Android Studio lock unlock file make read only or writable

AdMob in Android emulator not visible?
You have to using some from this libraries:
GoogleAdMobAdsSdk-4.3.1.jar
GoogleAdMobAdsSdk-6.0.1.jar
GoogleAdMobAdsSdk-6.2.1.jar

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="//schemas.android.com/apk/res/android"
    package="cz.okhelp.admob"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="13"
        android:targetSdkVersion="16"/>

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

    <application android:icon="@drawable/ic_launcher" android:label="@string/app_name">
       <meta-data 
        android:value="a14d932xxxxxxxx" 
        android:name="ADMOB_PUBLISHER_ID" />
        <activity android:name=".AdmobActivity"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

<activity android:name="com.google.ads.AdActivity"
 android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize|smallestScreenSize" />
</application>
</manifest>

onCreate in your Activity.java

		@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
     			AdViw adView = new AdView(this, AdSize.BANNER, "a14d932xxxxxxxxx");//MY_AD_UNIT_ID
    			LinearLayout layout = (LinearLayout)findViewById(R.id.idReklamaLayout);
				// Add the adView to it
    			layout.addView(adView);
				// Initiate a generic request to load it with an ad
				AdRequest adRequest = new AdRequest();
    			//adRequest.setTesting(true);
    			adRequest.setGender(AdRequest.Gender.MALE);
    			adView.loadAd(adRequest);
    }

main.xml (res/layout)

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="//schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello" />
<LinearLayout xmlns:android="//schemas.android.com/apk/res/android"
android:id="@+id/idReklamaLayout"
android:orientation="vertical"
android:gravity="center"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="3" />

</LinearLayout>

Issue: After after renaming package this problem occurred "R cannot be resolved to a variable".

Solution: Try Clean your project Project » Clean » Clean projects selected below » select your project and click OK.

Try to delete the invalid code and type it again:

LinearLayout layout = (LinearLayout) findViewById(R.id.layout); // delete R.id.layout
LinearLayout layout = (LinearLayout) findViewById(); 
LinearLayout layout = (LinearLayout) findViewById(R.id.layout); // re-write this code R.id.layout

Try this solution:

  				
AdView adView = new AdView(getApplicationContext());//in menu inflater getActivity()
adView.setAdUnitId("ca-app-pub-87***yourNumber");
adView.setAdSize(AdSize.BANNER); 					
LinearLayout linLay = (LinearLayout)findViewById(R.id.idReklamaLayout);
// Add the adView to it
linLay.addView(adView);
// Initiate a generic request to load it with an ad
if(Build.MANUFACTURER.equals("unknown")) {
// Emulator
AdRequest.Builder.addTestDevice("B3EEABB8EE11C2BE770B684D95219ECB"); // to get test ads on this device.
AdRequest adRequest = new AdRequest.Builder()
 .addTestDevice(AdRequest.DEVICE_ID_EMULATOR)        // All emulators
 .addTestDevice("B3EEABB8EE11C2BE770B684D95219ECB")  // Emulator id you will get in the LogCat verbose
 .build();
			
adView.loadAd(adRequest);
	  			/* */
}else {
 // Not Emulator
// Initiate a generic request to load it with an ad
AdRequest adRequest = new AdRequest.Builder().build();   
adView.loadAd(adRequest);/**/
}

First cteate big icon 512x512 px formtat .PGN in graphics editor as Photoshop, Gimp, Piant.NET and save image.
If you create new project via Eclipse and choice your 512x512 image for ic_launcher.
Eclipse will make all icons from this image for new application very well.

If you using GoogleAdMobAdsSdk-4.0.4.jar in your project and set android:targetSdkVersion="17" in AndroidManifest.xml , ads will not visible on emulator with Android 4.0.3 or 4.1.
You have to set as android:targetSdkVersion="17"

<uses-sdk android:minSdkVersion="4" 
        android:targetSdkVersion="17" />

Update project.properties file - row with target to 17:

# Project target.
target=android-17