Unable to execute dex: Multiple dex files define Eclipse Android

If You have old PC (Android in emulator with high screen resolution uses a lot of memory) or your testing phone have small screen, You can try this trick.
Rename layout folder for small device screen f.g. from layout into layout-swXXXdp and a large layout-sw600dp into layout.
Your phone with small screnn will do select xml file from renamed layout folder (for small screen).
You can to testing rotation with device en stability of fragments if an application changed orientation.
If you have old pc, you can try to make a new virtual device running on older version of Android, which uses less memory of computer.
For testing of rotation stability - application orientation changed - use on emulator Ctrl+F11, Ctrl+F12 key (Windows).

Important
Before the release of application, you have to rename layout folder to older name layout-sw600dp and layout-swXXXdp to layout.

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.

Change the title associated with this activity. If this is a top-level activity, the title for its window will change. If it is an embedded activity, the parent can do whatever it wants with it.

 String sTitle = "My new title";
 setTitle(sTitle);

Start Stop Stopwatch Timer Android example source code.

private static long mStartTime = 0L;
Calendar cal;
TextView hTextViewVypis = (TextView)findViewById(R.id.idTextVypis);

void start(){
            cal = Calendar.getInstance();
            mStartTime = cal.getTimeInMillis();
}

void stop(){
     prinOutStopWatchTime();
}


    private void prinOutStopWatchTime() {
    	final long start = mStartTime;
    	
    	cal = Calendar.getInstance();
    	long stopTime = cal.getTimeInMillis();
    	long millis = stopTime - start;
    	long milisekundy = millis % 1000;
    	int seconds = (int) (millis / 1000);
    	int minutes = seconds / 60;
    	seconds     = seconds % 60;
    	int hour = minutes / 60;
    	hour = hour % 60;
    	
    	if (seconds < 10) {
    		hTextViewVypis.setText(hour +  ":" + minutes + ":0" + seconds + ":" + milisekundy);
    	} else {
    		hTextViewVypis.setText(hour  +  ":" + minutes + ":" + seconds + ":" + milisekundy);            
    	}
    	
    }

Try some solution - each individually or all

1. Check AndroidManifest.xml activity declaration
   

   <activity
               android:name=".EnableProfileActivity"
               android:label="@string/app_name" />

   
   


2. Delete BUILD folder in module tree and Clean / Rebuild project


3. Restart Android Studio