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Added in API level 1

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

DexFile

public final class DexFile
extends Object

java.lang.Object
↳	dalvik.system.DexFile

Manipulates DEX files. The class is similar in principle to ZipFile. It is used primarily by class loaders.

Note we don't directly open and read the DEX file here. They're memory-mapped read-only by the VM.

Summary

Public constructors
`DexFile(File file)` Opens a DEX file from a given File object.
`DexFile(String fileName)` Opens a DEX file from a given filename.

Public methods
`void`	`close()` Closes the DEX file.
`Enumeration<String>`	`entries()` Enumerate the names of the classes in this DEX file.
`String`	`getName()` Gets the name of the (already opened) DEX file.
`static boolean`	`isDexOptNeeded(String fileName)` Returns true if the VM believes that the apk/jar file is out of date and should be passed through "dexopt" again.
`Class`	`loadClass(String name, ClassLoader loader)` Loads a class.
`static DexFile`	`loadDex(String sourcePathName, String outputPathName, int flags)` Open a DEX file, specifying the file in which the optimized DEX data should be written.
`String`	`toString()` Returns a string representation of the object.

Protected methods
`void`	`finalize()` Called when the class is finalized.

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

DexFile

Added in API level 1

DexFile (File file)

Opens a DEX file from a given File object. This will usually be a ZIP/JAR file with a "classes.dex" inside. The VM will generate the name of the corresponding file in /data/dalvik-cache and open it, possibly creating or updating it first if system permissions allow. Don't pass in the name of a file in /data/dalvik-cache, as the named file is expected to be in its original (pre-dexopt) state.

Parameters
`file`	`File`: the File object referencing the actual DEX file

Throws
`IOException`	if an I/O error occurs, such as the file not being found or access rights missing for opening it

DexFile

Added in API level 1

DexFile (String fileName)

Opens a DEX file from a given filename. This will usually be a ZIP/JAR file with a "classes.dex" inside. The VM will generate the name of the corresponding file in /data/dalvik-cache and open it, possibly creating or updating it first if system permissions allow. Don't pass in the name of a file in /data/dalvik-cache, as the named file is expected to be in its original (pre-dexopt) state.

Parameters
`fileName`	`String`: the filename of the DEX file

Throws
`IOException`	if an I/O error occurs, such as the file not being found or access rights missing for opening it

Public methods

close

Added in API level 1

void close ()

Closes the DEX file.

This may not be able to release all of the resources. If classes from this DEX file are still resident, the DEX file can't be unmapped. In the case where we do not release all the resources, close is called again in the finalizer.

Throws
`IOException`	if an I/O error occurs during closing the file, which normally should not happen

entries

Added in API level 1

Enumeration<String> entries ()

Enumerate the names of the classes in this DEX file.

Returns
`Enumeration<String>`	an enumeration of names of classes contained in the DEX file, in the usual internal form (like "java/lang/String").

getName

Added in API level 1

String getName ()

Gets the name of the (already opened) DEX file.

Returns
`String`	the file name

isDexOptNeeded

Added in API level 1

boolean isDexOptNeeded (String fileName)

Returns true if the VM believes that the apk/jar file is out of date and should be passed through "dexopt" again.

Parameters
`fileName`	`String`: the absolute path to the apk/jar file to examine.

Returns
`boolean`	true if dexopt should be called on the file, false otherwise.

Throws
`FileNotFoundException`	if fileName is not readable, not a file, or not present.
`IOException`	if fileName is not a valid apk/jar file or if problems occur while parsing it.
`NullPointerException`	if fileName is null.

loadClass

Added in API level 1

Class loadClass (String name, 
                ClassLoader loader)

Loads a class. Returns the class on success, or a null reference on failure.

If you are not calling this from a class loader, this is most likely not going to do what you want. Use forName(String) instead.

The method does not throw ClassNotFoundException if the class isn't found because it isn't reasonable to throw exceptions wildly every time a class is not found in the first DEX file we look at.

Parameters
`name`	`String`: the class name, which should look like "java/lang/String"
`loader`	`ClassLoader`: the class loader that tries to load the class (in most cases the caller of the method

Returns
`Class`	the `Class` object representing the class, or `null` if the class cannot be loaded

loadDex

Added in API level 3

DexFile loadDex (String sourcePathName, 
                String outputPathName, 
                int flags)

Open a DEX file, specifying the file in which the optimized DEX data should be written. If the optimized form exists and appears to be current, it will be used; if not, the VM will attempt to regenerate it. This is intended for use by applications that wish to download and execute DEX files outside the usual application installation mechanism. This function should not be called directly by an application; instead, use a class loader such as dalvik.system.DexClassLoader.

Parameters
`sourcePathName`	`String`: Jar or APK file with "classes.dex". (May expand this to include "raw DEX" in the future.)
`outputPathName`	`String`: File that will hold the optimized form of the DEX data.
`flags`	`int`: Enable optional features. (Currently none defined.)

Returns
`DexFile`	A new or previously-opened DexFile.

Throws
`IOException`	If unable to open the source or output file.

toString

Added in API level 1

String toString ()

Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.

The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:

 getClass().getName() + '@' + Integer.toHexString(hashCode())

Returns
`String`	a string representation of the object.

Protected methods

finalize

Added in API level 1

void finalize ()

Called when the class is finalized. Makes sure the DEX file is closed.

Throws
`IOException`	if an I/O error occurs during closing the file, which normally should not happen
`Throwable`