user-visible synchronization locks when finalize is invoked. If an uncaught exception is thrown by the finalize method, the exception is ignored and finalization of that object terminates.

After the finalize method has been invoked for an object, no further action is taken until the Java virtual machine has again determined that there is no longer any means by which this object can be accessed by any thread that has not yet died, including possible actions by other objects or classes which are ready to be finalized, at which point the object may be discarded.

The finalize method is never invoked more than once by a Java virtual machine for any given object.

Any exception thrown by the finalize method causes the finalization of this object to be halted, but is otherwise ignored.