OutOfMemory Error while reading files to byte[]

Question

I am trying to read video files in a byte[] and then encrypt them. The files which are relatively large i.e. more than 30 mb are giving out of memory exception. Here is the code I am using to read the file to byte[]:

FileInputStream fin=new FileInputStream(file);
byte[] fileContent = new byte[(int)file.length()];
fin.read(fileContent);

This is the error I am getting:

05-17 05:54:59.356: E/AndroidRuntime(4082): FATAL EXCEPTION: main
05-17 05:54:59.356: E/AndroidRuntime(4082): java.lang.OutOfMemoryError
05-17 05:54:59.356: E/AndroidRuntime(4082):     at com.vencrypto.ExplorerActivity$3.onItemClick(ExplorerActivity.java:136)
05-17 05:54:59.356: E/AndroidRuntime(4082):     at android.widget.AdapterView.performItemClick(AdapterView.java:298)
05-17 05:54:59.356: E/AndroidRuntime(4082):     at android.widget.AbsListView.performItemClick(AbsListView.java:1100)
05-17 05:54:59.356: E/AndroidRuntime(4082):     at android.widget.AbsListView$PerformClick.run(AbsListView.java:2788)
05-17 05:54:59.356: E/AndroidRuntime(4082):     at android.widget.AbsListView$1.run(AbsListView.java:3463)
05-17 05:54:59.356: E/AndroidRuntime(4082):     at android.os.Handler.handleCallback(Handler.java:730)
05-17 05:54:59.356: E/AndroidRuntime(4082):     at android.os.Handler.dispatchMessage(Handler.java:92)
05-17 05:54:59.356: E/AndroidRuntime(4082):     at android.os.Looper.loop(Looper.java:137)
05-17 05:54:59.356: E/AndroidRuntime(4082):     at android.app.ActivityThread.main(ActivityThread.java:5103)
05-17 05:54:59.356: E/AndroidRuntime(4082):     at java.lang.reflect.Method.invokeNative(Native Method)
05-17 05:54:59.356: E/AndroidRuntime(4082):     at java.lang.reflect.Method.invoke(Method.java:525)
05-17 05:54:59.356: E/AndroidRuntime(4082):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
05-17 05:54:59.356: E/AndroidRuntime(4082):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
05-17 05:54:59.356: E/AndroidRuntime(4082):     at dalvik.system.NativeStart.main(Native Method)

I know the files are too large but there must be a way right.

Instead of trying to allocate an array the size of the file, allocate an array of a manageable size, e.g. 2MB and use a loop that processes the file one chunk at a time, writing the chunks to a file output stream as you go along. — Barend
– Barend, Commented May 17, 2014 at 10:18

the6p4c · Accepted Answer · 2014-05-17 10:18:29Z

1

Instead of using a FileInputStream directly, wrap that in a BufferedInputStream, so that you don't allocate huge amounts of memory. A buffered input stream reads the data in segments, so you can encrypt that piece, and, if you are writing it back to a file, use a BufferedWriter to write that file in the same way.

answered May 17, 2014 at 10:18

the6p4c

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3 Comments

William Price Over a year ago

The important part is to not try to fit it all into a byte[] at once. Work on smaller portions of the file at a time, or do all of your operations using the input/output streams themselves.

Sourabh Over a year ago

can you please elaborate the method a little. I guess I need to create the byte array for that too, the error is on the line where I am creating the byte[].

the6p4c Over a year ago

@Sourabh No, you don't need to create a byte array. Create a BufferedInputStream by using a new BufferedInputStream(new FileInputStream()) (with the parameters that you've used). Have a look a the BufferedInputStream JavaDoc. Inside the BufferedInputStream, it reads the data in small segments, which is how you should process your data, instead of one huge byte[].

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