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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;
    public void onCreate(Bundle savedInstanceState) {
        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)


No resource found that matches the given name Eclipse Android xml file | no-resource-found-that-matches-the-given-name-eclipse-android-xml-file

No resource found that matches the given name - error examples.
Exist resource file?
Is code written correctly?

// No resource found that matches the given name (at id with value @id/myButton).
 android:id="@id/myButton" // invalid id notation
 android:id="@+id/myButton" // correct

 // No resource found that matches the given name 
// (at icon with value @drawable/icons).
// exist file icons in res/drawable folder?
<application android:icon="@drawable/icons" 

//No resource found that matches the given name 
//(at theme with value @style/MyThem).
<activity android:name=".Main"

// Exist style MyThem  in styles.xml ?  No only MyTheme
<style name="MyTheme" parent="android:Theme">
        <item name="android:windowTitleSize">50px</item>

// exist file my_background in folder drawable ?
android:background="@drawable/my_background" // 

// no resource found that matches the given name(at "label" with value "@string/app_name")
// have you the string resource defined in res/values/strings.xml ?
<string name="app_name">"My App"</string>


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

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

public class ApokusActivity extends Activity {
	protected void onCreate(Bundle savedInstanceState) {
		setContentView(new SampleView(this));

	private static class SampleView extends View {

		public SampleView(Context context) {

		protected void onDraw(Canvas canvas) {
			Paint paint = new Paint();

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



Conversion to Dalvik format failed with error 1 | conversion-to-dalvik-format-failed-with-error-1

java.lang.IllegalArgumentException: already added: Lcz/okhelp/MyMathClass;

First try this solution!!!!!
Select your project in project tree and go to the Eclipse menu Project » Clean » Clean projects selected below » select your project and click OK.

If you create *.apk package with proguard sometimes you must back up the project, delete project, and create new project if you are unable to create *.apk file.

Check your AndroidManifest.xml if all Activity is correctly inserted. If you add a library project to Main project you have to insert Activity from library to Main project AndroidManifest.xml

Problem with the library.
I deleted library project from project tree and again put the _library project into the main project. This problem was resolved.
1.)Go to Project » Properties » Java Build Path » Libraries and remove (your projects) click OK.
2.)Go to Project » Clean » Clean projects selected below » select your project and click OK.
3.)Add again your LIBRARY project to your MAIN project Project » Properties » Java Build Path » Libraries.
See image below.

Problem with a *.apk file
If you create signed *.apk, you have to delete previous *.apk from your PC folder.



Screen size density independent pixel resolution | screen-size-density-independent-pixel-resolution

Terms Screen size, density, density independent pixel, resolution as a picture - pictogram.

Test your knowledge
Q: How to find out the phone screen size?
A: (By length of display diagonale in inch -  Not to measure a diagonal of device!!!)

Q: What resolution has 720 x 1280 display?
A: (921600 pixels)

Q: What does it mean "240 dpi" screen density?
A: (Display have density 240 x 240  dots - "Tri-color LED etc." - per every physical (real) square inch. If you have icon 240x240 pixels, this will just occupy an area of one square inch on the display.)

Q: Phone have screen density 240 dpi. Image for 160 dpi screen density have size 128x 128 pixels. What will be the size of the image for 240 dpi screen density?
A: (Calculate the virtual pixels size.   128 * (240/160)  =  192.  You have to resize image to new size 192 x 192 physical pixels and put into folder drawable-hdpi (high) ~240dpi  for phone with screen density 240 dpi. ) or use density independend pixels 128dp x 128dp.



Emulator window was out of view and was recentred - Android emulator warning | emulator-window-was-out-of-view-and-was-recentred-android-emulator-warning

Emulator window was out of view and was recentred
Emulator] WARNING: Data partition already in use. Changes will not persist!
Emulator] WARNING: SD Card image already in use: C:\Documents and Settings\user_name\.android\avd\hvga21_up1_7.avd/sdcard.img
Emulator] WARNING: Cache partition already in use. Changes will not persist!

Basic step
Try restart Eclipse if using from menu File->Restart

Other solutions

Solution 1: try restart ADB server

Solution 2:

Delete Run Configuration


Solution 3:
Try delete:

c:\Documents and Settings\user_name\.android\avd\my_avd.avd\cache.img
c:\Documents and Settings\user_name\.android\avd\my_avd.avd\userdata-qemu.img

Try solution 4:
Eclipse menu select Window->Preferences->Android

Windows 32

FROM: C:\Program Files\Android\android-sdk
TO: C:\PROGRA~1\Android\android-sdk

Windows 64

FROM: C:\Program Files (x86)\Android\android-sdk
TO: C:\PROGRA~2\Android\android-sdk

Editace: 2011-09-29 20:44:21
Počet článků v kategorii: 397

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