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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);



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18

long in java example | long-in-java-example


Android development

long is 64 bit signed type and used when int is not large enough to hold the value.

long je celé číslo 64 bitů -9223372036854775808 +9223372036854775807 a používá se tam, kde typ int není schopen pojmout takovou hodnotu čísla.


		// declaration and assignment of value type long
		long n = 22337203685477580L;
		// print formated value
		System.out.printf("The value of x is %d%n", n); // 22337203685477580
		System.out.format("%+,8d%n%n", n); // +22 337 203 685 477 580

		// declaring more variables in single statement
		long lo1 = 12L, lo2 = 56, lo3 = 1455555555589L;

		// long range of value
		System.out.println(Long.MAX_VALUE); // 9223372036854775807
		System.out.println(Long.MIN_VALUE); // -9223372036854775808

		// check if a string is a valid number in Java example
		// convert string to long Java example
		String sLong = "1288888888888888";
		long longParse = Long.parseLong(sLong);

		// convert strings to numbers
		long longFromString = (Long.valueOf(sLong)).longValue();

		// long to string in Java example code
		Long longObj = new Long(229999999999L);
		String str = longObj.toString();
		// else
		Long longS = 888888888888L;
		String strLong = longS.toString();

		// compare two long variables
		Long longComp1 = 5555L;
		if (longComp1.equals(55555555L))
			System.out.print("true");

		// compares the two specified long values in Java example

		int i = longS.compareTo(444444L); // -1 first < second
		// 0 first == second
		// 1 first > second
		System.out.print(i);
19

How set focus on View Android development example | how-set-focus-on-view-android-development-example


Set focus on a View in Android application example source code for Button, EditText, View, TextView, isFocused(), requestFocus() .


// set focus on Button Android example
 private Button mRightButton;
 mRightButton = (Button) a.findViewById(R.id.rightButton);
 mRightButton.requestFocus();
// boolean isFocused() 
boolean b = mRightButton.isFocused(); // true or false

// set focus on TextView directly Android example
((TextView) findViewById(R.id.myText)).requestFocus();

// set focus on View Android example
private View mView;
mView = findViewById(R.id.showAll);
mView.requestFocus();

// set focus on EditText Android example
private EditText mEdit;
mEdit = (EditText)findViewById(R.id.myEdit);
mEdit.requestFocus();
33

Spinner ComboBox DropDown List Android example code | spinner-combobox-dropdown-list-android-code-example


Spinner in Android application is equivalent of ComboBox in WinApi.
Spinner get selected item to string example.
Spinner get selected item position to int example.

Main activity class MainComboBox.java

public class MainComboBox extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Spinner spinner = (Spinner) findViewById(R.id.spinner);
        ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(
                this, R.array.countries_array, android.R.layout.simple_spinner_item);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(adapter);
        spinner.setOnItemSelectedListener(new MyOnItemSelectedListener());

        Button myButton =(Button)findViewById(R.id.button1);
        myButton.setOnClickListener(new Button.OnClickListener() {
            public void onClick(View v) {
            	
            Spinner sp =	(Spinner)findViewById(R.id.spinner);
            String spinnerString = null;
            spinnerString = sp.getSelectedItem().toString();
            int nPos = sp.getSelectedItemPosition();
            
             
                Toast.makeText(getApplicationContext(), "getSelectedItem=" + spinnerString,
                    Toast.LENGTH_LONG).show();
                Toast.makeText(getApplicationContext(), "getSelectedItemPosition=" + nPos,
                		Toast.LENGTH_LONG).show();
            }
        });
    }
}



File MyOnItemSelectedListener.java

public  class MyOnItemSelectedListener implements OnItemSelectedListener {

    public void onItemSelected(AdapterView<?> parent,
        View view, int pos, long id) {
      Toast.makeText(parent.getContext(), "Item is " +
          parent.getItemAtPosition(pos).toString(), Toast.LENGTH_LONG).show();
    }

    public void onNothingSelected(AdapterView parent) {
      // Do nothing.
    }
}


strings.xml

<resources>
    <string name="hello">Hello World, MainComboBox!</string>
    <string name="app_name">ComboBox</string>
    <string name="prompt">Choose a country</string>
    <string-array name="countries_array">
        <item>China</item>
        <item>India</item>
        <item>USA</item>
        <item>Indonesia</item>
        <item>Brazil</item>
        <item>Pakistan</item>
        <item>Nigeria</item>
        <item>Bangladesh</item>
        <item>Russia</item>
    </string-array>    
</resources>


main.xml

<LinearLayout xmlns:android="//schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:padding="10dip"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content">
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dip"
        android:text="@string/prompt"
    />
    <Spinner 
        android:id="@+id/spinner"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:prompt="@string/prompt"
    />
    <Button android:text="Button" android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content"></Button>

</LinearLayout>




318

Ad baner without GoogleAdMobAdsSdkAndroid-6.4.1 Android example | ad-baner-without-googleadmobadssdkandroid-6-4-1-android-example


First: AdView is in XML file

<com.google.android.gms.ads.AdView
    xmlns:ads="//schemas.android.com/apk/res-auto"
    android:id="@+id/adView"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    ads:adUnitId="MY_AD_UNIT_ID"
    ads:adSize="BANNER"/>

// onResume
AdView adView = (AdView)this.findViewById(R.id.adView);
AdRequest adRequest = new AdRequest.Builder()
    .addTestDevice(AdRequest.DEVICE_ID_EMULATOR)
    .addTestDevice("TEST_DEVICE_ID")
    .build();
adView.loadAd(adRequest);




Second: Using AdView in Fragment with LinearLayout
Resolve error in ADT Graphical layout editor:
The following classes could not be instantiated:
- com.google.android.gms.ads.AdView

// layout in xml file
    <LinearLayout
        android:id="@+id/layout"
              android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

// java class with fragment in Fragment class or in Activity class
private static AdView adView;
        @Override
		public void onResume(){  
                super.onResume();
                 try {
                	 // in xml is empty layout
					adView = new AdView(getActivity());
					adView.setAdUnitId("ca-app-pub-626/638103xxxxxxx");
					adView.setAdSize(AdSize.BANNER);  
					
                	                LinearLayout layout = (LinearLayout)getView() .findViewById(R.id.layout);
					layout.addView(adView);
					
					AdRequest adRequest = new AdRequest.Builder().build();   
					adView.loadAd(adRequest);

				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
        }


More about:
https://developers.google.com/mobile-ads-sdk/docs/admob/android/play-migration?hl=it
55

How update View TextView with timer Android runnable example | how-update-view-textview-with-timer-android-runnable-example


Update TextView by runnable. Handler, runnable, timer Android example.


public class TimerActivity extends Activity {
TextView hTextView;
Button hButton, hButtonStop;
private Handler mHandler = new Handler();
private int nCounter = 0;
@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        hTextView = (TextView)findViewById(R.id.idTextView);
        hButton = (Button)findViewById(R.id.idButton);
        hButton.setOnClickListener(mButtonStartListener);
        hButtonStop = (Button)findViewById(R.id.idButtonStop);
        hButtonStop.setOnClickListener(mButtonStopListener);
    } // end onCreate

View.OnClickListener mButtonStartListener = new OnClickListener() {
	public void onClick(View v) {
		try {
			mHandler.removeCallbacks(hMyTimeTask);
         //        Parameters
         //        r  The Runnable that will be executed. 
         //        delayMillis  The delay (in milliseconds) until the Runnable will be executed. 
                       mHandler.postDelayed(hMyTimeTask, 1000); // delay 1 second
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
};


private Runnable hMyTimeTask = new Runnable() {
	   public void run() {
		   nCounter++;
	    	   hTextView.setText("Hallo from thread counter: " + nCounter);
	   }
	}; 
/**
 * 
 */
    View.OnClickListener mButtonStopListener = new OnClickListener() {
    	public void onClick(View v) {
    		 mHandler.removeCallbacks(hMyTimeTask);
    		
    	}
    };
}





main.xml



<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="//schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView  
	android:id="@+id/idTextView"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/hello"
    />
<Button android:text="Button" 
android:id="@+id/idButton" 
android:layout_width="wrap_content" 
android:layout_height="wrap_content"></Button>
 
 <Button android:layout_width="wrap_content" 
 android:layout_height="wrap_content" 
 android:id="@+id/idButtonStop" 
 android:text="Stop"></Button> 
    
    
</LinearLayout>






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