Question

我正在按照视频指南/教程从Treehouse制作Android自毁消息应用程序。在我从github下载了一个FileHelper类之前，事情进展顺利（由视频指南中的人员编写）。

现在当我运行应用程序并尝试通过设备的图库选择照片/视频后向后端发送消息时，它工作正常，但是当我从设备相机中选择照片/视频时崩溃，我在logcat中得到一个nullPointerException。

04-16 19:35:19.007: E/AndroidRuntime(6299): FATAL EXCEPTION: main

04-16 19:35:19.007: E/AndroidRuntime(6299): java.lang.NullPointerException

04-16 19:35:19.007: E/AndroidRuntime(6299):     at      
com.pbg.swapzy.FileHelper.getByteArrayFromFile(FileHelper.java:27)

04-16 19:35:19.007: E/AndroidRuntime(6299):     at   
com.pbg.swapzy.RecipientsActivity.createMessage(RecipientsActivity.java:159)

04-16 19:35:19.007: E/AndroidRuntime(6299):     at     
com.pbg.swapzy.RecipientsActivity.onOptionsItemSelected(RecipientsActivity.java:122)

04-16 19:35:19.007: E/AndroidRuntime(6299):     at 
android.app.Activity.onMenuItemSelected(Activity.java:2606)

04-16 19:35:19.007: E/AndroidRuntime(6299):     at 
com.android.internal.policy.impl.PhoneWindow.onMenuItemSelected(PhoneWindow.java:1045)

04-16 19:35:19.007: E/AndroidRuntime(6299):     at 
com.android.internal.view.menu.MenuBuilder.dispatchMenuItemSelected 
(MenuBuilder.java:735)

04-16 19:35:19.007: E/AndroidRuntime(6299):     at     
com.android.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:149)

04-16 19:35:19.007: E/AndroidRuntime(6299):     at 
com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:874)

04-16 19:35:19.007: E/AndroidRuntime(6299):     at 
com.android.internal.view.menu.ActionMenuView.invokeItem(ActionMenuView.java:592)

04-16 19:35:19.007: E/AndroidRuntime(6299):     at 

com.android.internal.view.menu.ActionMenuItemView.onClick(ActionMenuItemView.java:149)

04-16 19:35:19.007: E/AndroidRuntime(6299):     at 
android.view.View.performClick(View.java:4222)

04-16 19:35:19.007: E/AndroidRuntime(6299):     at     
android.view.View$PerformClick.run(View.java:17273)

04-16 19:35:19.007: E/AndroidRuntime(6299):     at 
android.os.Handler.handleCallback(Handler.java:615)

04-16 19:35:19.007: E/AndroidRuntime(6299):     at 
android.os.Handler.dispatchMessage(Handler.java:92)

04-16 19:35:19.007: E/AndroidRuntime(6299):     at 
android.os.Looper.loop(Looper.java:137)

04-16 19:35:19.007: E/AndroidRuntime(6299):     at 
android.app.ActivityThread.main(ActivityThread.java:4895)

04-16 19:35:19.007: E/AndroidRuntime(6299):     at 
java.lang.reflect.Method.invokeNative(Native Method)

04-16 19:35:19.007: E/AndroidRuntime(6299):     at 
java.lang.reflect.Method.invoke(Method.java:511)

04-16 19:35:19.007: E/AndroidRuntime(6299):     at 
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:994)

04-16 19:35:19.007: E/AndroidRuntime(6299):     at 
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:761)

04-16 19:35:19.007: E/AndroidRuntime(6299):     at 
dalvik.system.NativeStart.main(Native Method)

以下是有问题的代码

public static byte[] getByteArrayFromFile(Context context, Uri uri) {
    byte[] fileBytes = null;
    InputStream inStream = null;
    ByteArrayOutputStream outStream = null;

    if (uri.getScheme().equals("content")) {
        try {
            inStream = context.getContentResolver().openInputStream(uri);
            outStream = new ByteArrayOutputStream();

            byte[] bytesFromFile = new byte[1024*1024]; // buffer size (1 MB)
            int bytesRead = inStream.read(bytesFromFile);
            while (bytesRead != -1) {
                outStream.write(bytesFromFile, 0, bytesRead);
                bytesRead = inStream.read(bytesFromFile);
            }

            fileBytes = outStream.toByteArray();
        }
        catch (IOException e) {
            Log.e(TAG, e.getMessage());
        }
        finally {
            try {
                inStream.close();
                outStream.close();
            }
            catch (IOException e) { /*( Intentionally blank */ }
        }
    }
    else {
        try {
            File file = new File(uri.getPath());
            FileInputStream fileInput = new FileInputStream(file);
            fileBytes = IOUtils.toByteArray(fileInput);
        }
        catch (IOException e) {
            Log.e(TAG, e.getMessage());
        }
    }

    return fileBytes;
}

第27行

if (uri.getScheme().equals("content")) {

感谢您的帮助！

编辑getByteArrayFromFile用于此代码

protected ParseObject createMessage() {
    ParseObject message = new ParseObject(ParseConstants.CLASS_MESSAGES);
    message.put(ParseConstants.KEY_SENDER_ID, ParseUser.getCurrentUser().getObjectId());
    message.put(ParseConstants.KEY_SENDER_NAME, ParseUser.getCurrentUser().getUsername());
    message.put(ParseConstants.KEY_RECIPIENT_IDS, getRecipientIds());
    message.put(ParseConstants.KEY_FILE_TYPE, mFileType);

    byte[] fileBytes = FileHelper.getByteArrayFromFile(this, mMediaUri);

    if (fileBytes == null){
        return null;
    }
    else {
        if (mFileType.equals(ParseConstants.TYPE_IMAGE)) {
            fileBytes = FileHelper.reduceImageForUpload(fileBytes);
        }
        String fileName = FileHelper.getFileName(this, mMediaUri, mFileType);
        ParseFile file = new ParseFile(fileName, fileBytes);
        message.put(ParseConstants.KEY_FILE, file);

        return message;
    }
}

编辑我已经在模拟器上测试代码并且它可以正常工作，但是，它在真实设备上崩溃了。这是我的测试设备的问题吗？相机软件？该应用程序有一个minsdkversion 14，tagetsdk是19，我测试的设备是16（4.1.2）。

我完全失去了！

编辑我运行调试器并在byte[] fileBytes = FileHelper.getByteArrayFromFile(this, mMediaUri);

停止调试

一切看起来都不错，所以我让它一直运行到最后，现在一切都在设备和模拟器上完美运行。

真的很奇怪。

从github下载的FileHelper类的NullPointerException

0 个答案: