Motorola Droid RAZR

No resource found that matches the given name - error examples.
Exist resource file?
Is code written correctly?

// No resource found that matches the given name (at id with value @id/myButton).
 android:id="@id/myButton" // invalid id notation
 android:id="@+id/myButton" // correct


 // No resource found that matches the given name 
// (at icon with value @drawable/icons).
// exist file icons in res/drawable folder?
<application android:icon="@drawable/icons" 

//No resource found that matches the given name 
//(at theme with value @style/MyThem).
<activity android:name=".Main"
                  android:label="@string/app_name"
                  android:theme="@style/MyThem">

// Exist style MyThem  in styles.xml ?  No only MyTheme
<style name="MyTheme" parent="android:Theme">
        <item name="android:windowTitleSize">50px</item>
</style>



// exist file my_background in folder drawable ?
android:background="@drawable/my_background" // 

// no resource found that matches the given name(at "label" with value "@string/app_name")
// have you the string resource defined in res/values/strings.xml ?
<string name="app_name">"My App"</string>

Calendar dateOfYourBirth = new GregorianCalendar(1998, Calendar.SEPTEMBER, 17); Calendar today = Calendar.getInstance(); Android example.

public class HoriziontalScrollActivity extends Activity {
	TextView txtV;
	Context cntx;
	
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        txtV = (TextView)findViewById(R.id.idLabel);
        cntx = this;
        StringBuilder strBuild = new StringBuilder();

        // enter your date of birth
        Calendar dateOfYourBirth = new GregorianCalendar(1998, Calendar.SEPTEMBER, 17);
        Calendar today = Calendar.getInstance();
        int yourAge = today.get(Calendar.YEAR) - dateOfYourBirth.get(Calendar.YEAR);
        dateOfYourBirth.add(Calendar.YEAR, yourAge);
        if (today.before(dateOfYourBirth)) {
            yourAge--;
        }  
        strBuild.append("You are " + yourAge + " old!");
         txtV.setText(strBuild);
    }
}

public class MainActivity extends Activity {
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(new SampleView(this));
	}

	private static class SampleView extends View {

		// CONSTRUCTOR
		public SampleView(Context context) {
			super(context);
			setFocusable(true);

		}
		@Override
		protected void onDraw(Canvas canvas) {
			Paint paint = new Paint();
			
			canvas.drawColor(Color.GREEN);
            
            Bitmap b = Bitmap.createBitmap(200, 200, Bitmap.Config.ALPHA_8);
             paint.setColor(Color.BLUE);
            
           Canvas c = new Canvas(b);
           c.drawRect(0, 0, 200, 200, paint);
           
           canvas.drawBitmap(b, 10,10, paint);
		}

	}
}

First: AdView is in XML file

<com.google.android.gms.ads.AdView
    xmlns:ads="//schemas.android.com/apk/res-auto"
    android:id="@+id/adView"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    ads:adUnitId="MY_AD_UNIT_ID"
    ads:adSize="BANNER"/>

// onResume
AdView adView = (AdView)this.findViewById(R.id.adView);
AdRequest adRequest = new AdRequest.Builder()
    .addTestDevice(AdRequest.DEVICE_ID_EMULATOR)
    .addTestDevice("TEST_DEVICE_ID")
    .build();
adView.loadAd(adRequest);

Second: Using AdView in Fragment with LinearLayout
Resolve error in ADT Graphical layout editor:
The following classes could not be instantiated:
- com.google.android.gms.ads.AdView

// layout in xml file
    <LinearLayout
        android:id="@+id/layout"
              android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

// java class with fragment in Fragment class or in Activity class
private static AdView adView;
        @Override
		public void onResume(){  
                super.onResume();
                 try {
                	 // in xml is empty layout
					adView = new AdView(getActivity());
					adView.setAdUnitId("ca-app-pub-626/638103xxxxxxx");
					adView.setAdSize(AdSize.BANNER);  
					
                	                LinearLayout layout = (LinearLayout)getView() .findViewById(R.id.layout);
					layout.addView(adView);
					
					AdRequest adRequest = new AdRequest.Builder().build();   
					adView.loadAd(adRequest);

				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
        }

More about:
https://developers.google.com/mobile-ads-sdk/docs/admob/android/play-migration?hl=it

Terms Screen size, density, density independent pixel, resolution as a picture - pictogram.


Test your knowledge
Q: How to find out the phone screen size?
A: (By length of display diagonale in inch -  Not to measure a diagonal of device!!!)

Q: What resolution has 720 x 1280 display?
A: (921600 pixels)

Q: What does it mean "240 dpi" screen density?
A: (Display have density 240 x 240  dots - "Tri-color LED etc." - per every physical (real) square inch. If you have icon 240x240 pixels, this will just occupy an area of one square inch on the display.)

Q: Phone have screen density 240 dpi. Image for 160 dpi screen density have size 128x 128 pixels. What will be the size of the image for 240 dpi screen density?
A: (Calculate the virtual pixels size.   128 * (240/160)  =  192.  You have to resize image to new size 192 x 192 physical pixels and put into folder drawable-hdpi (high) ~240dpi  for phone with screen density 240 dpi. ) or use density independend pixels 128dp x 128dp.