问题
I am completely new to Android and I have to submit this app to end my college degree, but I am having this problem where my fragment crashes my entire app.
To explain what I have done up until now is, I have a LoginActivity where I sent the userId through the Intent and have the id of the current user on my DashboardActivity (and I can display it), but in the DashboardActivity I have a bottom navigation bar that navigates to my FormFragment and my DataFragment.
Right now, want I would love to pass the userId value of the current user from the DashboardActivity to my DataFragment, so that I can display dynamically the user data according to the userId.
So with it, I found that the best option is to use bundle, but I don't now why (because I am completely new to this) my app crashes every time I switch from my FormFragment to my DataFragment.
Can you help me? I am desperate xD
This is my DashboardActivity code:
public class PainelActivity extends AppCompatActivity {
private Button buttonLogout;
private TextView textViewId;
private Object DashboardFragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_painel);
BottomNavigationView navView = findViewById(R.id.nav_view);
// Passing each menu ID as a set of Ids because each
// menu should be considered as top level destinations.
AppBarConfiguration appBarConfiguration = new AppBarConfiguration.Builder(
R.id.navigation_home, R.id.navigation_dashboard)
.build();
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
NavigationUI.setupActionBarWithNavController(this, navController, appBarConfiguration);
NavigationUI.setupWithNavController(navView, navController);
// gets the id from the Intent
Intent get = getIntent();
String userId = get.getStringExtra(LoginActivity.EXTRA_ID);
// Send the id to the Fragments
Bundle bundle = new Bundle();
bundle.putString("userId", userId);
Fragment fragment = new Fragment();
fragment.setArguments(bundle);
getSupportFragmentManager().beginTransaction()
.add(R.id.nav_host_fragment, fragment).commit();
// see the id on the screen
textViewId = findViewById(R.id.textViewId);
textViewId.setText(userId);
// logout
buttonLogout = findViewById(R.id.logoutButton);
buttonLogout.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
openMainActivity();
}
});
}
public void openMainActivity() {
Intent HomePage = new Intent(this, MainActivity.class);
startActivity(HomePage);
Toast.makeText(PainelActivity.this, "Terminou a sua sessão.",
Toast.LENGTH_LONG).show();
}
}
And this is my DataFragment code:
public class DashboardFragment extends Fragment {
INodeJS myAPI;
private TextView textViewResult;
public View onCreateView(@NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
View root = inflater.inflate(R.layout.fragment_dashboard, container, false);
//Init API
Retrofit retrofit = RetrofitClient.getInstance();
myAPI = retrofit.create(INodeJS.class);
textViewResult = root.findViewById(R.id.text_view_result);
// gets the id from the activity
if (getArguments() != null) {
String userId = getArguments().getString("userId");
int uid = Integer.parseInt(userId);
Call<List<DataResult>> call = myAPI.executeGetData(uid);
call.enqueue(new Callback<List<DataResult>>() {
@Override
public void onResponse(Call<List<DataResult>> call, Response<List<DataResult>> response) {
if (response.code() == 200) {
List<DataResult> DATA = response.body();
for (DataResult data: DATA) {
String content = "";
content += "Data: " +data.getDta() + "\n";
content += "Hora: " +data.getHora() + "\n";
content += "Glicémia: " +data.getIndiceGlicemia() + "\n";
content += "Insulina: " +data.getInsulina() + "\n";
content += "Medicação: " +data.getMedicacao() + "\n\n";
textViewResult.append(content);
}
}
}
@Override
public void onFailure(Call<List<DataResult>> call, Throwable t) {
textViewResult.setText(t.getMessage());
}
});
}
return root;
}
}
Thank you and have a nice day!
(I just edited my code and updated my question, right now, my app doesn't crash but I don't see the data.)
回答1:
While creating bundle:
Bundle bundle = new Bundle();
bundle.putString("userId", userId);
Fragment fragment = new Fragment();
fragment.setArguments(bundle);
getSupportFragmentManager().beginTransaction()
.replace(R.id.fragment_placeholder_id, dataFragment, "anyTagName").commit();
The To get the data in your fragment:
if (getArguments != null) {
String userId = getArguments().getString("userId");
}
回答2:
When you create a new fragment you have an auto-generated function called newInstance.
So what you need to do is:
public static MyFragment newInstance(String param1, String param2) {
MyFragment fragment = new MyFragment();
Bundle args = new Bundle();
args.putString("ARG_NAME", param1);
args.putString("OTHER_ARG_NAME", param2);
fragment.setArguments(args);
return fragment;
}
Then, in your activity:
String str1 = "foo";
String str2 = "bar";
MyFragment myFragment = MyFragment.newInstance(str1, str2);
FragmentTransaction transaction = getSupportFragmentManager()
.beginTransaction()
.replace(R.id.nameOfActivityLayout, myFragment);
transaction.addToBackStack(null); // Add this line if you want to add the fragment to the back-stack
transaction.commit();
And back to your fragment, in your onCreate method :
String str1;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
str1 = getArguments().getString("ARG_NAME");
}
}
The variable str1 will now have the value "foo" and you're free to use it in your fragment. Of course you can put other types in the bundle, like integers, booleans, arrays etc.
回答3:
You are using the jetpack navigation component, so its easier than before. You just have to pass the bundle to the navigation controller
Do:
navController.setGraph(R.navigation.graph, YOUR_BUNDLE);
then in your start fragment: Bundle b = getArguement(); String id = b.Get string("I'd");
来源：https://stackoverflow.com/questions/62229797/how-to-pass-data-from-activity-to-fragment-using-bundle