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SD card SDcard get external storage directory Android


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Environment.getExternalStorageDirectory()+ File.separator


Boolean canWrite =	Environment.getExternalStorageDirectory().canWrite() ;
if(canWrite){
File f = new File(Environment.getExternalStorageDirectory()
                        + File.separator + "my_image.jpg")
f.createNewFile();
}else{

}

AndroidManifest.xml
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

397LW NO topic_id




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Další témata ....(Topics)


257

Two boolean as one parameter value in function Java | two-boolean-as-one-parameter-value-in-function-java



boolean fc(boolean b) {
	return b;
}// end fc
		boolean bA = true;
		boolean bB = true;
		boolean bC = bA || bB; // true

		bA = true;
		bB = false;
		bC = bA || bB; // true

		bA = false;
		bB = true;
		bC = bA || bB; // true

		bA = false;
		bB = false;
		bC = bA || bB; // false
		
			if(!fc(bB||bA))
			System.out.println("false"); // false
                        else 
			System.out.println("true"); 


78

Goto labeled statement in Java example | goto-labeled-statement-in-java-example


Goto in for cycle Java example source code.
MainClass.java

public class MainClass {
	public static void main(String[] arg) {
		String[] arrayOfString = {"nothing", "Hello", "people"
				, "bye-bye", "hello", "world!", "end" };
		
	    OuterLoop: for (int i = 0;i<6; i++) {
	        for (int j = 0; j < arrayOfString.length; j++) {
	        	if (arrayOfString[j].equals("world!")) {
	            continue OuterLoop; // as goto from Csharp, or C/C++
	          }
	          System.out.println(arrayOfString[j]);
	          System.out.println(i);
	          if (i == 1) {
	        	  System.out.println("break");
	        	  
	        	  break OuterLoop;
	          }
	        }
	      }
		
	}
}
/*
nothing
0
Hello
0
people
0
bye-bye
0
hello
0
nothing
1
break
*/
295

Shuffle array int string Java Android | shuffle-array-int-string-java-android



String [] arOfStrings = {"one", "two", "three"};
List<String> mListOfStrings = new ArrayList<String>(Arrays.asList(arOfStrings));
Collections.shuffle(mListOfstrings);
String str = mListOfStrings.get(2);// 2 is index of pozition an element


int [] arOfInt = {1, 2, 3};
List<Integer> mListOfInt = new ArrayList<Integer>(Arrays.asList(arOfInt));
Collections.shuffle(mListOfInt);
40

Spinner ComboBox DropDown set on selected item listener setOnItemSelectedListener Java Android example | spinner-combobox-set-on-selected-item-listener-setonitemselectedlistener-java-android-example


Spinner, ArrayAdapter, setOnItemSelectedListener, onItemSelected, setDropDownViewResource

MainClass.java

public class Vypocet extends Activity {
 Spinner   hSpinnerMetry;
// .......
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

	       hSpinnerMetry = (Spinner) findViewById(R.id.idSpinnerMetry);
	        ArrayAdapter<CharSequence> adapterMetry = ArrayAdapter.createFromResource(
	        		this, R.array.metry_array, android.R.layout.simple_spinner_item);
	        adapterMetry.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
	        hSpinnerMetry.setAdapter(adapterMetry);
			
	           hSpinnerMetry.setOnItemSelectedListener(
	                    new OnItemSelectedListener() {
	                        public void onItemSelected(
	                                AdapterView<?> parent, View view, int position, long id) {
	                        int nPos = position;
	                        }

	                        public void onNothingSelected(AdapterView<?> parent) {
	                        
	                        }
	                    });	        

      }
}



strings.xml


<string-array name="metry_array">
<item>m</item>
<item>dm</item>
<item>cm</item>
<item>mm</item>
</string-array>


16

float in Java example code | float-in-java-example-code


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);




Editace: 2013-12-09 10:08:22
Počet článků v kategorii: 397
Url:sd-card-get-external-storage-directory-android

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