Android Studio formatting code Ctrl + Alt + L

Try add to AndroidManifest.xml configChanges for your Activity
android:configChanges="keyboardHidden|orientation|screenSize"

 <activity android:name=".MainActivity"
                  android:label="@string/app_name"
                  android:configChanges="keyboardHidden|orientation|screenSize"
                  >

      Spinner  _spin1 = (Spinner) findViewById(R.id.spinLangFirst);
      ArrayAdapter<String> adapterJazyky = new ArrayAdapter<String>(this,
              R.layout.spinner_text_layout.xml, {"one","two","etc...."});
      adapterJazyky.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
      _spin1.setAdapter(adapterJazyky);

spinner_text_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="//schemas.android.com/apk/res/android"
          android:id="@+id/spinnerText"
          android:layout_width="fill_parent"
          android:layout_height="wrap_content"
         
         android:textSize="20sp"
/>

If you want download some *.apk file from internet and try on your emulator you get error than you have to install SD card. You have to closing Android emulator.
Mount Android emulator SD card instruction

1. In Eclipse go in menu Window - Android SDK and Avg Manager


2. Select Virtual devices


3. Select AVD Name where you need install SD card


4. Click on Edit button


5. In open dialog go to SD card - Size: and write 500


6. Press button Edit AVD


7. Run AVD emulator

Image how install SD card on Android emulator in Eclipse.

Switch statement with numbers and array of strings Java example.

public class MainClass {
	public static void main(String[] arg) {
		String[] arrayOfString = { "One", "Two", "Three", "Four" };

		int i = 2;
		switch (i) {
			case 1: {
				System.out.println(arrayOfString[i]);
				break;
			}
			case 2: {
				System.out.println(arrayOfString[i]);
				break;
			}
			case 3: {
				System.out.println(arrayOfString[i]);
				break;
			}
			default: {
				System.out.println("Enter a valid value.");
			}
		} // END of switch
	}
}
/*
 * Three
 */

Possible:

case 1:
 System.out.println(arrayOfString[i]);
break;

// i love this notation 
case 1:{
 System.out.println(arrayOfString[i]);
}break;

case 1:{
 System.out.println(arrayOfString[i]);
 break;
}

RectF, drawRoundRect(),

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);
           Canvas c = new Canvas(b);
           RectF rectF = new RectF();
           rectF.set(5,5,150,150);
           c.drawRoundRect(rectF, 10, 10, paint);
           
            paint.setColor(Color.RED);
           
           canvas.drawBitmap(b, 10,10, paint);
		}

	}
}