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android.app.Application cannot be cast to android.app.Activity


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If you using Context as parameter of function try this solution:

public class MyActivity extends Activity {
// bla bla bla .......
//error 
myFc( getapplicationcontext());
// OK
myFc(MyActivity.this);

397LW NO topic_id




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Where Eclipse stored Settings and Templates Java Code | where-eclipse-stored-templates-java-code



C:\documents\workspace\.metadata\.plugins\org.eclipse.core.runtime\.settings\org.eclipse.jdt.ui.prefs
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File open read to StringBuilder close Java example | file-open-read-to-stringbuilder-close-java-example


BufferedReader , FileReader, StringBuilder , readLine, close Java example

Android example

String MYFILE = "my_file";
FileInputStream fis = openFileInput(MYFILE);
	int c; String sText = "";
	while((c=fis.read())!=-1)
	{

		sText += (char)c; // convert int to char
	 }
	fis.close();						



Java example

try {
	    BufferedReader in = new BufferedReader(new FileReader("myfile.txt"));
	    StringBuilder strBuilder = new StringBuilder();
	    String str;
	    while ((str = in.readLine()) != null) {
	       strBuilder.append(str);
	    }
	    in.close();
	} catch (IOException e) {
		e.toString();
	}

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


Terms Screen size, density, density independent pixel, resolution as a picture - pictogram.
mobile-phone-screen-resolution-terms

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.

 

 
116

AlertDialog - MessageBox - Alert - Toast - Android sample | alertdialog-like-messagebox-android-sample


AlertDialog like MessageBox by WinApi:
If error: Unable to add window -- token null is not for an application
try change get Context.

// you can put this text into some function body or case in switch statement
                new AlertDialog.Builder(this)
                    .setMessage("Hello boys!!!")
                    .setPositiveButton("OK", null)
                    .show();



Context context = getApplicationContext();
	AlertDialog.Builder builder = new AlertDialog.Builder(context);
	builder.setTitle("Select font size");
	final CharSequence[] chsSize= { "Small", "Medium", "Large"};
	builder.setSingleChoiceItems(chsSize, 0 /*sel.item*/, 
	new DialogInterface.OnClickListener() {
 	    public void onClick(DialogInterface dialog, int item) {
	    		 Toast.makeText(context, "Hello from dialog!!!", Toast.LENGTH_SHORT).show();
	        dialog.dismiss();
	    }
	});
	AlertDialog alert = builder.create();
	alert.show();
    
283

Get Set Screen Orientation Android Code | get-set-screen-orientation-android-code



// in AndroidManifest.xml
<Activity
 android:screenOrientation="portrait" // or landscape

// in MyActivity.java
boolean mbOrientacionLandscape = false;
int nOrientation =	getResources().getConfiguration().orientation;
if(mbOrientacionLandscape==true){
	 getResources().getConfiguration();
	if(nOrientation != Configuration.ORIENTATION_LANDSCAPE)
	setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
	
}
else{
	if(nOrientation != Configuration.ORIENTATION_PORTRAIT)
	setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
}



Editace: 2015-11-28 18:55:09
Počet článků v kategorii: 397
Url:android-app-application-cannot-be-cast-to-android-app-activity

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