Memory usage of application in Android sample code

WakeLock, PowerManager,uses-permission Android sample.
Main.java

public class Main extends Activity {
	    private SensorManager mSensorManager;
	    private PowerManager mPowerManager;
	    private WindowManager mWindowManager;
	    private WakeLock mWakeLock;
	    private Button button;
	    private TextView textView;

	    /** Called when the activity is first created. */
	    @Override
	    public void onCreate(Bundle savedInstanceState) {
	        super.onCreate(savedInstanceState);
try{
	        // Get an instance of the SensorManager
	        mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);

	        // Get an instance of the PowerManager
	        mPowerManager = (PowerManager) getSystemService(POWER_SERVICE);

	        // Get an instance of the WindowManager
	        mWindowManager = (WindowManager) getSystemService(WINDOW_SERVICE);
	        mWindowManager.getDefaultDisplay();

	        // Create a bright wake lock
	        mWakeLock = mPowerManager.newWakeLock(PowerManager.SCREEN_BRIGHT_WAKE_LOCK, getClass()
	                .getName());

	        setContentView(R.layout.main);
	        textView = (TextView)findViewById(R.id.textView1);
	        button = (Button)findViewById(R.id.button1);
	        button.setOnClickListener(mButtonStopListener);
	       
	        
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			Log.e("onCreate", e.getMessage());
		}
} // END onCreate
	    
	    View.OnClickListener mButtonStopListener = new OnClickListener() {
	    	public void onClick(View v) {
		        try {
					mWakeLock.release();
					textView.setText("mWakeLock.release()");
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
					Log.e("onPause",e.getMessage());
				}
	    	
	    	}
	    };

	    @Override
	    protected void onResume() {
	        super.onResume();
	        /*
	         * when the activity is resumed, we acquire a wake-lock so that the
	         * screen stays on, since the user will likely not be fiddling with the
	         * screen or buttons.
	         */
	        
	        try {
				mWakeLock.acquire();
				textView.setText("mWakeLock.acquire()");
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
				Log.e("onResume", e.getMessage());
			}

	    }

	    @Override
	    protected void onPause() {
	        super.onPause();

	        // and release our wake-lock
	        try {
				mWakeLock.release();
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
				Log.e("onPause",e.getMessage());
			}
	    }
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="//schemas.android.com/apk/res/android"
      package="cz.okhelp.Main"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="7" />
    <uses-permission android:name="android.permission.HARDWARE_TEST"></uses-permission>
<uses-permission android:name="android.permission.VIBRATE"></uses-permission>

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

    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".ScreenBrightnessActivity"
                  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>

If Android emulator freezes at startup, try create new virtual device with smaller memory and cpu usage, or select older version of Android, or buy new pc with higher performance.

1. open AVD MANAGER


2. press Create Virtual Device


3. select Device with small memory usage (e.g. 480x800 of resolution) - Next


4. check - Show downloadable ....


5. Download - lower version of system Android, select, press - Next


6. check data, Show Advanced Settings, check Use host... and press Finish

Try this trick.
In AndroidManifest - activity tag write this code
android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize|smallestScreenSize"
App hold data of a views if will to rotation of device.

       <activity
 android:name=".Tests_Activity"
 android:label="@string/app_name"
 android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize|smallestScreenSize" />

Why the app selects data from basic layout folder if smallest width is higher then the number in folder name?
Example 1
layout-sw600dp values-sw600dp (smallest width sw for data usage from this folder is 600dp density independent pixel!!!!!)
Device screen resolution is 1200 x 900 px (pixel) Wow, app to be select data from sw600dp folder! Realy?
DPI of device screen - dot per inch (pixel per inch) is 480 pixel it is wery important number!

1. App selects smallest dimension of screen. In our case 900 px
   Medium screen have 160 dpi (The density-independent pixel is equivalent to one physical pixel on a 160 dpi screen, which is the baseline density assumed by the system for a "medium" density screen.).



2. App calculate ratio 480 / 160 = 3 (The conversion of dp units to screen pixels: px = dp * (dpi / 160))



3. App calculate smallest dimesnion of screen in dp 900 / 3 = 300 dip or dp (density independed pixel).



4. App selects data from basic values and layout folder because sw600dp is greater than 300dp.

In our case smallest dimension of screen must be at least 1800 real - physical pixels (1800 px / 3 ratio(dpi/160) = 600 dp (dip density independend pixels) to be used data from folders values-sw600dp and layout-sw600dp.


Example 2 see Example 1 abouve
Device: Nexus 7 (2012) selected from Android Studio tool layout editor
Resolution: 800x1280 px
DPI: tvdpi (approximately 213dpi)
Ratio: 1.33 (213 / 160)
Smallest width in px: 800
Convert px to dp: 601.5 (800 / 1.33)
Result:Smallest width is 601.5dp The App to be used data from folders values-sw600dp and layout-sw600dp.

ListFragment show only one item issue

Try to change layout_width to 0dp

   <fragment android:name="cz.okhelp.android.fragchangfromlist.ArticleFragment"
              android:id="@+id/article_fragment"
              android:layout_weight="2"
              android:layout_width="0dp"
              android:layout_height="match_parent" />
<!--todo LAYOUT_WIDTH have to be 0dp !!!!!!!!!!!!!!!!!!!!! -->

    <FrameLayout android:id="@+id/article_fragment"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="2" />