#FragmentArgs Annotation Processor to create arguments for android fragments without using reflections.
I have written a blog entry about this library: http://hannesdorfmann.com/android/fragmentargs/
#Dependency Check GradlePlease to get the latest version number.
To generate the Builder classes android annotation processor will be used. In gradle / android studio you need to apply Hugo Visser's awesome android-apt gradle plugin to run annotation processing.
dependencies {
compile 'com.hannesdorfmann.fragmentargs:annotation:1.0.1'
apt 'com.hannesdorfmann.fragmentargs:processor:1.0.1'
}
#How to use
FragmentArgs generates java code at compile time. It generates a Builder class out of your Fragment class.
There are three important things to note:
- Fields MUST have at least package (default) visibility. That means no private, protected or static fields can be annotated with
@Arg. The generated Builder class is in the same package as the Fragment is. Therefore it needs at least package visibility to access the annotated fields. - In the Fragments
onCreate(Bundle)method you have to callFragmentArgs.inject(this)to read the arguments and set the values. - Unlike Eclipse Android Studio does not auto compile your project while saving files. So you may have to build your project to start the annotation processor which will generate the
Builderclasses for your annotated fragments.
Example:
import com.hannesdorfmann.fragmentargs.FragmentArgs;
import com.hannesdorfmann.fragmentargs.annotation.Arg;
public class MyFragment extends Fragment {
@Arg
int id;
@Arg
String title;
@Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
FragmentArgs.inject(this); // read @Arg fields
}
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
Toast.makeText(getActivity(), "Hello " + title,
Toast.LENGTH_SHORT).show();
}
}In your Activity you will use the generated Builder class (the name of your fragment with "Builder" suffix) instead of new MyFragment() or a static MyFragment.newInstance(int id, String title) method.
For example:
public class MyActivity extends Activity {
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
int id = 123;
String title = "test";
// Using the generated Builder
Fragment fragment =
new MyFragmentBuilder(id, title)
.build();
// Fragment Transaction
getFragmentManager()
.beginTransaction()
.replace(R.id.container, fragment)
.commit();
}
}##Optional Arguments
You can specify a fragment argument to be optional by using @Arg(required = false)
For example:
public class MyOptionalFragment extends Fragment {
@Arg
int id;
@Arg
String title;
@Arg(required = false)
String additionalText;
@Arg(required = false)
float factor;
@Arg(required = false)
int mFeatureId;
@Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
FragmentArgs.inject(this); // read @Arg fields
}
}Optional Arguments will genearete a Builder class with additional methods to set optional arguments.
For Example:
public class MyActivity extends Activity {
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
int id = 123;
String title = "test";
// Using the generated Builder
Fragment fragment =
new MyFragmentBuilder(id, title) // required args
.additionalText("foo") // Optional arg
.factor(1.2f) // Optional arg
.featureId(42) // Optional arg
.build();
// Fragment Transaction
getFragmentManager()
.beginTransaction()
.replace(R.id.container, fragment)
.commit();
}
}As you have seen optional fragment arguments are part of the Builder class as an own methods. Since they are optional you can decide if you want to set optinal values or not by calling the corresponding method or skip the corresponding method call.
Like you have seen from the example above fields named with "m" prefix will be automatically cut by making the method name the substring of the original fields name without the "m" prefix. For example the field int mFeatureId corresponds to the builders method featureId(int)
Wouldn't it be painful to overide onCreate(Bundle) in every Fragment of your app just to insert FragmentArgs.inject(this).
FragmentArgs are designed to support inheritance. Hence you can override once onCreate(Bundle) in your Fragment base class and do not need to override this for every single Fragment.
For example:
public class BaseFragment extends Fragment {
@Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
FragmentArgs.inject(this); // read @Arg fields
}
}public class MyFragment extends BaseFragment {
@Arg
String title;
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
Toast.makeText(getActivity(), "Hello " + title,
Toast.LENGTH_SHORT).show();
}
}public class OtherFragment extends BaseFragment {
@Arg
String foo;
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
Toast.makeText(getActivity(), "Hello " + foo,
Toast.LENGTH_SHORT).show();
}
}#Support Fragment
Fragments of the support library are supported. Therefore fields in android.support.v4.app.Fragment or android.app.Fragment can be annotated with @Arg.
#Thanks Many parts of the annotation code are based on Hugo Visser's Bundle project. I have added some optimizations.
React
Typescript
Django
Laravel
Facebook
Microsoft
Google
Alibaba
D3
Tencent