I am trying to get an adapter class to get the intent that was stored in another adapter class. The idea is that the first adapter class will store an intent and start the activity of the second adapter class (Player_Adapter) as shown below:
public static class NBAViewHolder extends RecyclerView.ViewHolder {
public LinearLayout containerView;
public TextView textView;
NBAViewHolder(View view) {
super(view);
containerView = view.findViewById(R.id.nba_row);
textView = view.findViewById(R.id.nba_row_text_view);
containerView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) { //on clicking the TEAMS will transfer the url to the "TEAMSActivity" class
TEAMS current = (TEAMS) containerView.getTag();
//an intent is a "glue" between activities, connecting them. He`re the intent is transferring the
//url that contains the properties of the TEAMS to the class "TEAMSActivity".
//can possibly create a new adapter class
Intent intent = new Intent(v.getContext(), com.example.player.Player_Adapter.class);
//we get the "fullName"
intent.putExtra("id", current.getId());
v.getContext().startActivity(intent);
}
});
}
}
My problem is that I cannot use the getIntent() function from my second adapter class. I have noticed that I was able to use the function in another class that extended "AppCompatActivity". I have also read from another thread that the function is not a part of the Adapter class. Is there any way around this? I am aware that I can just have one adapter class for multiple activity but first I want to resolve this issue, thank you.
Check your Id! Is it empty? And little guidlines:
Create an interface inside of recyclerview.adapter, implement that interface inside of your parent activity(where your adapter placed), then pass your activity instance as created interface inside of adapter and use it inside of onclick listener. The idea is to pass logic of intent to activity.
Interface:
public interface TeamClicker{
void onTeamClicked(int teamId);
}
Create it on top of your adapter.
Create interface variable.
Implement that interface in your activity.
Pass instance of your activity inside of adapter as interface and put it put to your created variable.
Use that interface inside of onclickListener.
Related
I want to create a method that, when implemented in other classes, you just need to pass some parameters and then call the - onclick() function to set the element.
At the moment, I´ve just done this. But this gives me a RunTimeException
Unable to start activity ComponentInfo{com.example.test/com.example.testActivity.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.app.ActivityThread$ApplicationThread android.app.ActivityThread.getApplicationThread()' on a null object reference
my code:
Class: clickeable
imports ...
public class ClickeableOptions implements View.OnClickListener{
private CardView cardView;
private Context cont;
private Class actTarget;
public OpcionesMainClickeables() {}
public ClickeableOptions(CardView cardView, Context cont, Class actTarget) {
this.cardView = cardView;
this.cont = cont;
this.actTarget= actTarget;
}
//Getters and Setters
#Override
public void onClick(View v) {
getCardView().setOnClickListener(this);
Intent intent = new Intent(this.getCont(), this.getActTarget());
startActivity(intent);
}
}
And i want to implement this class like this...
public class MainActivity extends AppCompatActivity{
private CardView cvRegistration;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
cvRegistration = (CardView) findViewById(R.id.cvRegistration);
ClickeableOptions optionRegistration = new ClickeableOptions(
cvRegistration, this, Registration.class
);
optionRegistration.onClick(optionRegistration.getCardView());
}
I've implemented the method in the same file, but I want to do it this way to keep things more tidy.
I think the problem is in the use of this, but i really don't get it
No need to call onClick explicitly from your Activity. Just try like below:
public ClickeableOptions(CardView cardView, Context cont, Class actTarget) {
this.cardView = cardView;
this.cont = cont;
this.actTarget= actTarget;
this.cardView.setOnClickListener(this);
}
And inside onClick
#Override
public void onClick(View v) {
Intent intent = new Intent(getCont(), getActTarget());
getCont().startActivity(intent);
}
And remove this line from Activity.
//optionRegistration.onClick(optionRegistration.getCardView());
Now when you clicked your CardView, Then Activity transitions start.
Try to replace this line:
startActivity(intent);
with
getCont().startActivity(intent);
Also, why are you inheriting ClickeableOptions from AppCompatActivity?
Although you have instantiated the ClickeableOptions (derived from Activity) object, none of its Activity life cycle methods have been called and none of the super class instantiation related work (normally should be done in onCreate) has been accomplished. Hence the ActivityThread is simply null and you've got an exception when invoking
startActivity(intent);
If you want to start another Activity on your CardView click then you need to
follow Leo Leontev's advice:
call
getCont().startActivity(intent)
instead of
startActivity(intent)
move the line
getCardView().setOnClickListener(this)
to the ClickeableOptions custom constructor's most bottom line
delete this line from your MainActivity$onCreate() method:
optionRegistration.onClick(optionRegistration.getCardView());
After all of above is done you'll be able to start new activity on click event.
I am currently recording a message and initialising the objects in one fragment. I'd like to pass it to my main activity. However, I can pass an image between fragments using this:
public void captureImage() {
mCamera.captureImage(new CameraKitEventCallback<CameraKitImage>() {
#Override
public void callback(CameraKitImage cameraKitImage) {
((MainActivity) getActivity()).setBitmapToSend(cameraKitImage.getBitmap());
((MainActivity) getActivity()).openDisplayImageFragment();
}
});
}
I have initialised a media recorder within the class. Is there any way to do this?
If the Main Activity is hosting your fragment, then you can send the data from fragment to its parent Activity by - Interface callbacks or creating a public method in your Activity.
Since you can always get the reference to the parent Activity using getActivity(), you can cast it and pass values to the public method. Eg:
myActivity=(MainActivity) getActivity ();
myActivity.receiveAudio(<"Pass the data as object or in byte[]">);
Sending data from a fragment to another activity require to add Intent extras. Eg:
myIntent.putExtra("myKey",<"Place your object or byte array">);
startActivity(myActivity);
I need to define a layout for multiple activities in android and from the UI part, it is successful. But to code those elements to perform on each click listeners, I need to define it in all the java pages I use.
Can we globally define this in a java page and include it in the required pages?
menuButton = findViewById(R.id.menuButton);
menuButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent i = new Intent(getApplicationContext(), MenuActivity.class);
startActivity(i);
finish();
overridePendingTransition(0, 0);
}
});
Yes and No.
You can create a BaseActivity which has the common logic that has to be executed for each button click.
But you need to implement the listener for the button on specific activity, since life cycle of each activity is independent of other activity.
To make the code readable better (avoiding implementing listener/setOnclickListener), you can use ButterKinfe, and create a method for OnClick() annotation, and call the method in BaseActivity.
What you essentially want to do is call the findViewById(), which can only be called if you have a reference to a Context variable. You should use your Activity Context, hence you pass this to the static function, which can then access all methods accessible via Context .
public class ExampleActivity2 extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
MenuUtils.setListener(this);
}
}
Define the static class like this:
public static class MenuUtils{
public static void setListener(Context context){
menuButton = context.findViewById(R.id.menuButton);
menuButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
// do stuff
}
});
}
}
What you should be careful about is that any Activity you pass to this function should have a menuButton in it's layout, otherwise you run the risk of getting a NullPointerException, which is when findViewById() cannot find menuButton.
I'm trying to define a custom Java class (extending a LinearLayout), which needs to start an activity on click. My code looks like this :
public ArizaSatiri(Context context/*, AttributeSet attrs , final Activity aktivite*/ , JSONObject mysql_satiri)
{
super(context/*, attrs*/);
// code to initialize my view :
final Context finalContext = context;
this.setOnClickListener(new OnClickListener() {#Override
public void onClick(View v) {
Intent newIntent = new Intent(finalContext, ArizaDetaylari.class);
finalContext.startActivity(newIntent);
}//onClick
});
}
But when I clicked on the instantiated view, I get the error :
Calling startActivity() from outside of an Activity context requires the
FLAG_ACTIVITY_NEW_TASK flag. Is this really what you want?
As you can see from the code, I tried passing the Activity to the constructor, and that worked. But is that the correct way? Which way would you reccomend ?
Edit:
And I also need to call setTypeFace() at some point. Should I use context, or Activity for that ?
Try this:
this.setOnClickListener(new OnClickListener() {#Override
public void onClick(View v) {
Intent newIntent = new Intent(finalContext, ArizaDetaylari.class);
newIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
finalContext.startActivity(newIntent);
}//onClick
});
You can put your code into onAttachedToWindow() of your custom view class.
#Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();
setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
final Context context = ArizaSatiri.this.getContext();
Intent intent = new Intent(context , ArizaDetaylari.class);
context.startActivity(intent);
}
});
}
This helps because this function is called after your view is added to the activity, the view has the reference of it. Constructor of views probably run before being added to the activity, thus the error.
This should also work if you declare your view in xml instead of creating it programmatically. (Not tested yet)
If take a look to the Context class reference you could see that Activity is an indirect subclass. So if you use an Activity as Context your code should work.
For example:
public ArizaSatiri(Context context, JSONObject mysql_satiri){ ...}
you can change the call to the ArizaSatiri constructor:
new ArizaSatiri(myActivity, mysql_satiri);
Hope it helps.
If context (finalContext) that you are using is referring to ApplicationContext then you need to use the flag. Just add the sentence newIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); before finalContext.startActivity(newIntent);
Problem with this approach especially when you are starting something outside of your app for ex: mail client etc, is it will continue to be there in the recent apps stack even after the activity is completed, in case of mail client it continues to be there even after mail has been sent
I am at baby step level of programming on Android (and in Java in general). I do understand that Activity inherits from the Context class. However in every code snippet I have come across, every time a context must be mentionned, it is set to "this".
My question is : when is a context different from "this" ? Could you provide an real life example of context needing to be different from "this"?
Thank you very much.
Typically, you will want to use this when you are "inside" of an Activity. However, when you are using for example a Helper class, the reference this will not work. An example can be something like this:
public class MyActivity extends Activity
{
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_NOSENSOR);
}
}
A case, where you cannot:
public class MyHelper
{
/* some code of yours */
public void lockOrientation(Activity activity)
{
activity.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_NOSENSOR);
}
}
The above code locks the orientation to the current orientation. Notice that you need to supply the method with an Activity parameter, since you cannot use:
this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_NOSENSOR);
In the first example, you could use this to achieve this, because you were "inside" of an Activity.
Another type of example, how do you set onClickListener.
First example, when you use this:
public class MyActivity extends Activity implements View.OnClickListener
{
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
Button btn=(Button)findViewById(R.id.mybutton);
btn.setOnClickListener(this);
}
#Override
public void onClick(View v)
{
//handle the click event
}
}
In this example, you can use this because in the first line, we wrote implements View.OnClickListener, so the class inherits from the given interface. Without the implements thingie, you couldn't do it. An example of setting the onClickListener without this:
public class MyActivity extends Activity
{
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
Button btn=(Button)findViewById(R.id.mybutton);
btn.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View v)
{
//handle the click event
}
});
}
}
In the second example, we are defining an Anonymous Inner Class, which will handle the click event of the button. Notice that in this case, our Activity does NOT implements View.OnClickListener.
In Outer Class you directly use "this" reference
In Inner Class Or Abstract Class implementation Or Interface implementation use "classname.this" reference
Example:
class Example{
int number = 0;
public Example(int number){
this.number = number;
}
}
notice that number in the contructor and number in the class are not the same. Altough they have the same name. Saying number = number doesn't make sense. Be using this you can asses number in the class.
For example when you are implementing an OnClickListener the "this" is different.
this is a reference to the current object — the object whose method or constructor is being called.
Inside an Activity's method this can be used as a Context object because Activity inherits from ContextThemeWrapper, which inherits from ContextWrapper, which inherits from Context.
A Fragment on the other hand does not inherit from Context. So to get the Context inside a Fragment you would have to call getActivity() for example.
This applies to any object you are calling this from.
Consider you are inside the OnClick() method of a View.OnClickListener and you want to start an Activity:
button.setOnClickListener (new View.OnClickListener() {
public void onClick(View v) {
Intent intent = new Intent(this, NextActivity.class); // wrong because 'this' is the OnClickListener object
Intent intent = new Intent(CurrentActivity.this, NextActivity.class); // correct because 'this' is the CurrentActivity object
startActivity(intent);
}
});