Cannot save ArrayList of Uri in a file: NotSerializableException

Question

I must save an ArrayList of Ury so I use the code

public static void saveUriList(ArrayList<Uri> myUriList) {
        if (storageAvailable()) {
            try {
                FileOutputStream uriListSaved = new FileOutputStream(
                        baseDir + File.separator + filename);
                ObjectOutputStream uriList = new ObjectOutputStream(
                        uriListSaved);
                uriList.writeObject(myUriList);
                uriList.close();
            } catch (Exception exc) {
                exc.printStackTrace(); 
            }
        }

    }

This code structure works fine for custom object that implements serializable but with Uri objects returns this Exception

10-18 21:06:40.169: W/System.err(11957): java.io.WriteAbortedException: Read an exception; java.io.NotSerializableException: android.net.Uri$StringUri
10-18 21:06:40.169: W/System.err(11957):    at java.io.ObjectInputStream.readNonPrimitiveContent(ObjectInputStream.java:933)
10-18 21:06:40.169: W/System.err(11957):    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:2262)
10-18 21:06:40.169: W/System.err(11957):    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:2217)
10-18 21:06:40.169: W/System.err(11957):    at java.util.ArrayList.readObject(ArrayList.java:665)
10-18 21:06:40.169: W/System.err(11957):    at java.lang.reflect.Method.invokeNative(Native Method)
10-18 21:06:40.169: W/System.err(11957):    at java.lang.reflect.Method.invoke(Method.java:507)
10-18 21:06:40.169: W/System.err(11957):    at java.io.ObjectInputStream.readObjectForClass(ObjectInputStream.java:1520)
10-18 21:06:40.169: W/System.err(11957):    at java.io.ObjectInputStream.readHierarchy(ObjectInputStream.java:1443)
10-18 21:06:40.169: W/System.err(11957):    at java.io.ObjectInputStream.readNewObject(ObjectInputStream.java:2112)
10-18 21:06:40.169: W/System.err(11957):    at java.io.ObjectInputStream.readNonPrimitiveContent(ObjectInputStream.java:916)
10-18 21:06:40.169: W/System.err(11957):    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:2262)
10-18 21:06:40.169: W/System.err(11957):    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:2217)
10-18 21:06:40.169: W/System.err(11957):    at it.myApp.testApp.utility.FileArchiveManager.loadUriList(FileArchiveManager.java:158)
10-18 21:06:40.169: W/System.err(11957):    at it.myApp.testApp.MyClass.onCreate(MyClass.java:107)
10-18 21:06:40.169: W/System.err(11957):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
10-18 21:06:40.169: W/System.err(11957):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1615)
10-18 21:06:40.169: W/System.err(11957):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667)
10-18 21:06:40.169: W/System.err(11957):    at android.app.ActivityThread.access$1500(ActivityThread.java:117)
10-18 21:06:40.169: W/System.err(11957):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
10-18 21:06:40.169: W/System.err(11957):    at android.os.Handler.dispatchMessage(Handler.java:99)
10-18 21:06:40.169: W/System.err(11957):    at android.os.Looper.loop(Looper.java:130)
10-18 21:06:40.169: W/System.err(11957):    at android.app.ActivityThread.main(ActivityThread.java:3687)
10-18 21:06:40.179: W/System.err(11957):    at java.lang.reflect.Method.invokeNative(Native Method)
10-18 21:06:40.179: W/System.err(11957):    at java.lang.reflect.Method.invoke(Method.java:507)
10-18 21:06:40.179: W/System.err(11957):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
10-18 21:06:40.179: W/System.err(11957):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
10-18 21:06:40.179: W/System.err(11957):    at dalvik.system.NativeStart.main(Native Method)
10-18 21:06:40.179: W/System.err(11957): Caused by: java.io.NotSerializableException: android.net.Uri$StringUri
10-18 21:06:40.179: W/System.err(11957):    at java.io.ObjectOutputStream.writeNewObject(ObjectOutputStream.java:1535)
10-18 21:06:40.179: W/System.err(11957):    at java.io.ObjectOutputStream.writeObjectInternal(ObjectOutputStream.java:1847)
10-18 21:06:40.179: W/System.err(11957):    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1689)
10-18 21:06:40.179: W/System.err(11957):    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1653)
10-18 21:06:40.179: W/System.err(11957):    at java.util.ArrayList.writeObject(ArrayList.java:651)
10-18 21:06:40.179: W/System.err(11957):    at java.lang.reflect.Method.invokeNative(Native Method)
10-18 21:06:40.179: W/System.err(11957):    at java.lang.reflect.Method.invoke(Method.java:507)
10-18 21:06:40.179: W/System.err(11957):    at java.io.ObjectOutputStream.writeHierarchy(ObjectOutputStream.java:1219)
10-18 21:06:40.179: W/System.err(11957):    at java.io.ObjectOutputStream.writeNewObject(ObjectOutputStream.java:1575)
10-18 21:06:40.179: W/System.err(11957):    at java.io.ObjectOutputStream.writeObjectInternal(ObjectOutputStream.java:1847)
10-18 21:06:40.179: W/System.err(11957):    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1689)
10-18 21:06:40.179: W/System.err(11957):    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1653)
10-18 21:06:40.179: W/System.err(11957):    at it.myApp.testApp.utility.FileArchiveManager.salvaListaPathImmagini(FileArchiveManager.java:127)
10-18 21:06:40.179: W/System.err(11957):    at it.myApp.testApp.LoadImage.onActivityResult(LoadImage.java:120)
10-18 21:06:40.179: W/System.err(11957):    at android.app.Activity.dispatchActivityResult(Activity.java:3908)
10-18 21:06:40.179: W/System.err(11957):    at android.app.ActivityThread.deliverResults(ActivityThread.java:2532)
10-18 21:06:40.179: W/System.err(11957):    at android.app.ActivityThread.handleSendResult(ActivityThread.java:2578)
10-18 21:06:40.179: W/System.err(11957):    at android.app.ActivityThread.access$2000(ActivityThread.java:117)
10-18 21:06:40.179: W/System.err(11957):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:965)
10-18 21:06:40.189: W/System.err(11957):    ... 8 more

I suppose that this happen because Uri doesn't implements Serializable....

How could I fix this problem? Must I create a custom Uri Object?

Answer 1

As you already noticed, Uri does not implement Serializable, see the reference android.net.Uri. How about storing your uris as Strings when writing your file, and converting them back to uris using Uri.parse() when reading the file?

Answer 2

when saving

String str = myUri.toString();

and when loading

Uri myUri = Uri.parse(str);