Load something from Internet using URLConnection and BufferedReader, in AsyncTask

Here is example to load something from Internet using URLConnection and BufferedReader, in AsyncTask.

MainActivity.java

package com.blogspot.android_er.androidinternet;

import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;
import android.widget.Toast;

import org.w3c.dom.Text;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;

public class MainActivity extends AppCompatActivity {

    TextView textResult;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textResult = (TextView)findViewById(R.id.tresult);

        MyAsyncTask myAsyncTask = new MyAsyncTask(textResult);
        myAsyncTask.execute("http://android-er.blogspot.com");
    }

    class MyAsyncTask extends AsyncTask<String, Void, String> {

        TextView textviewResult;

        public MyAsyncTask(TextView textviewResult) {
            super();
            this.textviewResult = textviewResult;
        }

        @Override
        protected String doInBackground(String... params) {
            String result = "";

            try {
                URL url = new URL(params[0]);
                URLConnection urlConnection = url.openConnection();
                InputStream inputStream = urlConnection.getInputStream();
                InputStreamReader inputStreamReader =
                        new InputStreamReader(inputStream);
                BufferedReader buffReader = new BufferedReader(inputStreamReader);

                String line;
                while ((line = buffReader.readLine()) != null) {
                    result += line;
                }

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

            return result;
        }

        @Override
        protected void onPostExecute(String s) {
            textviewResult.setText(s);

            Toast.makeText(MainActivity.this,
                    "DONE", Toast.LENGTH_LONG).show();
            super.onPostExecute(s);
        }
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:orientation="vertical"
    android:padding="16dp"
    tools:context="com.blogspot.android_er.androidinternet.MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://android-er.blogspot.com/"
        android:textStyle="bold" />

    <ScrollView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">
    <TextView
        android:id="@+id/tresult"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    </ScrollView>
</LinearLayout>

uses-permission of "android.permission.INTERNET" is needed in src/main/AndroidManifest.xml.

---

Add uses-permission of "android.permission.INTERNET" to AndroidManifest.xml

To access Internet in your app, you have to add uses-permission of "android.permission.INTERNET" to AndroidManifest.xml. Shown in this video:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.blogspot.android_er.androidinternet">

    <uses-permission android:name="android.permission.INTERNET"/>
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

</manifest>

Related:
- Load something from Internet using URLConnection and BufferedReader, in Thread

AsyncTask vs Thread + Handler

This post show how to implement using AsyncTask and Thread/Handler to perform the same function: doing something in background and update UI elements (ProgressBar and TextView).

This video show how it run on Android Emulator running Android N, in Multi-Window.

---

AsyncTask

MainActivity.java

package com.blogspot.android_er.androidasynctask;

import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    Button btnStart;
    ProgressBar progressBar;
    TextView textMsg;

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

        progressBar = (ProgressBar)findViewById(R.id.progress);
        textMsg = (TextView)findViewById(R.id.msg);

        btnStart = (Button)findViewById(R.id.start);
        btnStart.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                MyAsyncTask myAsyncTask = new MyAsyncTask(progressBar, textMsg);
                myAsyncTask.execute();
            }
        });
    }

    class MyAsyncTask extends AsyncTask<Void, Integer, Void>{

        ProgressBar pBar;
        TextView tMsg;

        public MyAsyncTask(ProgressBar pBar, TextView tMsg) {
            super();
            this.pBar = pBar;
            this.tMsg = tMsg;
        }

        @Override
        protected Void doInBackground(Void... params) {
            for(int i=0; i<=10; i++){
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

                publishProgress(i);
            }
            return null;
        }

        @Override
        protected void onProgressUpdate(Integer... values) {
            pBar.setProgress(values[0]);
        }

        @Override
        protected void onPostExecute(Void aVoid) {
            tMsg.setText("finished");
        }
    }
}

layout/activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:padding="16dp"
    android:orientation="vertical"
    tools:context="com.blogspot.android_er.androidasynctask.MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://android-er.blogspot.com/"
        android:textStyle="bold" />

    <Button
        android:id="@+id/start"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Start"/>

    <ProgressBar
        android:id="@+id/progress"
        style="?android:attr/progressBarStyleHorizontal"
        android:indeterminate="false"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:max="10"
        android:progress="0"/>
    <TextView
        android:id="@+id/msg"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
</LinearLayout>

---

Thread + Handler

MainActivity.java

package com.blogspot.android_er.androidthreadhandler;

import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;

import org.w3c.dom.Text;

public class MainActivity extends AppCompatActivity {

    Button btnStart;
    ProgressBar progressBar;
    TextView textMsg;

    private Handler handler = new Handler();

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

        progressBar = (ProgressBar)findViewById(R.id.progress);
        textMsg = (TextView)findViewById(R.id.msg);

        btnStart = (Button)findViewById(R.id.start);
        btnStart.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                MyThread myThread = new MyThread(progressBar, textMsg);
                myThread.start();
            }
        });
    }

    class MyThread extends Thread{

        ProgressBar pBar;
        TextView tMsg;

        public MyThread(ProgressBar pBar, TextView tMsg) {
            super();
            this.pBar = pBar;
            this.tMsg = tMsg;
        }

        @Override
        public void run() {

            for (int i = 0; i <= 10; i++) {
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

                //is accessed from within inner class, needs to be declared final
                final int finalI = i;
                handler.post(new Runnable() {
                    @Override
                    public void run() {
                        pBar.setProgress(finalI);
                    }
                });
            }

            handler.post(new Runnable() {
                @Override
                public void run() {
                    tMsg.setText("finished");
                }
            });
        }
    }
}

layout/activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:padding="16dp"
    android:orientation="vertical"
    tools:context="com.blogspot.android_er.androidthreadhandler.MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://android-er.blogspot.com/"
        android:textStyle="bold" />

    <Button
        android:id="@+id/start"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Start"/>

    <ProgressBar
        android:id="@+id/progress"
        style="?android:attr/progressBarStyleHorizontal"
        android:indeterminate="false"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:max="10"
        android:progress="0"/>
    <TextView
        android:id="@+id/msg"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
</LinearLayout>

---

next:
- HandlerThread example

related:
- Load something from Internet using URLConnection and BufferedReader, in AsyncTask
- Load something from Internet using URLConnection and BufferedReader, in Thread

Too busy in background thread of AsyncTask

It's a following of the post "ProgressDialog and AsyncTask". I make the background process of the AsyncTask too busy by removing the Thread.sleep() inside doInBackground(). In such case, the system is too busy to update UI, even cannot update the ProgressBar animation!



The example code refer to the post "ProgressDialog and AsyncTask".