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Get Screen Size Pixels per Inch Android example


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The exact physical pixels per inch of the screen
Get size of pixel
Get DPI
Get count of pixels per inch

        float mXDpi;
        float mYDpi;
           DisplayMetrics metrics = new DisplayMetrics();
            getWindowManager().getDefaultDisplay().getMetrics(metrics);
            mXDpi = metrics.xdpi; // The exact physical pixels per inch of the screen in the X dimension. 
            mYDpi = metrics.ydpi;
          float  mMetersToPixelsX = mXDpi / 0.0254f; // 1 inch == 0.0254 metre
          float  mMetersToPixelsY = mYDpi / 0.0254f;



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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);
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>




270

How to Add Home Screen Widgets on Your Android Phone | how-to-add-home-screen-widgets-on-your-android-phone


Long press by finger on screen
From dialogue select Widgets
Select your widget
Put your widget on the screen

Video tutorial - to add home screen widgets - Android 2.1

69

Timer task TimerTask run cancel Android example | timer-task-timertask-run-cancel-android-example


Update TextView from TimerTask, Handler, schedule, run, cancel TimerTask, Android example

public class TimerActivity extends Activity {
	TimerTask mTimerTask;
	final Handler handler = new Handler();
	Timer t = new Timer();	
TextView hTextView;
TableRow hTableRow;
Button hButton, hButtonStop;


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) {
		doTimerTask();
    }
};



	
	View.OnClickListener mButtonStopListener = new OnClickListener() {
    	public void onClick(View v) {
    		stopTask();
    		
    	}
    };
    
    
    public void doTimerTask(){

    	mTimerTask = new TimerTask() {
    	        public void run() {
    	                handler.post(new Runnable() {
    	                        public void run() {
    	                        	nCounter++;
                                        // update TextView
    	                        	hTextView.setText("Timer: " + nCounter);

    	                        	Log.d("TIMER", "TimerTask run");
    	                        }
    	               });
    	        }};

            // public void schedule (TimerTask task, long delay, long period) 
    	    t.schedule(mTimerTask, 500, 3000);  // 

    	 }

    	  public void stopTask(){

    	   if(mTimerTask!=null){
    	      hTextView.setText("Timer canceled: " + nCounter);

    	      Log.d("TIMER", "timer canceled");
    	      mTimerTask.cancel();
    	 }
    
    }    
}


390

Android runtime change switch Activity theme | android-runtime-change-switch-activity-theme



static boolean mbThemeLight = false;

 @Override
    public void onCreate(Bundle savedInstanceState) {
         if(mbThemeLight)
        setTheme(android.R.style.Theme_Light);
        super.onCreate(savedInstanceState);
        // bla bla bla..........
    }

private void switchTheme(){
 mbThemeLight = true;
 this.recreate();
}


Editace: 2013-12-09 13:06:15
Počet článků v kategorii: 397
Url:get-screen-pixels-android-example

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