I have a public void in one class and I want to call it in another class when it creates but nothing seems to be working. here is the code of my first activity
public class activityone extends Activity {
public void actionC() {
//actions
}
Does anyone know how to call it in my second class?
In general, you need to have an instance of your activityone class in order to call an instance method.
To create an instance, you generally use a constructor like:
activityone a = new activityone();
a.actionC();
I'm not sure this is what you want though, because Activitys are generally created by the Android system itself and you should handle the onCreate method instead.
Here is what you can do:
public class activityone extends Activity {
/*public void actionC() {*/ //Instead on normal method, write your actions in onCreate()
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//actions
}
and in your second activity, do this:
Intent intent = new Intent(getApplicationContext(),activityone.class);
startActivity(intent);
Hope it helps !!!
Related
Please please don't minus my question i confused when googling.
I used Android Tab Layout with Swipeable Views in my code for when user pressed setting button on an activity.
now I need send message from TopRatedFragment.java that extends from fragment to the activity that call the mainActivity of "Android Tab Layout with Swipeable Views".
You can do this by implementing a call back
create an interface first
public interface CommunicationInterface {
public void onSuccess();
public void onFailed();
}
then in your activity implement the interface
public class YourActivity extends ActionBarActivity implements CommunicationInterface {
//default functions
#Override
public void onSuccess() {
//stuff you want to do in the acivity
}
#Override
public void onFailed() {
//stuff you want to do in the acivity
}
}
Now in the fragment
public class yourfragment extends Fragment {
CommunicationInterface callback;
//stuffs that usually come in yor fragment and like OncreateView etc
#Override
public void onActivityCreated(#Nullable Bundle outState) {
super.onActivityCreated(outState);
//after all the stuff you want to do in your fragment then implement //call back function to communicate with the activity
callback= (CommunicationInterface) getActivity();
callback.onSuccess();//according to your purpose use where ever you like
callback.onFailed();//according to your purpose use where ever you like
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
callback= (CommunicationInterface) activity;
}
}
Take a close look on this reference:
Creating event callbacks to the activity
The android docs recommend using this pattern of having the parent activity implement an interface of the fragment (Basically calling methods on it)
class MyFragment extends Fragment {
interface Listener {
public void onSomeEvent();
}
private void somethingHappeninInTheFragment() {
// let the activity know
((Listener) getActivity()).onSomeEVent();
}
}
class MyActivity extends Activity implements MyFragment.Listener {
// etc
#Override
public void onSomeEvent() {
// handle the message from the fragment
}
}
Explained with a more concrete example here: http://developer.android.com/guide/components/fragments.html#EventCallbacks
Here's the solution:
Step 1 : From your fragment.
Intent i = new Intent(getActivity(), YourActivity.class);
i.putExtra("key", "Your value1");
i.putExtra("key2", "Your value2");
i.putExtra("key3", "Your value3");
getActivity().startActivity(i);
Step 2 : In your Activity where you want the result
Intent getResults = getIntent();
String firstValue = getResults.getStringExtra("key1");
String secondValue = getResults.getStringExtra("key2");
String thirdValue = getResults.getStringExtra("key3");
Use those values your needs are.
Hope this helps.. :)
In Android (targeting APIs 14-16) I have a MainActivity and a NextActivity. There is no difficulty using intents to start NextActivity from within MainActivity if the getIntent() method is called inside the onCreate() block of NextActivity:
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
int data = 7;
...
Intent intent = new Intent(this, NextActivity.class);
intent.putExtra("data", data);
startActivity(intent);
}
}
public class NextActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
final int data = this.getIntent().getIntExtra("data", 7);
...
}
...
}
However, since the field data is being used inside an anonymous ("inner") class in NextActivity, I am compelled to declare it final.
I'd prefer not to declare fields final, and I can usually avoid doing so if I declare them at the beginning of the class, before onCreate() begins. But for some reason, the app crashes when NextActivity starts if the getIntent() statement appears (without the final keyword) outside of onCreate().
Any idea why?
You can't getIntent() before onCreate() -- there's simply no Intent available at that point. I believe the same is true for anything that requires a Context.
Your anonymous inner class can still call getIntent(), however, so you don't need to declare this as a variable at all.
According to your question what i understand is u don't want to declare data as final in next activity..Then y cant u try for this./
public class NextActivity extends Activity {
int data=0;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
data = this.getIntent().getIntExtra("data", 7);
...
}
...
}
Try this...
I have created a function
public void setTabHome(int index) { }
on main.java page. This function is to set the page by index.
By default, index is 0. I want to call main.java page from main1.java with the parameter index set to 1.
You can set the method to static and then call it again.
I would just insert that method again in main1.java though ¯_(ツ)_/¯
or even better access main1.java through an Intent.
public static void setTabHome(int index) { }
main.setTabHome(indexnumber)
Make an instance of your main.java class in main1.java class. Using this instance, you can call the function in main.java. Like this
Main main = new Main();
main.yourfunctionName();
But better you make another function in main1.java and use this function. Beacuse the parameters you used in one activity may cannot be used in another activity.
main.java define a public static instance in the class
public class Menu extends Activity{
public static Menu instance = null;
#Override
public void onCreate(Bundle savedInstanceState) {
instance = this;
}
public void setTabHome(int index) { }
}
main1.java call like this:
Menu.instance.setTabHome(number);
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Android: How to declare global variables?
I want to access public instance variable in main activity from other activity.
And I want to call public method in main activity.
How can I do that?
class MainActivity extends Activity {
public int i;
public void myMethod() {}
}
class MyActivity extends Activity {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// How can I access variable i in MainActivity?
// And How can I call myMethod() in MainActivity?
}
}
This is not recommended, as your activity class may be recycled by the system at any time.
Use preferences to store variables, or simplier : create your own Application class. This one will be available during all the application life, and you'll be able to store static variable in it.
You can pass it as an extra in the Intent with wich you start your new Activity.
This might help you:
How to declare global variables in Android?
You can use a subclass of Application, SharedPreferences or static variables.
Try this
class MainActivity extends Activity {
public int i;
void startNewA()
{
Intent i = new Intent(getApplicationContext(), MyActivity.class);
i.putExtra("var_name", i);
startNewActivity(i);
}
}
class MyActivity extends Activity {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
int i = getIntent().getIntExtra("var_name", -1);
}
}
When you want to get and set the same variabl in more than one activity you could also use the prferences.
I am currently working on an android project and I have an activity, lets call it MyActivity and this activity calls a standard Java class called MyClass.
I need MyClass to finish the MyActivity activity but I can't find out how to do this. I thought I might be able to pass the context to the standard java class and call context.finish() but this doesn't appear to be available.
How can I do this, thanks for any help you can offer.
You can pass the Context, but you will need to cast it to an Activity (or simply pass the Activity itself), although this in general seems like a bad practice.
The most secure solution uses listener and a Handler. It is complex, but ensures a non direct call to finish activity.
Your listener:
interface OnWantToCloseListener{
public void onWantToClose();
}
Class that should close activity.
class MyClass {
private OnWantToCloseListener listener;
public void setWantToCloseListener(OnWantToCloseListener listener){
this.listener = listener;
}
private void fireOnWantToClose(){
if(this.listener != null)
listener.onWantToClose();
}
}
When you want to close your activity you must call fireOnWantToClose() method.
public MyActivity extends Activity{
public void onCreate(){
final int CLOSE = 1; //number to identify what happens
MyClass my_class = new MyClass();
final Handler handler = new Handler(){
public void handleMessage(Message msg){
if(msg.what == CLOSE)
MyActivity.this.finish();
}
});
my_class.setOnWantToCloseListener(new OnWantToCloseListener(){
public void onWantToClose(){
handler.sendEmptyMessage(CLOSE);
}
});
}
}
This is secure because Activity is not finished directly by MyClass object, it is finished through a listener that orders a handler to finish activity. Even if you run MyClass object on a second thread this code will works nice.
EDIT: CLOSE var added I forget to declare and initialize this.
Pass the MyActivity to MyClass as an Activity. From there you can call myActivity.finish();
For example:
private Activity myActivity;
public MyClass(Activity myActivity){
this.myActivity = myActivity;
}
public void stopMyActivity(){
myActivity.finish();
}
And in MyActivity:
MyClass myClass = new MyClass(this);
This is risky, because you're holding a reference to an Activity, which can cause memory leaks.
If your java class is a nested inner class, you can use:
public class MyActivity extends Activity {
public static class JavaClass {
public void finishActivity() {
MyActivity.finish();
}
}
}
Otherwise you'll have to pass the java class a Context (i.e. pass it a reference to this, since Activity extends Context) and store it as a private instance variable.