Null pointer exception on rotate screen with image fields in blocks.

[Jorge gusa]

Hello:

I am usingo blockly with Android device generating blocks with JSON structure. Like this:

[
  {
    "type": "light",
    "message0": "%1 Light",
    "args0": [
      {
        "type": "field_image",
        "src": "images/led.png",
        "width": 30,
        "height": 30,
        "alt": "*"
      }
    ]
]

I have seen that the system is working properly until I have added "field_image" arguments. When I add a block and rotate the tablet I get next exception:

05-20 19:44:06.342 31683-31683/com E/AndroidRuntime: FATAL EXCEPTION: main
 Process: com, PID: 31683
 java.lang.NullPointerException: Attempt to invoke virtual method 'int com.google.blockly.model.FieldImage.getWidth()' on a null object reference
     at com.google.blockly.android.ui.fieldview.BasicFieldImageView.updateViewSize(BasicFieldImageView.java:174)
     at com.google.blockly.android.ui.fieldview.BasicFieldImageView$2.onPostExecute(BasicFieldImageView.java:141)
     at com.google.blockly.android.ui.fieldview.BasicFieldImageView$2.onPostExecute(BasicFieldImageView.java:117)
     at android.os.AsyncTask.finish(AsyncTask.java:651)
     at android.os.AsyncTask.-wrap1(AsyncTask.java)
     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:668)
     at android.os.Handler.dispatchMessage(Handler.java:102)
     at android.os.Looper.loop(Looper.java:148)
     at android.app.ActivityThread.main(ActivityThread.java:5417)
     at java.lang.reflect.Method.invoke(Native Method)
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

Could you help me?. Thank you very much.

[Andrew n marshall]

While I did find another issue (#604), was not able to recreate your described issue. I added your block definition to our DevTests activity, both with "images/led.png" present in assets/ and not, and could not reproduce your error when rotating the device (emulator). I was able to rotate it without error in both master and develop branches, on APIs 19 and 25.

Looking at the source of BasicFieldImageView, it is hard to image how the mImageField in updateViewSize() could be null for either call. That said, it shouldn't hurt to add a if (mImageField != null) around the contents of updateViewSize(), if you wanted to.

--
Andrew

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[Jorge]

Hello:

Thank you very much. There is no bug in Blockly. The problem is the way I was using Activity Lifecicle. I have put

protected void  onCreate(Bundle savedInstanceState){
 loadWorkspaceFromAppDir(fileName);
}

This is WRONG. Each time that the screens rotates it reload the file so it forces the image to unlink  "unlinkField()" that is inside "BasicFieldImageView.java" . Once the image needs to the size here you have the null pointer.

It is not necessary to reload the file each you call it. Just doing:

protected void  onCreate(Bundle savedInstanceState){
 if(savedInstanceState == null){
  loadWorkspaceFromAppDir(fileName);
 }
}

It will control if it is the first time or not you call it. Thank you very much. Please mark this error as closed due to is not a real bug.

CLOSED

Jorge

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