Delete Canvas - Fill Canvas Android example
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Fill the entire canvas with the specified color.
@Override
public void onDraw(Canvas canvas) {
canvas.drawColor(Color.GREEN);
}
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Problemi is in e.getMessage() what can return null and Log.e (String tag, String msg) will throws an new exception !!!!
Problem and solution:
LogCat:
Or you can using this code:
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)
The Labeled continue statement as goto Java example.
public class MainClass {
public static void main(String[] arg) {
String[] arrayOfString = { "Hello", "people", "hello", "world!" };
OuterLoop: for (int e = 0; e < 4; e++) {
for (int i = 0; i < arrayOfString.length; i++) {
if (arrayOfString[i].equals("hello"))
continue OuterLoop;
System.out.println(arrayOfString[i]);
}
}
}
}
/*
Hello
people
Hello
people
Hello
people
Hello
people
*/
// Context instead Activity as a parameter
@Override
public void onAttach(Context context) {
super.onAttach(context);
Activity a;
if (context instanceof Activity){
a=(Activity) context;
}
}
OnNoteClickedListener listener;
/* old emxample of usage
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
listener = (OnNoteClickedListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnNoteClickedListener");
}
}
*/
// new version of code
@Override
public void onAttach(Context context) {
super.onAttach(context);
Activity a;
if (context instanceof Activity){
a=(Activity) context;
try {
listener = (OnNoteClickedListener) a;
} catch (ClassCastException e) {
throw new ClassCastException(a.toString()
+ " must implement OnNoteClickedListener");
}
}
}
Switch statement with numbers and array of strings Java example.
Possible:
public class MainClass {
public static void main(String[] arg) {
String[] arrayOfString = { "One", "Two", "Three", "Four" };
int i = 2;
switch (i) {
case 1: {
System.out.println(arrayOfString[i]);
break;
}
case 2: {
System.out.println(arrayOfString[i]);
break;
}
case 3: {
System.out.println(arrayOfString[i]);
break;
}
default: {
System.out.println("Enter a valid value.");
}
} // END of switch
}
}
/*
* Three
*/
Possible:
case 1:
System.out.println(arrayOfString[i]);
break;
// i love this notation
case 1:{
System.out.println(arrayOfString[i]);
}break;
case 1:{
System.out.println(arrayOfString[i]);
break;
}
If you try function for checking internet connection you can disable internet on the emulator:
Settings - Wireless and networks - Mobile networks - Data enabled (checked - unchecked )
Settings - Wireless and networks - Mobile networks - Data enabled (checked - unchecked )
public boolean isNetworkAvailable() {
ConnectivityManager cm = (ConnectivityManager)
getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = cm.getActiveNetworkInfo();
if (networkInfo != null && networkInfo.isConnected()) {
return true;
}
return false;
}
Editace: 2013-12-09 13:04:00
Počet článků v kategorii: 397
Url:delete-canvas-fill-canvas-android-example
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