Threads, loadImageFromNetwork - Unfortunately has stopped

Question

My application does not give any compile-time error and it does show the activity like it show. It is a simple activity with a button. When the user clicks on it, it should download an image from the network. When I click on the button, it just says, "Unfortunately, Concurrency has stopped."

I am reading up on threads in android and I got to know about the rules of not performing intensive operations in the UI thread and not manipulating the UI from outside the UI thread. I was practicing this.

I am not yet familiar with how to read logcats. I am posting my logcat and it will be great if somebody can read it and point out what's causing the problem.

Moreover, the implementation of loadImageFromNetwork() is not coded by me. I just copied it from internet. So I don't have an understanding of its call to the decodeStream() method. It was not my concern for the moment.

Main.java:-

package com.example.concurrency;

import java.io.InputStream;
import java.net.URL;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.widget.ImageView;

public class MainActivity extends Activity {
    public static final String key_name="com.practice.firstApp.key";
    ImageView imageView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void downloadImage(){
        new Thread(new Runnable(){

            private Bitmap loadImageFromNetwork(String url){
                try {
                Bitmap bitmap = BitmapFactory.decodeStream((InputStream)new URL(url).getContent());
                return bitmap;
                } catch (Exception e) {
                e.printStackTrace();
                }
                return null;
                }

            public void run(){
                final Bitmap bitmap= loadImageFromNetwork("http://www.google.com/imgres?imgurl=http%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2F7%2F7a%2FBasketball.png&imgrefurl=http%3A%2F%2Fcommons.wikimedia.org%2Fwiki%2FFile%3ABasketball.png&h=340&w=340&tbnid=EJmjEDyJzrhAuM%3A&zoom=1&docid=C_hn8nOgsGmuwM&hl=en&ei=Q0o2U93LNcaIygH4mICQBQ&tbm=isch&ved=0CHwQhBwwBg&iact=rc&dur=3875&page=1&start=0&ndsp=14");
                imageView.post(new Runnable(){
                    public void run(){
                        imageView.setImageBitmap(bitmap);
                    }
                });
            }
        }).start();
    }
}

Activity_main.xml:-

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"
    android:layout_height="match_parent"

    tools:context=".MainActivity" >

     <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"

        android:text="@string/Button_MainActivity"

        android:onClick="downloadImage"/>

</RelativeLayout>

String.xml:-

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <string name="app_name">Concurrency</string>
    <string name="action_settings">Settings</string>
    <string name="hello_world">Hello world!</string>
    <string name="Button_MainActivity">Download</string>

</resources>

Manifest.xml:-

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.concurrency"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="18" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.concurrency.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Logcat:-

It exceeded the length of the question. So you can find it here.

you will use my below post definitely you will get the solution... — Naveen Kumar Kuppan, Mar 29 '14 at 14:36
I have edited my code below you will try like this it will work and one more thing Asynctask and handler is the most similar thing and handler is using to run the long time thread that's the main thing... — Naveen Kumar Kuppan, Mar 29 '14 at 17:48

Gabe Sechan · Answer 1 · 2017-12-11T14:07:13.890

0

Your downloadImage function needs to take a View as a parameter. Add that and it should fix the bug

edited Dec 11 '17 at 14:07

answered Mar 29 '14 at 14:29

Gabe Sechan

90,003
9
87
127

Naveen Kumar Kuppan · Answer 2 · 2014-03-29T17:46:44.057

You have to add this below line to get the permission to access Internet for your application...

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />

Access method of the AsynchTask function inside the activity....

    BitmapWorkerTask backPropcess = new BitmapWorkerTask(position, ht,
                        wt);
                backPropcess.executeOnExecutor(AsyncTask.SERIAL_EXECUTOR, urls);

This is a asynctask download class

            public BitmapWorkerTask() {

                }

                @Override
                protected Bitmap doInBackground(String... params) {
                                    URL url;
                        try {
                            url = new URL(params[0]);

                                HttpURLConnection connection = (HttpURLConnection) url
                                        .openConnection();
                                connection.setConnectTimeout(4000);
                                connection.setReadTimeout(10000);
                                int v = connection.getContentLength() > 0 ? connection
                                        .getContentLength() : 0;

                                    if (v > 0) {
                                        InputStream in = new BufferedInputStream(
                                                connection.getInputStream(), 32 * 1024);
                                        Bitmap bitmap = decodeSampledBitmapFromResource(
                                                in, ht[i], wt[i]);
                                        if (bitmap != null && position != null) {
                                            addBitmapToMemoryCache(position, bitmap);
                                            System.out.println(position);

                            }
                        } catch (MalformedURLException e) {
                            // e.printStackTrace();
                        } catch (IOException e) {
                            // e.printStackTrace();
                        }


                    return bitmap;
                }

                @Override
                protected void onPostExecute(Bitmap result) {
                    imageView.setImageBitmap(result);
                }
               }

Thank you for answering. 1: I'm recalling that the first line in the code to be added in the manifest file is for a permission to access the internet. Can you please tell me what the next two lines are for? — Solace, Mar 29 '14 at 15:17
I could not understand the two pieces of code you posted. Should I add the first snippet of code to my activity class? And I don't want to use Asynctask at the moment. Actually I am trying to learn concepts, so I plan to learn using Handlers and Asynctask later after this. — Solace, Mar 29 '14 at 15:21

score 0 · Answer 3 · answered Mar 29 '14 at 14:59

You can use AsyncTask or following code

private Handler mhHandler = new Handler() {
    public void handleMessage(android.os.Message msg) {
        if (msg.what == 100 && msg.obj != null) {
            imageView.setImageBitmap((Bitmap) msg.obj);
        }
    };
};

public void downloadImage(View v) {
    new Thread(new Runnable() {
        private Bitmap loadImageFromNetwork(String url) {
            try {
                Bitmap bitmap = BitmapFactory
                        .decodeStream((InputStream) new URL(url)
                                .getContent());
                return bitmap;
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }

        public void run() {
            final Bitmap bitmap = loadImageFromNetwork("http://www.google.com/imgres?imgurl=http%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2F7%2F7a%2FBasketball.png&imgrefurl=http%3A%2F%2Fcommons.wikimedia.org%2Fwiki%2FFile%3ABasketball.png&h=340&w=340&tbnid=EJmjEDyJzrhAuM%3A&zoom=1&docid=C_hn8nOgsGmuwM&hl=en&ei=Q0o2U93LNcaIygH4mICQBQ&tbm=isch&ved=0CHwQhBwwBg&iact=rc&dur=3875&page=1&start=0&ndsp=14");
            Message msg = new Message();
            msg.what = 100;
            msg.obj = bitmap;
            mhHandler.sendMessage(msg);
        }
    }).start();
}

and don't forget to put View on parameter of method downloadImage(View v) because you are calling it onClick from layout.

Actually I am learning (following [this]() tutorial), and I am just trying to learn to do this using methods like post, postDelayed, and runOnUiThread etc. Once I am clear about it, I will move on to learn the use of Handlers and Asynctasks for this purpose. — Solace, Mar 29 '14 at 15:32
not a problem just replace method downloadImage() to downloadImage(View v) that will work. — droid_ravikant, Mar 29 '14 at 15:47
I'll appreciate if you can tell me why does the downloadImage need the View v for? — Solace, Mar 29 '14 at 17:42
onClick() method having parameter View in interface View.OnClickListener thats why by calling onClick from layout needs a parameter of View . — droid_ravikant, Mar 29 '14 at 18:45

score 0 · Answer 4 · answered Nov 12 '14 at 22:00

0

Adding

<uses-permission android:name="android.permission.INTERNET" />

Also add a parameter of type "View" to your downloadImage function.

answered Nov 12 '14 at 22:00

flameshimmer

321
3
3

score 0 · Answer 5 · answered Dec 11 '17 at 12:24

private Bitmap loadImageFromNetwork(String src) {
    try {
        URL url = new URL(src);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setDoInput(true);
        connection.connect();
        InputStream input = connection.getInputStream();
        return BitmapFactory.decodeStream(input);
    } catch (IOException e) {
        Bitmap icon = BitmapFactory.decodeResource(context.getResources(), R.mipmap.ic_launcher);
        e.printStackTrace();
        return icon;
    }
}

While this code may solve the problem it would be nice to give some little explanation also. — Valerica, Dec 11 '17 at 12:48

Threads, loadImageFromNetwork - Unfortunately has stopped

5 Answers5