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Leap year date time Java Android example



GregorianCalendar cal = new GregorianCalendar(); Boolean b = cal.isLeapYear(2012); // true, Android example.



public class MainActivity extends Activity {
TextView txtV;
	Context cntx;
	
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        txtV = (TextView)findViewById(R.id.idLabel);
        cntx = this;
        StringBuilder strBuild = new StringBuilder();
        
         GregorianCalendar cal = new GregorianCalendar();
         Boolean b = cal.isLeapYear(2012); // true
         strBuild.append("Is leap year 2012? " + b + "

"); b = cal.isLeapYear(2014); // false strBuild.append("Is leap year 2014? " + b + "
"); txtV.setText(strBuild); } }

397LW NO topic_id



Další témata ....(Topics)


134

Draw Oval Android basic example | draw-oval-android-basic-example


drawOval(), setStrokeWidth(), setStyle()


public class MainActivity extends Activity {
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(new SampleView(this));
	}

	private static class SampleView extends View {

		// CONSTRUCTOR
		public SampleView(Context context) {
			super(context);
			setFocusable(true);

		}

		@Override
		protected void onDraw(Canvas canvas) {

			canvas.drawColor(Color.CYAN);
			Paint p = new Paint();
			// smooths
			p.setAntiAlias(true);
			p.setColor(Color.RED);
			p.setStyle(Paint.Style.STROKE); 
			p.setStrokeWidth(4.5f);
			// opacity
			//p.setAlpha(0x80); //
 
			canvas.drawOval(new RectF(50, 50, 20, 40), p);;
		}

	}
}
138

Draw text drawText Android basic example | draw-text-drawtext-android-basic-example


drawText(), setColor(), setTextSize(), setTextAlign()

public class ApokusActivity extends Activity {
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(new SampleView(this));
	}

	private static class SampleView extends View {

		// CONSTRUCTOR
		public SampleView(Context context) {
			super(context);
			setFocusable(true);

		}
		@Override
		protected void onDraw(Canvas canvas) {
			Paint paint = new Paint();
			
            paint.setColor(Color.YELLOW);
            paint.setTextSize(60);
            //paint.setTextAlign(Paint.Align.CENTER);

            canvas.drawText("Hello world!", 0, 50, paint);
		}

	}
}

105

How to make a horizontal line in Android application example code | how-to-make-a-horizontal-line-in-android-application-example-code


In html is horizontal line a tag br. In Android source code you can use a View as xml example bellow.

<View
android:layout_width="fill_parent"
android:layout_height="4dip"
android:background="#ffffff"
android:paddingBottom="10dip"
/>
206

java.lang.NullPointerException: println needs a message | java-lang-nullpointerexception-println-needs-a-message


Problemi is in e.getMessage() what can return null and Log.e (String tag, String msg) will throws an new exception !!!!
Problem and solution:

      	try {
      		int [] i = {1};
      		int z = i[5];
      	} catch (ArrayIndexOutOfBoundsException e) {
      		String s = e.toString(); // s == java.lang.ArrayIndexOutOfBoundsException
                // try to testing String s for null value
      		if(s != null)
      		 Log.e("bla", s);
      		else 
      		 Log.e("bla", "My error text 1");
      		
      		String s2 = e.getMessage(); // s2 == null !!!!!!!
                // you need to testing String s2 for null value , or you get FATAL EXCEPTION: main
                // and application will be crashed
       		String s2 = e.getMessage(); // s2 == null !!!!!!!
      		if(s2 != null)
      		 Log.e("bla2", e.getMessage());
      		else 
      		 Log.e("bla2", "My error text 2");
     		
                // this is OK
      		e.printStackTrace();
      	}


LogCat:

E/bla(855): java.lang.ArrayIndexOutOfBoundsException

 E/bla2(855): My error text 2

 W/System.err(855): java.lang.ArrayIndexOutOfBoundsException
 W/System.err(855): 	at cz.okhelp.motion._MotionActivity.onTouchEvent(_MotionActivity.java:54)
 W/System.err(855): 	at android.app.Activity.dispatchTouchEvent(Activity.java:2099)
 W/System.err(855): 	at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1675)
 W/System.err(855): 	at android.view.ViewRoot.deliverPointerEvent(ViewRoot.java:2194)
 W/System.err(855): 	at android.view.ViewRoot.handleMessage(ViewRoot.java:1878)
 W/System.err(855): 	at android.os.Handler.dispatchMessage(Handler.java:99)
 W/System.err(855): 	at android.os.Looper.loop(Looper.java:123)
 W/System.err(855): 	at android.app.ActivityThread.main(ActivityThread.java:3683)
 W/System.err(855): 	at java.lang.reflect.Method.invokeNative(Native Method)
 W/System.err(855): 	at java.lang.reflect.Method.invoke(Method.java:507)
 W/System.err(855): 	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
 W/System.err(855): 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
 W/System.err(855): 	at dalvik.system.NativeStart.main(Native Method)




Or you can using this code:

      	try {
      		int [] i = {1};
      		int z = i[5];
      	} catch (Exception e) {
      		
      		
      		StringBuilder sb = new  StringBuilder().append(e.getClass().getSimpleName()); 
          if  (e.getMessage() != null) { 
              sb.append("

"); sb.append(e.getMessage()); } Log.e("err", sb.toString()); // E/err(336): ArrayIndexOutOfBoundsException // this code write out all message Log.e("myError", "methodName", e); } // E/myError(371): methodName // E/myError(371): java.lang.ArrayIndexOutOfBoundsException // E/myError(371): at cz.okhelp.motion._MotionActivity.onTouchEvent(_MotionActivity.java:54) // E/myError(371): at android.app.Activity.dispatchTouchEvent(Activity.java:2099) // E/myError(371): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1675) // E/myError(371): at android.view.ViewRoot.deliverPointerEvent(ViewRoot.java:2194) // E/myError(371): at android.view.ViewRoot.handleMessage(ViewRoot.java:1878) // E/myError(371): at android.os.Handler.dispatchMessage(Handler.java:99) // E/myError(371): at android.os.Looper.loop(Looper.java:123) // E/myError(371): at android.app.ActivityThread.main(ActivityThread.java:3683) // E/myError(371): at java.lang.reflect.Method.invokeNative(Native Method) // E/myError(371): at java.lang.reflect.Method.invoke(Method.java:507) // E/myError(371): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) // E/myError(371): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) // E/myError(371): at dalvik.system.NativeStart.main(Native Method)

283

addPreferencesFromResource Deprecated Android Code Warning | addpreferencesfromresource-deprecated-android-code-warning


Put extends PreferenceFragment API level 11 instead PreferenceActivity

public class SettingsActivity extends PreferenceFragment {
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      addPreferencesFromResource(R.xml.preferences);
  }
}

// or insert suppresswarning
public class SettingsActivity extends PreferenceActivity {
  @SuppressWarnings("deprecation")
	@Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      addPreferencesFromResource(R.xml.preferences);
  }
}



Editace Jana Žákovská : 2011-09-29 20:44:21
Počet článků v kategorii: 397
Url:leap-year-date-time-java-android-example
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