How to handle button clicks using the XML onClick within Fragments
Solution 1:
I prefer using the following solution for handling onClick events. This works for Activity and Fragments as well.
public class StartFragment extends Fragment implements OnClickListener{
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_start, container, false);
Button b = (Button) v.findViewById(R.id.StartButton);
b.setOnClickListener(this);
return v;
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.StartButton:
...
break;
}
}
}
Solution 2:
You could just do this:
Activity:
Fragment someFragment;
//...onCreate etc instantiating your fragments
public void myClickMethod(View v) {
someFragment.myClickMethod(v);
}
Fragment:
public void myClickMethod(View v) {
switch(v.getId()) {
// Just like you were doing
}
}
In response to @Ameen who wanted less coupling so Fragments are reuseable
Interface:
public interface XmlClickable {
void myClickMethod(View v);
}
Activity:
XmlClickable someFragment;
//...onCreate, etc. instantiating your fragments casting to your interface.
public void myClickMethod(View v) {
someFragment.myClickMethod(v);
}
Fragment:
public class SomeFragment implements XmlClickable {
//...onCreateView, etc.
@Override
public void myClickMethod(View v) {
switch(v.getId()){
// Just like you were doing
}
}
Solution 3:
The problem I think is that the view is still the activity, not the fragment. The fragments doesn't have any independent view of its own and is attached to the parent activities view. Thats why the event ends up in the Activity, not the fragment. Its unfortunate, but I think you will need some code to make this work.
What I've been doing during conversions is simply adding a click listener that calls the old event handler.
for instance:
final Button loginButton = (Button) view.findViewById(R.id.loginButton);
loginButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(final View v) {
onLoginClicked(v);
}
});
Solution 4:
I've recently solved this issue without having to add a method to the context Activity or having to implement OnClickListener. I'm not sure if it is a "valid" solution neither, but it works.
Based on: https://developer.android.com/tools/data-binding/guide.html#binding_events
It can be done with data bindings: Just add your fragment instance as a variable, then you can link any method with onClick.
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
tools:context="com.example.testapp.fragments.CustomFragment">
<data>
<variable android:name="fragment" android:type="com.example.testapp.fragments.CustomFragment"/>
</data>
<LinearLayout
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/ic_place_black_24dp"
android:onClick="@{() -> fragment.buttonClicked()}"/>
</LinearLayout>
</layout>
And the fragment linking code would be...
public class CustomFragment extends Fragment {
...
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_person_profile, container, false);
FragmentCustomBinding binding = DataBindingUtil.bind(view);
binding.setFragment(this);
return view;
}
...
}
Solution 5:
ButterKnife is probably the best solution for the clutter problem. It uses annotation processors to generate the so called "old method" boilerplate code.
But the onClick method can still be used, with a custom inflator.
How to use
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup cnt, Bundle state) {
inflater = FragmentInflatorFactory.inflatorFor(inflater, this);
return inflater.inflate(R.layout.fragment_main, cnt, false);
}
Implementation
public class FragmentInflatorFactory implements LayoutInflater.Factory {
private static final int[] sWantedAttrs = { android.R.attr.onClick };
private static final Method sOnCreateViewMethod;
static {
// We could duplicate its functionallity.. or just ignore its a protected method.
try {
Method method = LayoutInflater.class.getDeclaredMethod(
"onCreateView", String.class, AttributeSet.class);
method.setAccessible(true);
sOnCreateViewMethod = method;
} catch (NoSuchMethodException e) {
// Public API: Should not happen.
throw new RuntimeException(e);
}
}
private final LayoutInflater mInflator;
private final Object mFragment;
public FragmentInflatorFactory(LayoutInflater delegate, Object fragment) {
if (delegate == null || fragment == null) {
throw new NullPointerException();
}
mInflator = delegate;
mFragment = fragment;
}
public static LayoutInflater inflatorFor(LayoutInflater original, Object fragment) {
LayoutInflater inflator = original.cloneInContext(original.getContext());
FragmentInflatorFactory factory = new FragmentInflatorFactory(inflator, fragment);
inflator.setFactory(factory);
return inflator;
}
@Override
public View onCreateView(String name, Context context, AttributeSet attrs) {
if ("fragment".equals(name)) {
// Let the Activity ("private factory") handle it
return null;
}
View view = null;
if (name.indexOf('.') == -1) {
try {
view = (View) sOnCreateViewMethod.invoke(mInflator, name, attrs);
} catch (IllegalAccessException e) {
throw new AssertionError(e);
} catch (InvocationTargetException e) {
if (e.getCause() instanceof ClassNotFoundException) {
return null;
}
throw new RuntimeException(e);
}
} else {
try {
view = mInflator.createView(name, null, attrs);
} catch (ClassNotFoundException e) {
return null;
}
}
TypedArray a = context.obtainStyledAttributes(attrs, sWantedAttrs);
String methodName = a.getString(0);
a.recycle();
if (methodName != null) {
view.setOnClickListener(new FragmentClickListener(mFragment, methodName));
}
return view;
}
private static class FragmentClickListener implements OnClickListener {
private final Object mFragment;
private final String mMethodName;
private Method mMethod;
public FragmentClickListener(Object fragment, String methodName) {
mFragment = fragment;
mMethodName = methodName;
}
@Override
public void onClick(View v) {
if (mMethod == null) {
Class<?> clazz = mFragment.getClass();
try {
mMethod = clazz.getMethod(mMethodName, View.class);
} catch (NoSuchMethodException e) {
throw new IllegalStateException(
"Cannot find public method " + mMethodName + "(View) on "
+ clazz + " for onClick");
}
}
try {
mMethod.invoke(mFragment, v);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new AssertionError(e);
}
}
}
}