导航抽屉活动：单击按钮可从片段移动到片段

问题描述

通过单击按钮从片段移动到另一个片段，是由于覆盖了以下内容

。当我单击按钮时，将同时显示家庭片段和幻灯片片段。

我曾经使用HomeFragment.java中的按钮将代码从家庭片段切换为幻灯片片段

    public View onCreateView(@NonNull LayoutInflater inflater,ViewGroup container,Bundle savedInstanceState) {
        homeviewmodel =
                viewmodelProviders.of(this).get(Homeviewmodel.class);
        View root = inflater.inflate(R.layout.fragment_home,container,false);
        final TextView textView = root.findViewById(R.id.text_home);
        homeviewmodel.getText().observe(getViewLifecycleOwner(),new Observer<String>() {
            @Override
            public void onChanged(@Nullable String s) {
                textView.setText(s);
            }
        });

    Button button = root.findViewById(R.id.button);
    button.setonClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            requireActivity().getSupportFragmentManager()
                    .beginTransaction()
                    .replace(R.id.nav_host_fragment,new SlideshowFragment())
                    .commit();
        }
    });
    return root;
    }

fragment_home.xml中的Button的XML

<Button
    android:id="@+id/button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Button"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.854"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintVertical_bias="0.241" />

container在content_main.xml

中

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:showIn="@layout/app_bar_main">

    <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_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:navGraph="@navigation/mobile_navigation" />
</androidx.constraintlayout.widget.ConstraintLayout>

重现此问题的步骤：

1. 使用导航抽屉活动创建新项目
2. 在fragment_home.xml中添加按钮
3. 在HomeFragment.java中为按钮创建侦听器

在单击按钮时仅显示幻灯片片段我缺少什么？

MainActivity.java以获得奖品

public class MainActivity extends AppCompatActivity {

    private AppBarConfiguration mAppBarConfiguration;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        FloatingActionButton fab = findViewById(R.id.fab);
        fab.setonClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view,"Replace with your own action",Snackbar.LENGTH_LONG)
                        .setAction("Action",null).show();
            }
        });
        DrawerLayout drawer = findViewById(R.id.drawer_layout);
        NavigationView navigationView = findViewById(R.id.nav_view);
        // Passing each menu ID as a set of Ids because each
        // menu should be considered as top level destinations.
        mAppBarConfiguration = new AppBarConfiguration.Builder(
                R.id.nav_home,R.id.nav_gallery,R.id.nav_slideshow)
                .setDrawerLayout(drawer)
                .build();
        NavController navController = Navigation.findNavController(this,R.id.nav_host_fragment);
        NavigationUI.setupActionBarWithNavController(this,navController,mAppBarConfiguration);
        NavigationUI.setupWithNavController(navigationView,navController);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main,menu);
        return true;
    }

    @Override
    public boolean onSupportNavigateUp() {
        NavController navController = Navigation.findNavController(this,R.id.nav_host_fragment);
        return NavigationUI.navigateUp(navController,mAppBarConfiguration)
                || super.onSupportNavigateUp();
    }

}

解决方法

好了，请用slide_show_container（FrameLayout）替换nav_host_fragment。名称可以相同，就是用Framelayout替换片段。

在创建时在首页活动中添加此代码

               getSupportFragmentManager()
                .beginTransaction()
                .replace(R.id.nav_host_fragment,new HomeFragment())
                .commit();

并删除之前建议的代码。

<FrameLayout
    android:id="@+id/nav_host_fragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent" />