我刚开始在 Android 中使用 Jetpack Navigation 组件和 SafeArgs 进行导航。但是，我不明白如何从一个目的地导航到另一个目的地（我阅读了谷歌文档，但这让我感到困惑）。所以我有一个 Menu_Fragment 类，它在 NavGraph 中有一个指向 Softdrink 类的链接。自动创建了一个 Menu_FragmentDirections 类。但是，我不知道如何在 Menu_Fragment 类中使用它来实现 OnClick 侦听器事件。在这里，我在 Menu_Fragment 类中有 onClick 方法（请参阅https://developer.android.com/guide/navigation/navigation-navigate）：
@Override
public void onClick(View view) {
if(view.getId() == R.id.imageButton_Softdrinks_en) {
float amount = ...;
action =
Menu_FragmentDirections
.actionMenuFragmentToSoftdrinks(amount);
Navigation.findNavController(view).navigate(action);
}
}
在这里您可以看到 Menu_FragmentDirections 类：
package com.example.td.barapp;
import androidx.annotation.NonNull;
import androidx.navigation.ActionOnlyNavDirections;
import androidx.navigation.NavDirections;
public class Menu_FragmentDirections {
private Menu_FragmentDirections() {
}
@NonNull
public static NavDirections actionMenuFragmentToSoftdrinks() {
return new ActionOnlyNavDirections(R.id.action_menu_Fragment_to_softdrinks);
}
}
在这里你可以看到 NavGraph：
<?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/menu_Fragment">
<fragment
android:id="@+id/menu_Fragment"
android:name="com.example.td.barapp.Menu_Fragment"
android:label="fragment_menu_"
tools:layout="@layout/fragment_menu" >
<action
android:id="@+id/action_menu_Fragment_to_softdrinks"
app:destination="@id/softdrinks" />
</fragment>
<fragment
android:id="@+id/softdrinks"
android:name="com.example.td.barapp.Softdrinks"
android:label="fragment_softdrinks"
tools:layout="@layout/fragment_softdrinks" />
</navigation>
谁能告诉我，我必须在上面发布的 onCreateMethod() 中做什么。我收到错误消息：“无法解析符号‘操作’”和“无法解析符号‘导航’”（当然还有使用错误意外的标记 '...'）
我会很感激每一条评论，并非常感谢您的帮助。
这里更新的是带有 onCreateMethod 的完整 Menu_Fragment 类：
package com.example.td.barapp;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import com.example.td.barapp.databinding.FragmentMenuBinding;
/**
* A simple {@link Fragment} subclass.
* Use the {@link Menu_Fragment#newInstance} factory method to
* create an instance of this fragment.
*/
public class Menu_Fragment extends Fragment implements View.OnClickListener {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private Menu_Fragment() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment Menu_Fragment.
*/
// TODO: Rename and change types and number of parameters
public static Menu_Fragment newInstance(String param1, String param2) {
Menu_Fragment fragment = new Menu_Fragment();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
private FragmentMenuBinding binding;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
binding = FragmentMenuBinding.inflate(inflater, container, false);
return binding.getRoot();
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
binding.imageButtonCocktailsEn.setOnClickListener(this);
binding.imageButtonCocktailsAlcfreeEn.setOnClickListener(this);
binding.imageButtonLongdrinksEn.setOnClickListener(this);
binding.imageButtonWhiskyEn.setOnClickListener(this);
binding.imageButtonLiquorEn.setOnClickListener(this);
binding.imageButtonBeerEn.setOnClickListener(this);
binding.imageButtonSoftdrinksEn.setOnClickListener(this);
binding.imageButtonHotDrinksEn.setOnClickListener(this);
}
public void onDestroyView() {
super.onDestroyView();
binding = null;
}
@Override
public void onClick(View view) {
if(view.getId() == R.id.imageButton_Softdrinks_en) {
float amount = 0f;
Menu_FragmentDirections.ActionMenuFragmentToSoftdrinks action = Menu_FragmentDirections
.actionMenuFragmentToSoftdrinks(amount);
}
}
}
