Android 片段事务问题（默认片段显示两次）

我正在使用底部栏处理片段事务。在我的应用程序中，默认的片段显示两次，当选择第二个片段时，它不会隐藏

public class MainActivity extends AppCompatActivity {
private Fragment fragment;
private FragmentManager fragmentManager;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    fragmentManager = getSupportFragmentManager();
    fragment = new FragmentOne();
    final FragmentTransaction transaction = fragmentManager.beginTransaction();
    transaction.add(R.id.output, fragment).commit();


    BottomBar bottomBar = (BottomBar) findViewById(R.id.bottomBar);
    bottomBar.setOnTabSelectListener(new OnTabSelectListener() {
        @Override
        public void onTabSelected(@IdRes int tabId) {
            switch (tabId){
                case R.id.tab_favorites:
                    Toast.makeText(MainActivity.this, "FAV", Toast.LENGTH_SHORT).show();
                    fragment = new FragmentOne();
                    break;
                case R.id.tab_friends:
                    Toast.makeText(MainActivity.this, "FRIEND", Toast.LENGTH_SHORT).show();
                    fragment = new FragmentTwo();
                    break;
                case R.id.tab_nearby:
                    Toast.makeText(MainActivity.this, "NEAR", Toast.LENGTH_SHORT).show();
                    fragment = new FragmentOne();
                    break;
                case R.id.tab_test:
                    Toast.makeText(MainActivity.this, "TEST", Toast.LENGTH_SHORT).show();
                    fragment = new FragmentTwo();
                    break;
            }
            final FragmentTransaction transaction = fragmentManager.beginTransaction();
            transaction.replace(R.id.output, fragment).commit();
        }
    });

    bottomBar.setOnTabReselectListener(new OnTabReselectListener() {
        @Override
        public void onTabReSelected(@IdRes int tabId) {
        }
    });
}

请帮我解决这个问题 这是我的xml布局

    <?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:id="@+id/activity_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context="com.syntax.bottomtabs.MainActivity">
<fragment
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginTop="10dp"
        android:layout_marginBottom="10dp"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp"
        android:name="com.syntax.bottomtabs.FragmentOne"
        android:id="@+id/output"/>

    <com.roughike.bottombar.BottomBar
        android:id="@+id/bottomBar"
        android:layout_width="match_parent"
        android:layout_height="70dp"
        android:layout_alignParentBottom="true"
        app:bb_tabXmlResource="@xml/bottombar_tabs_three" />
</RelativeLayout>

---

只需通过使用相对布局替换片段来替换xml，如下所示

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.syntax.bottomtabs.MainActivity">
<RelativeLayout 
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_marginTop="10dp"
    android:layout_marginBottom="10dp"
    android:layout_marginLeft="10dp"
    android:layout_marginRight="10dp"
    android:id="@+id/output">
</RelativeLayout>

<com.roughike.bottombar.BottomBar
    android:id="@+id/bottomBar"
    android:layout_width="match_parent"
    android:layout_height="70dp"
    android:layout_alignParentBottom="true"
    app:bb_tabXmlResource="@xml/bottombar_tabs_three" />
</RelativeLayout>

---

希望它能有所帮助……

不要添加片段。添加一个容器，然后用片段替换它。在这里，framelayout将用作容器

您的xml代码应该是：

<?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:id="@+id/activity_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context="com.syntax.bottomtabs.MainActivity">

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

    <com.roughike.bottombar.BottomBar
        android:id="@+id/bottomBar"
        android:layout_width="match_parent"
        android:layout_height="70dp"
        android:layout_alignParentBottom="true"
        app:bb_tabXmlResource="@xml/bottombar_tabs_three" />
</RelativeLayout>

代码的其余部分：

bottomBar.setOnTabSelectListener(new OnTabSelectListener() {
        final FragmentManager fm = getFragmentManager();
        @Override
        public void onTabSelected(@IdRes int tabId) {
            switch (tabId){
                case R.id.tab_favorites:
                    Toast.makeText(MainActivity.this, "FAV", Toast.LENGTH_SHORT).show();
                    fm.beginTransaction().replace(R.id.content_frame, new FragmentOne()).commit();
                    break;
                case R.id.tab_friends:
                    Toast.makeText(MainActivity.this, "FRIEND", Toast.LENGTH_SHORT).show();
                    fm.beginTransaction().replace(R.id.content_frame, new FragmentTwo()).commit();
                    break;
                case R.id.tab_nearby:
                    Toast.makeText(MainActivity.this, "NEAR", Toast.LENGTH_SHORT).show();
                    fm.beginTransaction().replace(R.id.content_frame, new FragmentOne()).commit();
                    break;
                case R.id.tab_test:
                    Toast.makeText(MainActivity.this, "TEST", Toast.LENGTH_SHORT).show();
                    fm.beginTransaction().replace(R.id.content_frame, new FragmentTwo()).commit();
                    break;
            }
        }
    });

---

也给我们您的xml代码

bottomBar.setOnTabSelectListener(new OnTabSelectListener() {
        final FragmentManager fm = getFragmentManager();
        @Override
        public void onTabSelected(@IdRes int tabId) {
            switch (tabId){
                case R.id.tab_favorites:
                    Toast.makeText(MainActivity.this, "FAV", Toast.LENGTH_SHORT).show();
                    fm.beginTransaction().replace(R.id.content_frame, new FragmentOne()).commit();
                    break;
                case R.id.tab_friends:
                    Toast.makeText(MainActivity.this, "FRIEND", Toast.LENGTH_SHORT).show();
                    fm.beginTransaction().replace(R.id.content_frame, new FragmentTwo()).commit();
                    break;
                case R.id.tab_nearby:
                    Toast.makeText(MainActivity.this, "NEAR", Toast.LENGTH_SHORT).show();
                    fm.beginTransaction().replace(R.id.content_frame, new FragmentOne()).commit();
                    break;
                case R.id.tab_test:
                    Toast.makeText(MainActivity.this, "TEST", Toast.LENGTH_SHORT).show();
                    fm.beginTransaction().replace(R.id.content_frame, new FragmentTwo()).commit();
                    break;
            }
        }
    });