片段未加载底部导航视图

时间:2018-04-21 11:00:02

标签: java android xml

嗨我正在制作应用程序,我使用底部导航来浏览片段,但我的问题是当我点击应用程序加载片段在框架布局中不可见,甚至当我点击底部导航它只是显示空白页面 下面是我的主要活动代码 我在谷歌搜索这个问题,但看起来我是唯一一个有这个问题的人

 public class MainActivity extends AppCompatActivity implements BottomNavigationView.OnNavigationItemSelectedListener{
       FrameLayout frameLayout;
       FragmentManager fragmentManager;
       Fragment fragment;
       BottomNavigationView bottomNavigationView;


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


        fragmentManager = getSupportFragmentManager();

        if(findViewById(R.id.frame_container)!=null){
            if(savedInstanceState!=null){

                return;
            }

        }
        bottomNavigationView = (BottomNavigationView) findViewById(R.id.bottom_nav);
        //bottomNavigationView.setOnNavigationItemSelectedListener(this);
        //final SeekBar sb = (SeekBar) findViewById(R.id.sb);

    }


    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
        Fragment fragment = null;
        switch (item.getItemId()){
            case R.id.navigation_home:
                fragment = new HomeFragment();
                loadFragment(fragment);
                return true;
            case R.id.navigation_feed:
                fragment = new FeedFragment();
                loadFragment(fragment);
                return true;
            case R.id.navigation_event:
                fragment = new EventsFragment();
                loadFragment(fragment);
                return true;
            case R.id.navigation_nearby:
                fragment = new NearbyFragment();
                loadFragment(fragment);
                return true;
            case R.id.navigation_profile:
                fragment = new ProfileFragment();
                loadFragment(fragment);
                return true;
        }

        return false;
    }


    private void loadFragment(Fragment fragment) {
        // load fragment
        //HomeFragment homeFragment = new HomeFragment();
        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
        transaction.replace(R.id.frame_container, fragment,null);
       // transaction.addToBackStack(null);
      /* Comment this line and it should work!*/
        //transaction.addToBackStack(null);
        transaction.commit();
    }

}

和我的xml

<LinearLayout android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:fillViewport="true"
    android:fitsSystemWindows="true"
    android:orientation="vertical"
    xmlns:android="http://schemas.android.com/apk/res/android">

<FrameLayout
    android:id="@+id/frame_container"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="1">

</FrameLayout>
    <android.support.design.widget.BottomNavigationView
        android:id="@+id/bottom_nav"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:menu="@menu/navigation"
        android:backgroundTint="@color/nav_color"
        app:itemIconTint="@color/bottom_nav_fore_color"
        android:background="?android:attr/windowBackground"
        android:layout_weight="0.1">

    </android.support.design.widget.BottomNavigationView>
</LinearLayout>

2 个答案:

答案 0 :(得分:0)

您的代码似乎正确,取消注释此行,然后检查:

  bottomNavigationView.setOnNavigationItemSelectedListener
                (new BottomNavigationView.OnNavigationItemSelectedListener() {
                    @Override
                    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                        Fragment selectedFragment = null;
                        switch (item.getItemId()) {
                            case R.id.action_item1:
                                selectedFragment = ItemOneFragment.newInstance();
                                break;
                            case R.id.action_item2:
                                selectedFragment = ItemTwoFragment.newInstance();
                                break;
                            case R.id.action_item3:
                                selectedFragment = ItemThreeFragment.newInstance();
                                break;
                        }
                        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
                        transaction.replace(R.id.frame_container, selectedFragment);
                        transaction.commit();
                        return true;
                    }
                });

希望这有帮助!

删除它:

implements BottomNavigationView.OnNavigationItemSelectedListener

答案 1 :(得分:0)

您没有设置您的setOnNavigationItemSelectedListener表示您没有将片段设置到底部导航抽屉,说明没有片段正在查看的原因。

首先将setOnNavigationItemSelectedListener添加到bottomnavigation

        bottomNavigationView.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);   

然后添加此代码 - :

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

    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
     Fragment fragment=null;
        switch (item.getItemId()) {
           case R.id.navigation_home:
            fragment = new HomeFragment();
            loadFragment(fragment);
            return true;
        case R.id.navigation_feed:
            fragment = new FeedFragment();
            loadFragment(fragment);
            return true;
        case R.id.navigation_event:
            fragment = new EventsFragment();
            loadFragment(fragment);
            return true;
        case R.id.navigation_nearby:
            fragment = new NearbyFragment();
            loadFragment(fragment);
            return true;
        case R.id.navigation_profile:
            fragment = new ProfileFragment();
            loadFragment(fragment);
            return true;
        }
        return false;
    }
};