此NavController不知道操作

Question

我以两种不同的方式提供片段之间的数据传输，首先是正常工作，而安全的数据类型会导致运行时崩溃。我正在使用该Android文档：https : //developer.android.com/topic/libraries/architecture/navigation/navigation-implementing#Safe-args

不明白如何解决该问题。谢谢你的帮助

07-13 11:40:07.986 8119-8119/com.flexdecision.ak_lex.navigationsimple E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.flexdecision.ak_lex.navigationsimple, PID: 8119
java.lang.IllegalArgumentException: navigation destination com.flexdecision.ak_lex.navigationsimple:id/transferAction is unknown to this NavController
    at androidx.navigation.NavController.navigate(NavController.java:669)
    at androidx.navigation.NavController.navigate(NavController.java:628)
    at androidx.navigation.NavController.navigate(NavController.java:690)
    at com.flexdecision.ak_lex.navigationsimple.InitialFragment.makeTransfer(InitialFragment.java:58)
    at com.flexdecision.ak_lex.navigationsimple.InitialFragment.lambda$onViewCreated$0(InitialFragment.java:47)
    at com.flexdecision.ak_lex.navigationsimple.-$$Lambda$InitialFragment$shEoLbIe0sVhbTcJ2Al_FvBuU7g.onClick(lambda)
    at android.view.View.performClick(View.java:5198)
    at android.view.View$PerformClick.run(View.java:21147)
    at android.os.Handler.handleCallback(Handler.java:739)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:148)
    at android.app.ActivityThread.main(ActivityThread.java:5417)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

导航图：

07-13 11:40:07.986 8119-8119/com.flexdecision.ak_lex.navigationsimple E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.flexdecision.ak_lex.navigationsimple, PID: 8119
java.lang.IllegalArgumentException: navigation destination com.flexdecision.ak_lex.navigationsimple:id/transferAction is unknown to this NavController
    at androidx.navigation.NavController.navigate(NavController.java:669)
    at androidx.navigation.NavController.navigate(NavController.java:628)
    at androidx.navigation.NavController.navigate(NavController.java:690)
    at com.flexdecision.ak_lex.navigationsimple.InitialFragment.makeTransfer(InitialFragment.java:58)
    at com.flexdecision.ak_lex.navigationsimple.InitialFragment.lambda$onViewCreated$0(InitialFragment.java:47)
    at com.flexdecision.ak_lex.navigationsimple.-$$Lambda$InitialFragment$shEoLbIe0sVhbTcJ2Al_FvBuU7g.onClick(lambda)
    at android.view.View.performClick(View.java:5198)
    at android.view.View$PerformClick.run(View.java:21147)
    at android.os.Handler.handleCallback(Handler.java:739)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:148)
    at android.app.ActivityThread.main(ActivityThread.java:5417)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

活动布局：

<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/nav_graph"
    app:startDestination="@id/initialFragment">

    <fragment
        android:id="@+id/initialFragment"
        android:name="com.flexdecision.ak_lex.navigationsimple.InitialFragment"
        android:label="fragment_initial"
        tools:layout="@layout/fragment_initial">
        <action
            android:id="@+id/transferAction"
            app:destination="@+id/nextFragment" />
    </fragment>
    <fragment
        android:id="@+id/nextFragment"
        android:name="com.flexdecision.ak_lex.navigationsimple.NextFragment"
        android:label="fragment_next"
        tools:layout="@layout/fragment_next" >
        <argument
            android:name="firstName"
            android:defaultValue="none"
            app:type="string" />
        <argument
            android:name="lastName"
            android:defaultValue="none"
            app:type="string" />
    </fragment>
</navigation>

发件人：

<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <fragment
        android:id="@+id/nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:defaultNavHost="true"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:navGraph="@navigation/nav_graph" />
</android.support.constraint.ConstraintLayout>

接收方：

import androidx.navigation.Navigation;

public class InitialFragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_initial, container, false);
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        Button transactionBtn = view.findViewById(R.id.transaction);
        transactionBtn.setOnClickListener(v -> makeTransfer(v));
    }

    private void makeTransfer(View view) {
        Bundle bundle = new Bundle();
        bundle.putString("name", "Aleksey");
        Navigation.findNavController(view).navigate(R.id.transferAction, bundle);

        //Type safe passing data
        InitialFragmentDirections.TransferAction action = InitialFragmentDirections.transferAction();
        action.setLastName("Petrov");
        Navigation.findNavController(view).navigate(action);
    }
}

额外：

public class NextFragment extends Fragment {
    private static final String ARG_PARAM1 = "name";

    private String mParam1;
    private TextView firstName;

    public NextFragment() {
        // Required empty public constructor
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);
            Log.d("Next", "Param: " + mParam1);
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_next, container, false);
    }


    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        firstName = view.findViewById(R.id.firstName);
        TextView lastName = view.findViewById(R.id.lastNameTV);
        firstName.setText(mParam1);

        String ln = NextFragmentArgs.fromBundle(getArguments()).getLastName();
        lastName.setText(ln);
    }
}

Answer 1

您两次调用“ Navigation.findNavController（view）.navigate”：

private void makeTransfer(View view) {
    Bundle bundle = new Bundle();
    bundle.putString("name", "Aleksey");
    Navigation.findNavController(view).navigate(R.id.transferAction, bundle);

    //Type safe passing data 
    InitialFragmentDirections.TransferAction action = InitialFragmentDirections.transferAction();
    action.setLastName("Petrov");
    Navigation.findNavController(view).navigate(action);
} 

第一次使用bundle和第二次使用安全的args，但是在第一次调用之后，您的目的地已更改为“ nextFragment”，并且当您调用第二个“ navigate”时，“ NavController”在“ nextFragment”中查找“ transferAction”操作并引发异常。

Answer 2

就我而言，我试图从片段 A 导航到片段 B，但片段 A 没有通过导航控制器导航到（也称为导航图中不存在），它是我显式初始化的片段，从 FragmentStateAdater 初始化（绑定到 ViewPager）。解决方案是创建一个针对片段 B 的全局操作，而不是从片段 A 到片段 B 的全局操作