Android :: Why Should A Variable In Static Method Be Declared As Final In Java
Sep 15, 2010
I am having a static method .In the method when I decalare a variable , it was showing an error in eclipse saying that the variable should be decalared as final.
Can I know the reason for this , y should a variable in a static method be declared as final? I am writng an Android application where I should pass as an argument current Context of that application. So, when I pass the current context to the method and trying to copy it in a local variable , I am getting this error saying that the variable should be declared as final.
My method is like this:
CODE:.............
Error is showing at line where Context myctx=ctx; is declared and asking me to declare it as final.
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Sep 15, 2010
Why should a static method in java accept only final or non final variables within its method, but not static?
For example I have the following method:
CODE:.................
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Apr 15, 2010
I want to refer to a static Java variable in my styles.xml, is that possible? Here's a pseudo-xml example:
<style name="Artwork">
<item name="android:background">@drawable/border_{Constants.MY_COLOR}</item>
</style>
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Dec 22, 2009
In my Android app, I need to call a non static java method from C/C++. But i get a blunt crash when i do it using GetMethodID/CallVoidMethod()1 methods.
I have done like this:
1. Register the method using GetMethodID() as follows (mine is a cpp file): jmethodID xyz = (env)->GetMethodID( cls, "showxyz", "()V");
2. And I call this method as follows: env->CallVoidMethod(cls, xyz);
3. In java, my showxyz() is defined this way(this basically enables a button which was disabled) void showxyz() {findViewById(R.id.btnPass).setEnabled(true);}
And this crashes.
But I have been using this method of calling Java funcs from C using a set of GetStaticMethodID/CallStaticVoidMethod()(for nonstatic methods) and that works always.
But in this case, I have to call a non-static method and i get a crash.
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Mar 30, 2010
i want to display a msg to the user (msg box or Toast) when exception happend in a static SQLite Database class that i use. the problem is that i cant call a non static method in a static class , how can i handle this. this is the class
private static SQLiteDatabase getDatabase(Context aContext) {
and i want to add something like this in the class when exception happen but context generates the problem of reference to non static in static class.
Context context = getApplicationContext();
CharSequence text = "Hello toast!";
int duration = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(context, text, duration);
toast.show();
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Feb 7, 2010
I'm having some issues with the old "Cannot make a static reference to a non-static method" error in my Android program. I am creating a sand falling game (similar to the Powder Game) and I created a class called Control to create a Control Bar at the bottom of the screen with a slider for brush size (that works fine) and a button to pop up a Dialog to allow users to pick the selected element. However, when I call DemoActivity.showDialog(2) from my code, it gives the static reference to non-static error (DemoActivity is the main activity of my application). I also tried changing it to just Activity.showDialog(2), but I got exactly the same error!
Here's my code:
CODE:................
I fixed it by adding the following to my Control.java code:
CODE:..........
And then calling control.setActivity(this); from my onResume section of DemoActivity.java!
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May 26, 2010
I am modifying the source code here: http://thinkandroid.wordpress.com/2009/12/30/getting-response-body-of-httpresponse/
I get this error:
code:.............
This error is line 13 on the second box.
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Apr 1, 2009
I have noticed in my application(s) that after a call to Activity.finish() that the static variables that I declared in my classes still hold the values that they were changed to during the activity's life cycle. Upon the re-launch of the activity, the program does not re-instantiate the variables as declared or set them to the default java behavior. Is there something that I can do to cause this to happen, other than re-setting every static variable in my application?
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Aug 26, 2010
I want to clear variable value when will i close activity.
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Jul 16, 2009
I have some static variables and some registerListeners. Do i need to release them all and remove these listeners?
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Aug 31, 2010
I have used some static variable in my application, i want to clear static variable value when will i close my application.anybody know please give solution for that.
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Mar 16, 2009
I'm trying to call a java method from javascript using addJavascriptInterface(); but seems does not work, it always display "failure"; java code...
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Jun 23, 2009
My application crashes after I try to use the static Bitmap createBitmap method to get a mutable bitmap in order to fill it later with data.
If I only create one 1024x1024 the application works just fine, but when I try to load the same image more than once (first making my object null in each round) my application crashes on my third or fourth try.
CODE:..........................
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May 7, 2010
I'm working on an Android application that has several Activities. In it I have a class with several static methods. I would like to be able to call these methods from the different Activities. I'm using the static methods to load data from an xml file via a XmlResourceParser. To create a XmlResourceParser requires a call on the Application Context. So my question is, what is the best way to get a reference to the Application Context into the static methods? Have each Activity get it and pass it in? Store it somehow in a global variable?
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Aug 21, 2010
I have a broadcast receiver that needs to notify a service that it has received a text message. The only way to do this (as far as I know) is a static method. But the method that is notified need access to the application's preferences.
Every method I have tried says that it cannot be accessed from a static method. So how do I access preferences from a static method?
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Sep 29, 2010
When programming for Android sometimes you have to use static methods. But when you try to acces you resources in a static method with getString(R.string.text) you'll get an error. Making it static doesn't works. Does anyone knows a good way around this because the resource files in Android are very helpfull for creating things in different languages or making changes to a text.
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Mar 27, 2009
I wish to get the environment variable which is set by a daemon in native but failed. Some details: in the daemon, which is started by root setenv("MY_NAME", name, 1); in java code, which is started by system String name = System.getenv("MY_NAME);
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Nov 24, 2010
I'm having a big issue with a static HTTPS connection method. Every second request fails and HttpsUrlConnection.getResponseCode() returns -1. So every second call works well, returning data as expected.
It's the method of a static class I'm using in different corners of my application. I would guess there is anything I don't clean up correctly when the method returns the first time and that whatever causes a problem might get destroyed through a second call of the method. But I'm having a hard time finding any clues.
I'm currently using this class to talk to hosts with invalid SSL certificates. Not going to use this in the final version of the app, but right now I need to save money. ;)
CODE:.......................
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Nov 5, 2010
I'm writing an android app that requires binding a JSON object into a domain entity with the keys from the JSON as instance variables. Since there are several domain entities, each with different instance variables that the JSON needs to bind to in the app, i'd like to write a method such as ths following: Loop through all the instance variables from the domain if a key exists in the JSON with the name of the instance variable, take the value for this key from the JSON and set the Domain's instance variable with this key name equal to this value. The reason i'm interested in the doing the binding from the class to the JSON is because if the JSON changes for some reason, I don't want it to break the app when the instance variable doesn't exist in the app's domain for a specific JSON key. Code...
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Oct 18, 2010
I've been trying to call a non-static method, located in my main application Class, from the Preferences Class. Because the method I call is not static, I instantiate the main class and then try to call the specific method I want but it's force closing.
Preferences.class (from where I call the method):
Preference sorted = (Preference) findPreference("sortPref");
sorted.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
public boolean onPreferenceChange(Preference preference, Object newValue) {
Object d = new Dmarks();
((Dmarks) d).queryBookmarks();
return true;
}});
the Dmarks.class method I call:
public void queryBookmarks() {
Toast.makeText(context, Toast.LENGTH_LONG).show();
//context is not null and the Toast is working if I call it from Dmarks.class }
The Logcat:
E/AndroidRuntime(11718): FATAL EXCEPTION: main
E/AndroidRuntime(11718): java.lang.NullPointerException
E/AndroidRuntime(11718):
at android.content.ContextWrapper.getContentReso
lver(ContextWrapper.java:90)
E/AndroidRuntime(11718):
at android.app.Activity.managedQuery(Activity.ja
va:1520)
E/AndroidRuntime(11718):
at com.droidil.droidmarks.Dmarks.queryBookmarks(
Dmarks.java:101)
E/AndroidRuntime(11718):
at com.droidil.droidmarks.Preferences$2.onPrefer
enceChange(Preferences.java:47)
E/AndroidRuntime(11718):
at android.preference.Preference.callChangeListe
ner(Preference.java:756)
E/AndroidRuntime(11718):
at android.preference.ListPreference.onDialogClo
sed(ListPreference.java:219)
E/AndroidRuntime(11718):
at android.preference.DialogPreference.onDismiss
(DialogPreference.java:384)
E/AndroidRuntime(11718):
at android.app.Dialog$ListenersHandler.handleMes
sage(Dialog.java:1047)
E/AndroidRuntime(11718):
at android.os.Handler.dispatchMessage(Handler.ja
va:99)
E/AndroidRuntime(11718):
at android.os.Looper.loop(Looper.java:123)
E/AndroidRuntime(11718):
at android.app.ActivityThread.main(ActivityThrea
d.java:4627)
E/AndroidRuntime(11718):
at java.lang.reflect.Method.invokeNative(Native
Method)
E/AndroidRuntime(11718):
at java.lang.reflect.Method.invoke(Method.java:5
21)
E/AndroidRuntime(11718):
at com.android.internal.os.ZygoteInit$MethodAndA
rgsCaller.run(ZygoteInit.java:868)
E/AndroidRuntime(11718):
at com.android.internal.os.ZygoteInit.main(Zygot
eInit.java:626)
E/AndroidRuntime(11718):
at dalvik.system.NativeStart.main(Native Method)
D/dalvikvm(11718): GC_FOR_MALLOC freed 4248 objects / 282248 bytes in 40ms
W/ActivityManager( 244): Force finishing activity com.droidil.droidmarks/.Preferences
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Jul 8, 2010
I have class A, with methods foo and bar, that are implemented by A1 and A2. The functionality in both A1 and A2 is the same. In other words:
public class A {
public int foo() { return 0; };
public int bar() { return 1; };
} class A1 extends A {
public int AnotherFooFunction() { return foo();
} public int AnotherBarFunction() { return bar();
} } class A2 extends A {
public int AnotherFooFunction() { return foo();
} public int AnotherBarFunction() { return bar();
} }
Is it better to keep the code in this fashion, or to swap out those virtual methods as static methods? (In Java, everything non-final/non-private is considered virtual, right?) According to the Designing for Performance section in the Android Developer Docs, I should swap out these virtual methods for static ones. So the above becomes:
public class A {
public int foo() { return 0; };
public int bar() { return 1; };
} class A1 extends A {
public int AnotherFooFunction() { return A.foo();
} public int AnotherBarFunction() { return A.bar();
} class A2 extends A {
public int AnotherFooFunction() { return A.foo();
} public int AnotherBarFunction() { return A.bar();
} }
Is this how it "ought" to be? I fully realize that I may be misinterpreting this paragraph in the docs.
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Apr 27, 2010
I have some C++ code that I want to make into a static lib for use with Java on the Android platform. Can anyone point me to a resource that tells me how to do this? I am completely new to Java and Android.
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Feb 11, 2009
I'm having some problems porting a Java application to work in Android platform. I detected an incompatibility problem between java sun and Adroid sdk in java.lang.Class. I oberved that: public Field[] getFields() Returns an array containing Field objects describing all fields which are defined. That's array is sorted as attributes are declared in the main Class in sun jdk. For example, next Class is defined as: public class Example { public boolean stop; public int atr1; public String name; ....
}
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Aug 31, 2010
I m doing some task with following code,
I want to access inner class variable from outer class method.
class Outer extends Activity
{private Handler mHandler = new Handler();
StopTheThread()
{mHandler.removeCallbacks(mUpdateTimeTask);//
This is the what I want to do:
} class Inner
{ final Runnable mUpdateTask = new = new Runnable() {
public void run() {
//Some Code Goes Here
} };
InnerClassMethod()
{ mHandler.removeCallbacks(mUpdateTimeTask);//
This statement working fine here. Here mUpdateTask is inner class variable which is not accessible from outer class.
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Nov 5, 2010
I am working on an Android project that uses classes and methods from a seperate JAR file I am also creating, and the issue is with a specific util class called XpathUtil that is throwing a VerifyError every time I try calling one of its static methods. Here is how my XpathUtil class looks like:........................
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Nov 19, 2010
I want to use somthing like: MyLogger.e("MyApp","I have an error.");
In a cross-plattform project, where MyLogger should be static to make it available in the whole project.
So I was trying something like:
CODE:.........
The compiler complains about the static. How do I do this? Is it possible at all? If not, what's the right approach?
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Apr 27, 2010
I have an existing C++ library that I want to compile into a static library, and call commands from it with Java on the Android platform. I am brand new to Android development, and just need to figure out how to set the Java interface up so my C++ lib works on the Android. Where do I start?
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Jan 1, 2014
I'm a little new too java programming. Im looking for a means to store groups of static data..so I understand these simple string arrays...
[HIGH]
private static String[] names = new String[] {
"aidanmack",
"johnsmith"
[code]....
But can I not combine that into an array of objects? somthing along the lines of what you would do with json? like...
[HIGH]
private static array[] multi = new array(){
{"name":"AIDANMACK","age":"30"},
{"name":"johnsmith","age":"31"}
}
[/HIGH]
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Sep 3, 2010
I am thinking to create a static method to return a reference to the application instance. I am not sure if it is safe to assume there is only one instance of the Application in one application. Apparently, the Application class in Android SDK doesn't provide such method to return the instance reference. So I suspect there must be a reason?
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Aug 28, 2010
the title say it all. I wanna know a corresponding method in Android/Java that is like the GetTickCount method in C#/C++?
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