Creating Extensions with AsyncTask (android.os.AsyncTask) possible?

[Arne Mailand]

Well is this possible or do we have to use "real" Threads?

If it is possible, how should this be done?

kind regards

[Arne Mailand]

Well, I made this:

package com.google.appinventor.components.runtime;

import com.google.appinventor.components.annotations.DesignerComponent;

import com.google.appinventor.components.annotations.DesignerProperty;

import com.google.appinventor.components.annotations.PropertyCategory;

import com.google.appinventor.components.annotations.SimpleEvent;

import com.google.appinventor.components.annotations.SimpleFunction;

import com.google.appinventor.components.annotations.SimpleObject;

import com.google.appinventor.components.annotations.SimpleProperty;

import com.google.appinventor.components.annotations.UsesPermissions;

import com.google.appinventor.components.common.ComponentCategory;

import com.google.appinventor.components.common.PropertyTypeConstants;

import com.google.appinventor.components.common.YaVersion;

import com.google.appinventor.components.runtime.util.AsynchUtil;

import com.google.appinventor.components.runtime.util.ErrorMessages;

import com.google.appinventor.components.runtime.util.FileUtil;

import com.google.appinventor.components.runtime.Form;

import com.google.appinventor.components.runtime.ReplForm;

import android.os.AsyncTask;

import android.app.Activity;

import android.content.Context;

import android.os.Environment;

import android.util.Log;

import java.io.BufferedInputStream;

import java.io.BufferedOutputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.net.Socket;

@DesignerComponent(version = YaVersion.FILE_COMPONENT_VERSION,

        description = "Meine erste Extension",

        category = ComponentCategory.EXTENSION,

        nonVisible = true,

        iconName = "images/extension.png")

@SimpleObject(external = true)

@UsesPermissions(permissionNames = "android.permission.WRITE_EXTERNAL_STORAGE, android.permission.INTERNET, android.permission.READ_EXTERNAL_STORAGE")

public class Filet extends AndroidNonvisibleComponent implements Component{

    public Filet(ComponentContainer container){

        super(container.$form());

    }

    @SimpleFunction(description = "Funktionsbeschreibung hier")

    public void Filet2(){

        new Connect().execute();

    }

    public class void Connect extends AsyncTask<Void, Void, Void>{

        protected Void doInBackground() {

        Socket socket;

        File file = new File(Environment.getExternalStorageDirectory(), "bild.jpg");

        byte[] bytes = new byte[(int) file.length()];

        try {

            socket = new Socket("192.168.178.32", 80);

            BufferedInputStream bis = new BufferedInputStream(new FileInputStream(file));

            BufferedOutputStream bos = new BufferedOutputStream(socket.getOutputStream());

            bis.read(bytes, 0, bytes.length);

            bos.write(bytes, 0, bytes.length);

            bos.flush();

            socket.close();

        } catch (FileNotFoundException e) {

            e.printStackTrace();

        } catch (IOException e) {

            e.printStackTrace();

        } finally {

//            bis.close();

//            bos.close();

        }

        }

    }

}

Compiler is telling me:

    [javac] /Users/kirikiri3/Documents/mai/appinventor/components/src/com/google/appinventor/components/runtime/Filet.java:60: error: <identifier> expected

    [javac]     public class void Connect extends AsyncTask<Void, Void, Void>{

    [javac]                 ^

    [javac] /Users/kirikiri3/Documents/mai/appinventor/components/src/com/google/appinventor/components/runtime/Filet.java:60: error: <identifier> expected

    [javac]     public class void Connect extends AsyncTask<Void, Void, Void>{

    [javac]                              ^

    [javac] /Users/kirikiri3/Documents/mai/appinventor/components/src/com/google/appinventor/components/runtime/Filet.java:60: error: <identifier> expected

    [javac]     public class void Connect extends AsyncTask<Void, Void, Void>{

    [javac]                                                                  ^

    [javac] 3 errors

When I put the inner class public class void Connect extends AsyncTask<Void, Void, Void>{} to outside, I even get more errors. So I assume, it wont work?

[Evan Patton]

The reason you are getting errors is because that is not a valid class definition. The type is class, not void, so it should be public class Connect extends AsyncTask<Void, Void, Void>.

Evan

[Jos Flores]

You should be able to use AsyncUtil as explained in the docs here:
https://docs.google.com/document/d/1xk9dMfczvjbbwD-wMsr-ffqkTlE3ga0ocCE1KOb2wvw/pub#h.8te56x1w9u8b

Using AsyncTask directly is fine, but the abstraction above seems to
be easier to use.

cheers,
José

> --
> You received this message because you are subscribed to the Google Groups
> "App Inventor Open Source Development" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to app-inventor-open-so...@googlegroups.com.
> To post to this group, send email to
> app-inventor-o...@googlegroups.com.
> Visit this group at
> https://groups.google.com/group/app-inventor-open-source-dev.
> For more options, visit https://groups.google.com/d/optout.

[Arne Mailand]

Thanks Evan, I am so dumb! I removed that void and now that line seems to be fine, but now I get this error:

    [javac] /Users/kirikiri3/Documents/mai/appinventor/components/src/com/google/appinventor/components/runtime/Filet.java:84: error: missing return statement

    [javac] }

    [javac] ^

This error is referring to one of the last lines of my code. This sounds like a noob mistake like I had many times before, but I just cant fix it. The numbers of opening and closing backets should be right. If I insert return null; here, I get the errors

    [javac] /Users/kirikiri3/Documents/mai/appinventor/components/src/com/google/appinventor/components/runtime/Filet.java:85: error: illegal start of type

    [javac] return null;}

    [javac] ^

    [javac] /Users/kirikiri3/Documents/mai/appinventor/components/src/com/google/appinventor/components/runtime/Filet.java:85: error: ';' expected

    [javac] return null;}

    [javac]       ^

    [javac] 2 errors

Any ideas how to fix this?

[Arne Mailand]

Btw when I remove null then I still get

    [javac] /Users/kirikiri3/Documents/mai/appinventor/components/src/com/google/appinventor/components/runtime/Filet.java:85: error: illegal start of type

    [javac] return;}

    [javac] ^

    [javac] 1 error

[Arne Mailand]

Yes that's the "real" threads I meant. AsyncTask would be easier since I get a code with it already, but if I dont get it working, I will switch to that option. Thanks

> email to app-inventor-open-source-dev+unsub...@googlegroups.com.

[Arne Mailand]

Well, I guess the cause of the "missing return statement" error is in this line:

        protected Void doInBackground(Void... void){

Originally, I had no parameters set, which caused errors related with overriding. With the first Void written in big letter, I get a missing-return-statement error. What I now have is this:

        protected void doInBackground(Void...){

causing only this 1 error (all other modifications will cause at least 2 errors, so I assume this should be the closest to solution?):

    [javac] /Users/kirikiri3/Documents/mai/appinventor/components/src/com/google/appinventor/components/runtime/Filet.java:63: error: <identifier> expected

    [javac]         protected void doInBackground(Void...){

    [javac]                                              ^