How to save the state of Activity - Android

AlertDialog like MessageBox by WinApi:
If error: Unable to add window -- token null is not for an application
try change get Context.

// you can put this text into some function body or case in switch statement
                new AlertDialog.Builder(this)
                    .setMessage("Hello boys!!!")
                    .setPositiveButton("OK", null)
                    .show();

Context context = getApplicationContext();
	AlertDialog.Builder builder = new AlertDialog.Builder(context);
	builder.setTitle("Select font size");
	final CharSequence[] chsSize= { "Small", "Medium", "Large"};
	builder.setSingleChoiceItems(chsSize, 0 /*sel.item*/, 
	new DialogInterface.OnClickListener() {
 	    public void onClick(DialogInterface dialog, int item) {
	    		 Toast.makeText(context, "Hello from dialog!!!", Toast.LENGTH_SHORT).show();
	        dialog.dismiss();
	    }
	});
	AlertDialog alert = builder.create();
	alert.show();
    

Brand	Motorola
Model (codename)	Droid Razr
Price (cena, včetně DPH v KCZ)	10800 / 06.2012
Display size in Inch (v palcích)	4.3
Display-resolution	540x960
Dotek-typ	capacitive
CPU typ	TI 4430
CPU MHz	1.2 GB
CPU core	2
L2 cache
RAM	1024
ROM	15600
GPU	SGX540
NenaMark2 Benchmark
GPU-GLBenchmark	3299
Baterie mAh	1780
Foto MPx	8
Autofocus	AF
Video	HD video 30 frames/s
Official Android ICS	Google Android 2.3.5 (Gingerbread)
CyanogenMod support
Dotek-prstů-max	10
Display-ppi	256
Display-retina	79%
Networks
Connectivity	GSM: 850/900/1800/1900 MHz, EDGE, GPRS 3G: 900/2100 MHz, HSDPA, HSUPA, HSPA+ Bluetooth: 4.0 (EDR, A2DP, FTP, PBAP, AVRCP) Wi-Fi: 802.11b/g/n PC: microUSB, USB 2.0, microHDMI Senzors: proximity, gyroskop, akcelerometr GPS: yes, A-GPS, digital compas
Note	Super AMOLED Display

Motorola Droid Razr image

float, double is NaN isNaN() isInfinite() Java Android example.

float f = 0.f;
boolean bIsNaN = Float.isNaN(f);
boolean bIsInfinite = Float.isInfinite(f);

 double d = Math.sqrt(-10);
 boolean b = Double.isNaN(d);

Bitmap size calculation:
bmpHeight * bmpWidth
For example:
Resolution of image 1024x860 = 880 640 pixels
If every pixel get 4 byte of memory:
880 640x4= 3 522 560 (3.5MB)

Get bitmap size without allocation of memory:

   	BitmapFactory.Options options = new BitmapFactory.Options();
        // If set to true, the decoder will return null (no bitmap), but the out... fields will still
        // be set, allowing the caller to query the bitmap without having to allocate the memory for its pixels. 
    	options.inJustDecodeBounds = true; 
    	BitmapFactory.decodeResource(getResources(), R.drawable.my_image, options);
    	int imageHeight = options.outHeight; // 1024
    	int imageWidth = options.outWidth; // 860
    	String imageType = options.outMimeType; // .jpg .png .gif
 

Get Memory size:
Make your bitmap not bigger as maxMemory size
final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);

    float density = getResources().getDisplayMetrics().density;

    Debug.MemoryInfo memoryInfo = new Debug.MemoryInfo();
    Debug.getMemoryInfo(memoryInfo);
    final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);
    final int freeMemory = (int) (Runtime.getRuntime().freeMemory() / 1024);
    String memMessage = String.format(
        "Free=%d kB,

MaxMem=%d kB,

 Memory: Pss=%.2f MB, Private=%.2f MB, Shared=%.2f MB",
        freeMemory,
        maxMemory,
        memoryInfo.getTotalPss() / 1024.0,
        memoryInfo.getTotalPrivateDirty() / 1024.0,
        memoryInfo.getTotalSharedDirty() / 1024.0);
    ((TextView)findViewById(R.id.textViewInfo)).setText(memMessage );

Click to Android version combobox - drop down menu and select your version, which just using (have instaled). For example: You updated ADT by SDK manager, but forget to update Android version. You can use lower version from drop down menu, which using your project, or do update of Android by SDK manager.