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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Další témata ....(Topics)
C:\documents\workspace\.metadata\.plugins\org.eclipse.core.runtime\.settings\org.eclipse.jdt.ui.prefs
BufferedReader , FileReader, StringBuilder , readLine, close Java example
Android example
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();
}
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.
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.
AlertDialog like MessageBox by WinApi:
If error: Unable to add window -- token null is not for an application
try change get Context.
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();
// 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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