带片段的底部导航栏 [英] Bottom Navigation bar with fragments

问题描述

我的主要活动中有一个底部导航栏.通过单击底部导航中的一个选项卡，我想更改视图中的片段.我有以下代码:主要活动:

I have a bottom navigation bar in my Main Activity. By clicking on one of the tabs in my bottom navigation, I want to change the fragment in the view. I have the following code: Main Activity:

public class StartActivity extends AppCompatActivity {

SwiftFragment swiftFragment;
FrameworksFragment frameworksFragment;
FrameLayout content;
android.support.v4.app.FragmentManager fragmentManager;

private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
        = new BottomNavigationView.OnNavigationItemSelectedListener() {

    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
        android.support.v4.app.FragmentTransaction transaction = fragmentManager.beginTransaction();

        switch (item.getItemId()) {
            case R.id.navigation_home:
                Log.i("Nachricht", "HOME");
                return true;
            case R.id.navigation_swift:
                Log.i("Nachricht", "SWIFT");
                transaction.replace(android.R.id.content, swiftFragment);
                transaction.commit();
                return true;
            case R.id.navigation_frameworks:
                Log.i("Nachricht", "FRAMEWORKS");
                transaction.replace(android.R.id.content, frameworksFragment);
                transaction.commit();
                return true;
            case R.id.navigation_profile:
                Log.i("Nachricht", "PROFILE");
        }
        return false;
    }
};

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_start);

    BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
    navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);

    swiftFragment = (SwiftFragment) android.support.v4.app.Fragment.instantiate(this, SwiftFragment.class.getName(), null);
    frameworksFragment = (FrameworksFragment) android.support.v4.app.Fragment.instantiate(this, FrameworksFragment.class.getName(), null);
    content = (FrameLayout) findViewById(android.R.id.content);
    fragmentManager = getSupportFragmentManager();
}

}

我的一个片段:

public class SwiftFragment extends Fragment {

ArrayList<ModelTutorial> items;
ListView list;
ArrayAdapter adapter;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_swift, container, false);

    //TODO: Get Firebase Data
    items = new ArrayList<>();
    items.add(new ModelTutorial("Swift Anlegen der Liste", "TableView", "Test Test Test", null, null));
    items.add(new ModelTutorial("Anlegen der Liste", "TableView", "Test Test Test", null, null));
    items.add(new ModelTutorial("Anlegen der Liste", "TableView", "Test Test Test", null, null));

    list = (ListView) view.findViewById(R.id.swiftTutorialsList);
    adapter = new ListAdapter(getActivity(), items);
    list.setAdapter(adapter);

    return view;
}

}

如果我单击选项卡之一，则会显示右侧的片段，因此可以正常工作.但是，当出现新的片段，而我想单击另一个选项卡以显示另一个片段时，这将不起作用.底部导航栏对点击没有反应.即使 Log.i 语句也不起作用，因此似乎没有调用 OnNavigationItemSelectedListener .

If I click on one of the tabs, the right fragment shows up, so this is working. However when the new fragment shows up and I want to click on another tab to show another fragment, this doesn't work. The bottom navigation bar doesn't react on the clicks. Even the Log.i statements doesn't work, so it seems the OnNavigationItemSelectedListener isn't called.

我对android开发是完全陌生的，我不明白为什么这不起作用.如果有人可以帮助我解决我的问题，我将不胜感激.

I'm completely new to android development and I don't understand why this isn't working. I would appreciate it if someone could help me with my problem.

XML文件StartActivity:

XML File StartActivity:

<?xml version="1.0" encoding="utf-8"?>
<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:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.marcelspindler.codingtutorials.StartActivity">

<android.support.design.widget.BottomNavigationView
    android:id="@+id/navigation"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_marginEnd="0dp"
    android:layout_marginStart="0dp"
    android:background="?android:attr/windowBackground"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:menu="@menu/navigation" />
</android.support.constraint.ConstraintLayout>

XML文件片段:

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.marcelspindler.codingtutorials.SwiftFragment">

<!-- TODO: Update blank fragment layout -->

<ListView
    android:id="@+id/swiftTutorialsList"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />
</FrameLayout>

推荐答案

您需要将Fragment添加到MainActivity内部的容器中.

You need to add the Fragment to a container inside your MainActivity.

尝试这样的事情:

<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:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.marcelspindler.codingtutorials.StartActivity">

<FrameLayout 
    android:id="@+id/fragment_container"
    android:layout_width="0dp"
    android:layout_height="0dp"
    android:layout_marginEnd="0dp"
    android:layout_marginStart="0dp"
    android:background="?android:attr/windowBackground"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
/>

<android.support.design.widget.BottomNavigationView
    android:id="@+id/navigation"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_marginEnd="0dp"
    android:layout_marginStart="0dp"
    android:background="?android:attr/windowBackground"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:menu="@menu/navigation" />
</android.support.constraint.ConstraintLayout>

然后将替换行替换为:

transaction.replace(R.id.fragment_container，片段);

奖励:您可以像这样初始化片段: swiftFragment = new SwiftFragment();

BONUS: You can initiate your fragments like this: swiftFragment = new SwiftFragment();

之后请看一下:实例化新的Android片段的最佳做法

这篇关于带片段的底部导航栏的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！