float in Java example code

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Android development
Java float is 32 bit single precision type and used when fractional precision calculation is required.

Java float je 32 bitů veliké číslo sloužící především pro přesný výsledek za desetinnou tečkou například při dělení čísel. Pro větší přesnost použíijte 64 bitový typ Double.


		// declaration and assignment of value  type float
		float x = 18.41785f;
		//print formated  value
		System.out.printf("The value of x is %.3f%n", x); // 18.418
                
                // declaring more variables in single statement
                float f1 = 12.4F, f2 = 564.5F, f3 = 14.589F;

		// float range of value
		System.out.println(Float.MIN_VALUE); // 4E-45
		System.out.println(Float.MAX_VALUE); // 4028235E38

		// is NaN  Not-a-Number
		float f = (float) Math.sqrt(-15);
		boolean bNaN = Float.isNaN(f);
		System.out.print(bNaN); // true
		
                // check if a string is a valid number in Java example
                // convert string to float Java example
		String sF = "12.8";
		float fParse = Float.parseFloat(sF);

	       // convert strings to numbers
	      String sFl = "15.48";
	      float fFromString = (Float.valueOf(sFl)).floatValue();

// float to string in Java example code
Float fObj = new Float(68.5);
String str = fObj.toString();
// else 
Float fS = 11.6f;
String sFloat = fS.toString();

              // compare two float variables
	      Float fComp1 = 4.3f;
	      if(fComp1.equals(4.3f))
	  		System.out.print("true");

	    // compares the two specified float values in Java example
	    int i =	Float.compare(11.5f, 11.7f); // -1 first < second
	    // 0 first == second
	    // 1 first > second
	    System.out.print(i);

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RadioButton RadioGroup Java Android example | radiobutton-radiogroup-android-example

RadioButton RadioGroup Android example source code for Android developer
Example for *.xml files


       <RadioGroup android:id="@+id/idRadio_group"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginLeft="20dp"
            android:orientation="vertical">

            <RadioButton android:id="@+id/idRadio_1"
                android:text="@string/textLabel_1"/>
            <RadioButton android:id="@+id/idRadio_2"
                android:text="@string/textLabel_2"/>
            <RadioButton android:id="@+id/idRadio_3"
                android:text="@string/textLabel_3"/>

        </RadioGroup>

Example for *.java files


// import
import android.widget.RadioGroup;
// get handle of RadioGroup
RadioGroup  mRadioGroup = (RadioGroup) findViewById(R.id.idRadio_group);

// which RadioButton is selected for example in some function body
         int nUnits = 10; // decimetry
    	 int nIdRadio = mRadioGroup.getCheckedRadioButtonId();
    			if(nIdRadio == R.id.idRadio_1) nUnits = 1; // metr
    			else if(nIdRadio == R.id.idRadio_2) nUnits = 10; // decimetr
    			else if(nIdRadio == R.id.idRadio_3) nUnits = 100; // cm
    			else if(nIdRadio == R.id.idRadio_4) nUnits = 1000; // mm


// listener for RadioGroup Java Android example
       mRadioGroup.setOnCheckedChangeListener(
                new RadioGroup.OnCheckedChangeListener() {
                    public void onCheckedChanged(RadioGroup group,
                            int checkedId) {
                        Log.v("Selected", "New radio item selected: " + checkedId);
                        recordNewUIState();
                    }
                });

192

Samsung Galaxy Pocket - Android | samsung-galaxy-pocket-android

Nejmenší telefon od Samsungu s Androidem se někdy přidává i jako dárek k zakoupenému zboží, přesto tento telefon toho za svou cenu něco přes 2 000 korun umí hodně.
Technické parametry Samsung Galaxy Pocket
Rozměry a hmotnost: 103,70 × 57,50 × 12 mm, 97 g
Sítě GSM 850 / 900 / 1800 / 1900 MHz, W-CDMA (3G) 900 MHz / 2 100 MHz
Displej TFT TN, 2,80" (320 × 240 px), dotykový: kapacitní
Procesor 832 MHz
Paměť RAM 256 MB, vnitřní paměť 3 GB, paměťové karty microSD
Operační systém Android 2.3, údajně nelze upgradovat
Hudba: mp3, aac, wav, wma
Video: mp4, 3gp, 320 × 240 px, 15 FPS
Fotoaparát 2 Mpx
Navigace vestavěná GPS, elektronický kompas
Baterie 1 200 mAh, pohotovostní doba: 312 hodin
Cena něco přes 2 000 korun / léto 2012

samsung-galaxy-pocket

294

Get Bitmap Size Get Free Memory Exception Android | get-bitmap-size-get-free-memory-exception-android

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 );

312

Import project Android Eclipse | import-project-android-eclipse

Import a new Android project for example downloaded from internet via Eclipse into project folder.

Right click into projects explorer in Eclipse and select Import

Android

Existing Android Code Into Workspace

Root Directory (select folder of downloaded project)

Check your downloaded project

Check Copy project into Workspace

Finish (press)

309

Where Eclipse stored Settings and Templates Java Code | where-eclipse-stored-templates-java-code


C:\documents\workspace\.metadata\.plugins\org.eclipse.core.runtime\.settings\org.eclipse.jdt.ui.prefs

Editace: 2011-09-26 20:49:50
Počet článků v kategorii: 397
Url:float-in-java-example-code

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