Question

我有以下AsyncTask。在onPostExecute方法中，我尝试使用Intent启动另一个活动。但是，我注意到新活动没有开始，finish()行简称为关闭当前活动。我不知道这是什么原因。

   private void uploadImage(final String city, final String offset, final int currImage, final View itemView, final Animation animation) {
    class UploadImage extends AsyncTask<String, Void, String> {
        private Context context;

        public UploadImage(Context context){
            this.context=context;
        }
      //  ProgressDialog loading;
        RequestHandler rh = new RequestHandler();

        @Override
        protected String doInBackground(String... params) {
            HashMap<String, String> data = new HashMap<>();
            data.put("city", city);
            data.put("offset",offset);
            String result = rh.sendPostRequest(SL_URL, data);

            return result;
        }

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            //loading = ProgressDialog.show(SlideShow.this, "Uploading Image", "Please wait...", true, true);
        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
           // loading.dismiss();
            JSONArray jsonArray = null;
            try {
                jsonArray = new JSONArray(s);
            } catch (JSONException e) {
                e.printStackTrace();
            }
            for (int i = 0; i < jsonArray.length(); i++) {
                try {
                    JSONObject a = jsonArray.getJSONObject(i);
                    imageDisplayerArrayList.add(new ImageDisplayer(a.getString("user_id"),a.getString("image"),a.getString("longitude"),a.getString("latitude"),a.getString("city"),a.getString("geo_name_id"),a.getString("description"),a.getString("score"),a.getString("Categories")));
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }
            itemView.clearAnimation();
            itemView.setVisibility(View.INVISIBLE);
            if (imageDisplayerArrayList.size() > 0) {
                Intent intent = new Intent(context, SlideShow.class);
                intent.putExtra("key",imageDisplayerArrayList);
                intent.putExtra("city", city);
                context.startActivity(intent);
                ((Activity) context).finish();
            }
            else {
                Toast.makeText(getApplicationContext(), "No new content available", Toast.LENGTH_LONG)
                        .show();                }



        }}
    UploadImage ui = new UploadImage(this);
    ui.execute(city);


}

PARCELABLE IMAGEDISPLAYER CLASS：

public class ImageDisplayer implements Parcelable {
private String user_id;
private String image;
private String longitude;

private ImageDisplayer(Parcel in) {
    this.user_id = in.readString();
    this.image = in.readString();
    this.longitude = in.readString();
    this.latitude = in.readString();
    this.city = in.readString();
    this.geo_name_id = in.readString();
    this.description = in.readString();
    this.score = in.readString();
    this.categories = in.readString();
}
public ImageDisplayer(String user_id, String image, String longitude, String latitude, String city, String geo_name_id, String description, String score, String categories) {
    this.user_id = user_id;
    this.image = image;
    this.longitude = longitude;
    this.latitude = latitude;
    this.city = city;
    this.geo_name_id = geo_name_id;
    this.description = description;
    this.score = score;
    this.categories = categories;
}

public String getUser_id() {

    return user_id;
}

public void setUser_id(String user_id) {
    this.user_id = user_id;
}

public String getImage() {
    return image;
}

public void setImage(String image) {
    this.image = image;
}

public String getLongitude() {
    return longitude;
}

public void setLongitude(String longitude) {
    this.longitude = longitude;
}

public String getLatitude() {
    return latitude;
}

public void setLatitude(String latitude) {
    this.latitude = latitude;
}

public String getCity() {
    return city;
}

public void setCity(String city) {
    this.city = city;
}

public String getGeo_name_id() {
    return geo_name_id;
}

public void setGeo_name_id(String geo_name_id) {
    this.geo_name_id = geo_name_id;
}

public String getDescription() {
    return description;
}

public void setDescription(String description) {
    this.description = description;
}

public String getScore() {
    return score;
}

public void setScore(String score) {
    this.score = score;
}

public String getCategories() {
    return categories;
}

public void setCategories(String categories) {
    this.categories = categories;
}

private String latitude;
private String city;
private String geo_name_id;
private String description;
private String score;
private String categories;

@Override
public int describeContents() {
    return 0;
}

@Override
public void writeToParcel(Parcel dest, int flags) {
    dest.writeString(user_id);
    dest.writeString(image);
    dest.writeString(longitude);
    dest.writeString(latitude);
    dest.writeString(city);
    dest.writeString(geo_name_id);
    dest.writeString(description);
    dest.writeString(score);
    dest.writeString(categories);

}
public static final Parcelable.Creator<ImageDisplayer> CREATOR
        = new Parcelable.Creator<ImageDisplayer>() {

    // This simply calls our new constructor (typically private) and
    // passes along the unmarshalled `Parcel`, and then returns the new object!
    @Override
    public ImageDisplayer createFromParcel(Parcel in) {
        return new ImageDisplayer(in);
    }

    // We just need to copy this and change the type to match our class.
    @Override
    public ImageDisplayer[] newArray(int size) {
        return new ImageDisplayer[size];
    }
};

}

SLIDESHOW

public class SlideShow extends Activity {

private ArrayList<ImageDisplayer> imageDisplayerArrayList = new ArrayList<>();
private String city;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_slide_show);
    imageDisplayerArrayList = getIntent().getParcelableExtra("key");
    TextView time_rem = (TextView) findViewById(R.id.time_rem);
    time_rem.bringToFront();
    city = getIntent().getStringExtra("city");
    slideshow(imageDisplayerArrayList, 0, 0);
}


private void uploadImage2(final String city, final String offset, final int currImage) {
    class UploadImage extends AsyncTask<String, Void, String> {

        //ProgressDialog loading;
        RequestHandler rh = new RequestHandler();

        @Override
        protected String doInBackground(String... params) {
            HashMap<String, String> data = new HashMap<>();
            data.put("city", city);
            data.put("offset",offset);
            String result = rh.sendPostRequest(SL_URL, data);

            return result;
        }

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
           // loading = ProgressDialog.show(SlideShow.this, "Uploading Image", "Please wait...", true, true);
        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
          //  loading.dismiss();
            JSONArray jsonArray = null;
            try {
                jsonArray = new JSONArray(s);
            } catch (JSONException e) {
                e.printStackTrace();
            }
            for (int i = 0; i < jsonArray.length(); i++) {
                try {
                    JSONObject a = jsonArray.getJSONObject(i);
                    imageDisplayerArrayList.add(new ImageDisplayer(a.getString("user_id"),a.getString("image"),a.getString("longitude"),a.getString("latitude"),a.getString("city"),a.getString("geo_name_id"),a.getString("description"),a.getString("score"),a.getString("Categories")));
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }


        }}
    UploadImage ui = new UploadImage();
    ui.execute(city);


}

public Bitmap ConvertToImage(String image){
        byte[] decodedByte = Base64.decode(image, 0);
        return BitmapFactory.decodeByteArray(decodedByte, 0, decodedByte.length);
    }

public void slideshow(ArrayList<ImageDisplayer> a, final int currImage, final int offset) {
    ImageView imageView = (ImageView) findViewById(R.id.picturedisplay);
    int currphoto = 0;

    final long DELAY = 300; // milliseconds
    final long VIEW_TIME = 10000;
    Timer timer = new Timer();
    final TimerTask update_time = new TimerTask() {
        @Override
        public void run() {
            SlideShow.this.runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    TextView time_rem = (TextView) findViewById(R.id.time_rem);
                    int timeRem = Integer.parseInt(time_rem.getText().toString());
                    timeRem--;
                    time_rem.setText(Integer.toString(timeRem));
                }});
        }};
    timer.scheduleAtFixedRate(
            new TimerTask() {
                int i = currImage;
                int off = 0;
                @Override
                public void run() {
                    SlideShow.this.runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            if (i < imageDisplayerArrayList.size()) {
                                TextView time_rem = (TextView) findViewById(R.id.time_rem);
                                time_rem.setText("10");
                                Bitmap myBitmap = ConvertToImage(imageDisplayerArrayList.get(i).getImage());
                                ImageView imageView = (ImageView) findViewById(R.id.picturedisplay);
                                imageView.setImageBitmap(myBitmap);
                                imageView.setScaleType(ImageView.ScaleType.FIT_XY);
                                Toast.makeText(getApplicationContext(),
                                Integer.toString(imageDisplayerArrayList.size()), Toast.LENGTH_LONG)
                               .show();
                                i++;
                                off = (int)(Math.rint(Math.ceil((double) i / 10) * 10));
                                if (i % 5 == 0 && i % 10 != 0) {
                                    uploadImage2(city,Integer.toString(off),i);
                                }
                            }
                            else {
                                update_time.cancel();
                                Intent i = new Intent(SlideShow.this,ViewScreen.class);
                                startActivity(i);
                                finish();
                            }
                                                                  }});
                }


            },
            DELAY,VIEW_TIME
    );
    timer.scheduleAtFixedRate(update_time, 0, 1000);

}

}

更新

这是由于我的图像arraylist超过1MB限制而导致以下错误FAILED BINDER TRANSACTION !!!。有人可以帮我创建一个替代解决方案，让这个arraylist在这两个活动之间传递吗？

Answer 1

首先，你必须获取ParcelableArrayList imagesArrayList = getIntent().getParcelableArrayListExtra("key");

其次，您在slide show函数中执行了太多的I / O工作，导致延迟

第三您正在使用位图工作并在Ui Thread上显示位图，您必须使用通用图像加载器https://github.com/nostra13/Android-Universal-Image-Loader <移动您的位图工作离开ui线程/ p>

希望这有帮助。

Answer 2

查看此代码。当你调用asynctask传递活动上下文时就是它。

Intent intent = new Intent(((Activity) context), SlideShow.class);
intent.putParcelableArrayListExtra("key",imageDisplayerArrayList);
intent.putExtra("city", city);
((Activity) context).startActivity(intent);
((Activity) context).finish();

现在您在另一个活动中检索您的数组列表

imageDisplayerArrayList = getIntent（）。getParcelableArrayListExtra（“key”）;

如果您在列表中传递位图，请不要这样做，只需在其中传递url。

Answer 3

使用createSocketPair创建一对ParcelFileDescriptor，并通过将对象放入intent中将其中一个对象传递给活动。然后，您可以通过从parcel文件描述符的基础File[Input|Output]Stream object创建FileDescriptor来传递数据。（使用getFileDescriptor()获取FileDescriptor）

来自AsyncTask startActivity的意图不起作用（FAILED BINDER TRANSACTION）

3 个答案: