techworks

In previous post , I have shown how we can start the scanning of wifi and receive the results using BroadcastReceiver. The problem with this approach is it consumes battery each time scanning is started. To avoid this there is another way: Listen to scan results initiated by other applications or by OS. You need to add following in manifest. <receiver android:name="com.example.receivers.WifiScanCompleteReceiver" > <intent-filter> <action android:name="android.net.wifi.SCAN_RESULTS" /> </intent-filter> </receiver> Code for WifiScanCompleteReceiver.java is as follows: package com.example.receivers; //imports public class WifiScanCompleteReceiver extends BroadcastReceiver { public WifiScanCompleteReceiver() {} @ Override public void onReceive(Context context, Intent intent) { Log.d(HelperUtils.getInstance().getApplicationName(), "Wifi scan result received."); Vector < String > WifiNames = new Vector ...

A good link for formatting and showing code in Blogger. http://stackoverflow.com/questions/10335463/how-to-setup-syntax-highlighter-on-blogger/10848816#10848816

Following code shows how to add an alarm for a given time along with setting a number as extra to identify which alarm was triggered. ProfileSettings.java is a class containing following fields with getter setter. Class ProfileSettings {     private long _time;     private int _type;     private int _id; } Code to add the alarm is as follows: public void addAlarmEvent(ProfileSettings setting) { Context context = Main.getInstance().getContext(); AlarmManager alarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE); Intent intent = new Intent(context, AlarmBroadcastReceiver.class); intent.putExtra(AlarmBroadcastReceiver.PROFILE_CODE, setting.getProfileCode()); PendingIntent pendingIntent = PendingIntent.getBroadcast(context, setting.getEventId(), intent, PendingIntent.FLAG_UPDATE_CURRENT); Long time = setting.getTime(); alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, time, AlarmManager.INTERV...

For scanning wifi access points at interval of 30 seconds, I have the following code. However I strongly discourage frequent scanning as it will drain the battery very fast. Following code registers for a broadcast receiver and requests the Wifi scan. new Thread( ) { public void run( ) { WifiManager manager = (WifiManager) Main.getInstance( ).getContext( ) .getSystemService( Context.WIFI_SERVICE ); while ( true ) { IntentFilter i = new IntentFilter( ); i.addAction( WifiManager.SCAN_RESULTS_AVAILABLE_ACTION ); Main.getInstance( ).getContext( ).registerReceiver( new WifiScanCompleteReceiver( ), i ); boolean a = manager.startScan(); try { Thread.sleep( 30000 ); } catch ( InterruptedException e ) { } Log.d( HelperUtils.getInstance( ).getApplicationName( ), "New Wifi scan started." ); } } } .start( ); In this code Main.getInstance( ).getContext( ) returns _context = getApplicationContext( ) . Next write a broadcast receiver to liste...

A good link for Android developers. Power usage by various components in Android. https://source.android.com/devices/tech/power.html Types of coroutine scopes https://vladsonkin.com/android-coroutine-scopes-how-to-handle-a-coroutine/

This code returns string which can be shown in a field having width=width, 5 pixel margin on left and 5 pixel on right. private String getTextShown( String completeString, int width ) { if ( completeString == null ) return null; width = width - 10; Font font = listfield.getFont( ); if ( font.getAdvance( completeString ) < width ) return completeString; for ( int i = completeString.length( ) - 1; i > 0; i-- ) { completeString = completeString.substring( 0, i ); StringBuffer tempBuffer = new StringBuffer( completeString ); tempBuffer.append( "..." ); String temp = tempBuffer.toString( ); if ( font.getAdvance( temp ) < width ) { return temp; } } return completeString; } This can be called from protected void paint( Graphics graphics ) { String stringToDraw = getTextShown( ...