Nimisha Blog!: 2018

Friday, 30 November 2018

Thread Pool executor good explanation

https://www.youtube.com/watch?v=NEZ2ASoP_nY&index=4&list=PLhfHPmPYPPRl0LntrCBnQD5ln6lnqqoms

Saturday, 20 October 2018

IPC using messenger

Service Class Implementation:

https://android.googlesource.com/platform/development/+/master/samples/ApiDemos/src/com/example/android/apis/app/MessengerService.java

Activity Class Implementation:

https://android.googlesource.com/platform/development/+/master/samples/ApiDemos/src/com/example/android/apis/app/MessengerServiceActivities.java

Friday, 19 October 2018

Good site to study android

http://www.vogella.com/tutorials/android.html

Job Scheduler

1. Create Receiver:

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;

public class MyStartServiceReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        Util.scheduleJob(context);
    }
}

import android.app.job.JobInfo;
import android.app.job.JobScheduler;
import android.content.ComponentName;
import android.content.Context;

public class Util {

    // schedule the start of the service every 10 - 30 seconds
    public static void scheduleJob(Context context) {
        ComponentName serviceComponent = new ComponentName(context, TestJobService.class);
        JobInfo.Builder builder = new JobInfo.Builder(0, serviceComponent);
        builder.setMinimumLatency(1 * 1000); // wait at least
        builder.setOverrideDeadline(3 * 1000); // maximum delay
        //builder.setRequiredNetworkType(JobInfo.NETWORK_TYPE_UNMETERED); // require unmetered network
        //builder.setRequiresDeviceIdle(true); // device should be idle
        //builder.setRequiresCharging(false); // we don't care if the device is charging or not
        JobScheduler jobScheduler = context.getSystemService(JobScheduler.class);
        jobScheduler.schedule(builder.build());
    }

}

`Register the receiver in the Android manifest for the BOOT_COMPLETED event.`

<receiver android:name="MyStartServiceReceiver" >
    <intent-filter>
        <action android:name="android.intent.action.BOOT_COMPLETED" />
    </intent-filter>
</receiver>





Create JOB:

import android.app.job.JobParameters;
import android.app.job.JobService;
import android.content.Intent;

/**
 * JobService to be scheduled by the JobScheduler.
 * start another service
 */
public class TestJobService extends JobService {
    private static final String TAG = "SyncService";

    @Override
    public boolean onStartJob(JobParameters params) {
        Intent service = new Intent(getApplicationContext(), LocalWordService.class);
        getApplicationContext().startService(service);
        Util.scheduleJob(getApplicationContext()); // reschedule the job
        return true;
    }

    @Override
    public boolean onStopJob(JobParameters params) {
        return true;
    }

}

Updare Activity UI from Service once processing done-- Using Broadcast Receiver

Service Implementation:

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;

import android.app.Activity;
import android.app.IntentService;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.os.Message;
import android.os.Messenger;
import android.util.Log;

public class DownloadService extends IntentService {

    private int result = Activity.RESULT_CANCELED;
    public static final String URL = "urlpath";
    public static final String FILENAME = "filename";
    public static final String FILEPATH = "filepath";
    public static final String RESULT = "result";
    public static final String NOTIFICATION = "com.vogella.android.service.receiver";

    public DownloadService() {
        super("DownloadService");
    }

    // will be called asynchronously by Android
    @Override
    protected void onHandleIntent(Intent intent) {
        String urlPath = intent.getStringExtra(URL);
        String fileName = intent.getStringExtra(FILENAME);
        File output = new File(Environment.getExternalStorageDirectory(),
                fileName);
        if (output.exists()) {
            output.delete();
        }

        InputStream stream = null;
        FileOutputStream fos = null;
        try {

            URL url = new URL(urlPath);
            stream = url.openConnection().getInputStream();
            InputStreamReader reader = new InputStreamReader(stream);
            fos = new FileOutputStream(output.getPath());
            int next = -1;
            while ((next = reader.read()) != -1) {
                fos.write(next);
            }
            // successfully finished
            result = Activity.RESULT_OK;

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (stream != null) {
                try {
                    stream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (fos != null) {
                try {
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        publishResults(output.getAbsolutePath(), result);
    }

    private void publishResults(String outputPath, int result) {
        Intent intent = new Intent(NOTIFICATION);
        intent.putExtra(FILEPATH, outputPath);
        intent.putExtra(RESULT, result);
        sendBroadcast(intent);
    }
}

`Activity Implementation:`

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {

    private TextView textView;
    private BroadcastReceiver receiver = new BroadcastReceiver() {

        @Override
        public void onReceive(Context context, Intent intent) {
            Bundle bundle = intent.getExtras();
            if (bundle != null) {
                String string = bundle.getString(DownloadService.FILEPATH);
                int resultCode = bundle.getInt(DownloadService.RESULT);
                if (resultCode == RESULT_OK) {
                    Toast.makeText(MainActivity.this,
                            "Download complete. Download URI: " + string,
                            Toast.LENGTH_LONG).show();
                    textView.setText("Download done");
                } else {
                    Toast.makeText(MainActivity.this, "Download failed",
                            Toast.LENGTH_LONG).show();
                    textView.setText("Download failed");
                }
            }
        }
    };

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView = (TextView) findViewById(R.id.status);


    }

    @Override
    protected void onResume() {
        super.onResume();
        registerReceiver(receiver, new IntentFilter(
                DownloadService.NOTIFICATION));
    }
    @Override
    protected void onPause() {
        super.onPause();
        unregisterReceiver(receiver);
    }

    public void onClick(View view) {

        Intent intent = new Intent(this, DownloadService.class);
        // add infos for the service which file to download and where to store
        intent.putExtra(DownloadService.FILENAME, "index.html");
        intent.putExtra(DownloadService.URL,
                "http://www.vogella.com/index.html");
        startService(intent);
        textView.setText("Service started");
    }
}

Updare Activity UI from Service once processing done-- Using IBinder

Service Implementation:

import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Random;
public class LocalWordService extends Service {
    private final IBinder mBinder = new MyBinder();
    private List<String> resultList = new ArrayList<String>();
    private int counter = 1;

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        addResultValues();
        return Service.START_NOT_STICKY;
    }

    @Override
    public IBinder onBind(Intent intent) {
        addResultValues();
        return mBinder;
    }

    public class MyBinder extends Binder {
        LocalWordService getService() {
            return LocalWordService.this; //--> This will return the //service handle
        }
    }

    public List<String> getWordList() {
        return resultList;
    }

    private void addResultValues() {
        Random random = new Random();
        List<String> input = Arrays.asList("Linux", "Android","iPhone","Windows7" );
        resultList.add(input.get(random.nextInt(3)) + " " + counter++);
        if (counter == Integer.MAX_VALUE) {
            counter = 0;
        }
    }
}

`Activity Implementation:`

import android.app.ListActivity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends ListActivity implements ServiceConnection {
    private LocalWordService s;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        wordList = new ArrayList<String>();
        adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, android.R.id.text1, wordList);

        setListAdapter(adapter);
    }

    @Override
    protected void onResume() {
        super.onResume();
        Intent intent= new Intent(this, LocalWordService.class);
        bindService(intent, this, Context.BIND_AUTO_CREATE);
    }

    @Override
    protected void onPause() {
        super.onPause();
        unbindService(this);
    }

    private ArrayAdapter<String> adapter;
    private List<String> wordList;

    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.updateList:
                if (s != null) {
                    Toast.makeText(this, "Number of elements" + s.getWordList().size(),
                            Toast.LENGTH_SHORT).show();
                    wordList.clear();
                    wordList.addAll(s.getWordList());
                    adapter.notifyDataSetChanged();
                }
                break;
            case R.id.triggerServiceUpdate:
                Intent service = new Intent(getApplicationContext(), LocalWordService.class);
                getApplicationContext().startService(service);
                break;
        }
    }

    @Override
    public void onServiceConnected(ComponentName name, IBinder binder) {
        LocalWordService.MyBinder b = (LocalWordService.MyBinder) binder;
        s = b.getService();
        Toast.makeText(MainActivity.this, "Connected", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onServiceDisconnected(ComponentName name) {
        s = null;
    }
}

Saturday, 13 October 2018

Correct Implementation of hashcode and equals method

1. public class Test
2. {
3.  private int num;
4.  private String data;
5.
6.  public boolean equals(Object obj)
7.  {
8.   if(this == obj)
9.    return true;
10.   if((obj == null) || (obj.getClass() != this.getClass()))
11.    return false;
12.   // object must be Test at this point
13.   Test test = (Test)obj;
14.   return num == test.num &&
15.   (data == test.data || (data != null && data.equals(test.data)));
16.  }
17.
18.  public int hashCode()
19.  {
20.   int hash = 7;
21.   hash = 31 * hash + num;
22.   hash = 31 * hash + (null == data ? 0 : data.hashCode());
23.   return hash;
24.  }
25.
26.  // other methods
27. }

Thursday, 11 October 2018

Update UI every 5 seconds from background service

https://www.websmithing.com/2011/02/01/how-to-update-the-ui-in-an-android-activity-using-data-from-a-background-service/