Implement multiple event listeners in the same fragment - Android
You can do:
public class FragmentTypeSelect extends Fragment
implements OnItemSelectedListener, OnClickListener {
RobT
I currently work in a large Multinational designing changes to a large BackEnd System running over Oracle. I've taken up Android programming out of interest and to add another string to my bow.
Updated on December 09, 2020Comments
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RobT over 3 years
I have a fragment which consists of a spinner and a button. You select one of four options with the spinner and then the button will take you to the next activity.
In order to implement the spinner I need to implement onItemSelectedListener on the Fragment but to use the button I need to implement onClickListener. But I can't do both??? I would have expected this to be a really simple thing and the need to have multiple different Event listeners on a View must be common, so how do you implement this?
Here is the code that I am using:-
public class FragmentTypeSelect extends Fragment implements OnItemSelectedListener {
@Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){ // set the view so that it can be referenced View theView = inflater.inflate(R.layout.fragment_type_select, container,false); // set OnClickListener for the button setUpClickListener(theView,R.id.but_select); //=============================== // NEW TYPE SPINNER //=============================== Spinner spinner = (Spinner) theView.findViewById(R.id.new_type_spinner); spinner.setOnItemSelectedListener((OnItemSelectedListener) this); // Create an ArrayAdapter using the string array and a default spinner layout ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(getActivity(), R.array.types_array, android.R.layout.simple_spinner_item); // Specify the layout to use when the list of choices appears adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); // Apply the adapter to the spinner spinner.setAdapter(adapter); return theView; } public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) { TextView headingText = (TextView)getView().findViewById(R.id.new_diet_type_text_heading); TextView detailText = (TextView)getView().findViewById(R.id.new_diet_type_text_detail); if (pos == 0) { headingText.setText(R.string.heading_type_1); detailText.setText(R.string.detail_type_1); } if (pos == 1) { headingText.setText(R.string.heading_type_2); detailText.setText(R.string.detail_type_2); } if (pos == 2) { headingText.setText(R.string.heading_type_3); detailText.setText(R.string.detail_type_3); } if (pos == 3) { headingText.setText(R.string.heading_type_4); detailText.setText(R.string.detail_type_4); } } @Override public void onNothingSelected(AdapterView<?> arg0) { // TODO Auto-generated method stub } public void onClick(View view){ Toast.makeText(getActivity(), "Clicked", Toast.LENGTH_LONG).show(); } private void setUpClickListener(View theView, int childViewID) { View childView = theView.findViewById(childViewID); childView.setOnClickListener((OnClickListener) this); }
}
Originally I just had the spinner in and got this working fine. I then tried to put in the button function with the set OnClickListener in the onCreateView and adding the additional onClick and setUpClickListener methods. This is exactly how I have done it elsewhere but in other cases I have not had other events to handle and have made the class implement the onClickListener. Java does not support multiple interface implements (as I understand it) and hence my question.
Hope you can help. I'm probably being a bit thick but I am still quite new to the whole OO as well as Android.
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Leo Landau almost 11 yearsYou can do both. Post your code, and explain your issue more please.
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RobT almost 11 yearsLeo, I have now posted the code above....Thanks
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RobT almost 11 yearsThat worked fine. I had tried this with a lower case onClickListener rather than OnClickListener and then when I searched for a solution everywhere seemed to say that you couldn't implement multiple interfaces separated by commas. Thanks for the clarification.
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Xsmael over 9 yearsI've also seen a lot, that in java it is not possible to implement several interfaces, but anyway is that a good practice ? do you recommand this way ?
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Leo Landau over 9 years@Xsmael In Java you are allowed to implement multiple interfaces. And yes, I would say that this is a perfectly acceptable practice. Here you could use anonymous inner classes for the listeners too, but that's just a matter of code style, either style is fine in practice.