所以我今天遇到了一個小問題。我在我的應用程序中創建了一個底部導航視圖,點擊按鈕後,它將替換屏幕上的片段(並且它完美地工作!)。 但啓動應用程序後,並沒有點擊任何按鈕,屏幕上沒有片段。 我意識到只有在點擊按鈕後纔會顯示片段,並且我想要一個默認片段(kalkulatorFragment)。 我已經盡我所能以某種方式設置它,但沒有成功......如何設置主要活動中顯示的默認片段?
public class Main extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
}
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
FragmentManager fm = getFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
kalkulatorFragment kalkulator_fragment = new kalkulatorFragment();
wzoryFragment wzory_fragment = new wzoryFragment();
definicjeFragment definicje_fragment = new definicjeFragment();
switch (item.getItemId()) {
case R.id.kalkulator:
ft.replace(android.R.id.content, kalkulator_fragment);
ft.commit();
return true;
case R.id.wzory:
ft.replace(android.R.id.content, wzory_fragment);
ft.commit();
return true;
case R.id.definicje:
ft.replace(android.R.id.content, definicje_fragment);
ft.commit();
return true;
}
return false;
}
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:design="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/linear"
android:layout_width="match_parent"
android:layout_height="match_parent">
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<fragment
android:id="@+id/definicjeFragment"
android:name="com.thegodofcoding.adamgreloch.ultracalcalpha.definicjeFragment"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"
tools:layout="@layout/definicje_view" />
<fragment
android:id="@+id/wzoryFragment"
android:name="com.thegodofcoding.adamgreloch.ultracalcalpha.wzoryFragment"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"
tools:layout="@layout/wzory_view" />
<fragment
android:id="@+id/kalkulatorFragment"
android:name="com.thegodofcoding.adamgreloch.ultracalcalpha.kalkulatorFragment"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"
tools:layout="@layout/kalkulator_view" />
</FrameLayout>
<android.support.design.widget.BottomNavigationView
android:id="@+id/navigation"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
android:background="@color/bottomNavBar"
android:layout_alignParentBottom="true"
design:menu="@menu/bottom_nav_items" />
謝謝:)