Get Context Java Android example
getContext() getApplicationContext() method Java Android example source
Context myContext_1 = ThisClassName.this; // to open a Dialog
Context myContext_2 = getContext();
Context myContext_3 = this.getContext();
Context myContext_4 = this;
Context myContext_5 = this.getApplicationContext ();
OnClickListener getImageBtnOnClick = new OnClickListener() {
public void onClick(View view) {
Context context = view.getContext();
}
};
// Toast
Toast.makeText(getApplicationContext(), "Context == getApplicationContext "
, Toast.LENGTH_SHORT).show();
// store Context in public class
public class MyActivity extends Activity {
public static Context myCnt = null;
...
protected void onCreate(Bundle icicle) {
...
myCnt = this;
MyStorage.setContext(myCnt);
// or
// MyStorage.setContext(this);
// cntxFromStorage == this
Context cntxFromStorage = MyStorage.getContext();
...
};
};
public class MyStorage
{
private static Context cntStorageContext = null;
public static Context getContext() {
return cntStorageContext;
}
public static void setContext(Context context) {
MyStorage.cntStorageContext = context;
}
};
class DataBaseHelper extends SQLiteOpenHelper {
// get MyActivity context
Context cnt = MyStorage.getContext();
}
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Další témata ....(Topics)
Check
- is sett debug mode on device?
- enabled debugging over USB?
- is device right connected?
- have you downloaded and instaled drivers for your device on PC?
- For Windows //developer.android.com/sdk/win-usb.html
- try disconnect and connect USB cable
- try do restart Android Studio
UNEXPECTED TOP-LEVEL EXCEPTION:
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.
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.
How to change the image dynamically in ImageView and button setOnClickListener Android sample.
Main.java
main.xml
Put into res/drawable this pictures:
Main.java
ipackage cz.okhelp.my_game;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
public class Main extends Activity {
private ImageView hImageViewSemafor;
private Button hButton;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
hImageViewSemafor = (ImageView)findViewById(R.id.idImageViewSemafor);
hButton = (Button) findViewById(R.id.idBtnChangeImage);
hButton.setOnClickListener(mButtonChangeImageListener);
}
View.OnClickListener mButtonChangeImageListener = new OnClickListener() {
public void onClick(View v) {
// setImageResource will change image in ImageView
hImageViewSemafor.setImageResource(R.drawable.semafor_green);
}
};
}
main.xml
Put into res/drawable this pictures:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="//schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<ImageView
android:src="@drawable/semafor_red"
android:id="@+id/idImageViewSemafor"
android:background="#66FFFFFF"
android:adjustViewBounds="true"
android:maxWidth="47dip"
android:maxHeight="91dip"
android:padding="10dip"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
Map<Float,String> linkedHashMap = new LinkedHashMap<Float, String>();
linkedHashMap.put(14.f, "text");
linkedHashMap.put(13.f, "text");
linkedHashMap.put(10.f, "text");
linkedHashMap.put(11.f, "text");
linkedHashMap.put(2.f, "text");
linkedHashMap.put(3.f, "text");
linkedHashMap.put(1.f, "text");
linkedHashMap.put(7.f, "text");
linkedHashMap.put(23.f, "text");
for (Entry<Float,String> entry : linkedHashMap.entrySet()) {
System.out.println(entry.getKey());
}
14.0
13.0
10.0
11.0
2.0
3.0
1.0
7.0
23.0
Map<Float,String> hashMap = new HashMap<Float, String>();
hashMap.put(14.f, "text");
hashMap.put(13.f, "text");
hashMap.put(10.f, "text");
hashMap.put(11.f, "text");
hashMap.put(2.f, "text");
hashMap.put(3.f, "text");
hashMap.put(1.f, "text");
hashMap.put(7.f, "text");
hashMap.put(23.f, "text");
for (Entry<Float,String> entry : hashMap.entrySet()) {
System.out.println(entry.getKey());
}
// key :
1.0
14.0
3.0
13.0
2.0
7.0
11.0
23.0
10.0
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);
}
}
Editace: 2011-10-15 08:31:19
Počet článků v kategorii: 396
Url:get-context-java-android-example
