Question

一切正常，我从未遇到任何问题。但不知何故，当我尝试接收不在第一个位置的Tab时，我现在得到一个空对象：

java.lang.NullPointerException：尝试调用虚方法＆＃39; android.support.design.widget.TabLayout $ Tab android.support.design.widget.TabLayout $ Tab.setCustomView（android.view.View）＆＃39;在空对象引用上

在onCreateView中调用tabLayoutSetup。

 private void tabLayoutSetup(){
    // Get the ViewPager and set it's PagerAdapter so that it can display items
    Bugger.t(context,"tablayout");
    viewPager.setAdapter(pagerAdapter);
    // Give the TabLayout the ViewPager
    tabLayout.setupWithViewPager(viewPager);
     createTabs();

}

//this method is creating all tabs for account's tablayout
private void createTabs(){
    TabLayout.Tab ShareTab = tabLayout.getTabAt(0);
    TabLayout.Tab MarkTab = tabLayout.getTabAt(1);

    //***********************************************************************************************************
    //inflating template for first tab, Activities.
    View TabView = LayoutInflater.from(context).inflate(R.layout.account_tablayout_customtab, null); //template
    TextView titel = (TextView) TabView.findViewById(R.id.tab_titel);
    //populating first template for 'Activities'
    titel.setText(getResources().getString(R.string.SharesTab));
    titel.setTextColor(ContextCompat.getColor(context,R.color.tabLayout_active));
    ShareTab.setCustomView(TabView);

    //**********************************************************************************************************
    //inflating template for second tab, Messages.
    TabView = LayoutInflater.from(context).inflate(R.layout.account_tablayout_customtab, null); //template
    titel = (TextView) TabView.findViewById(R.id.tab_titel);
    //populating second template for 'Messages'
    titel.setText(getResources().getString(R.string.MarkTab));
    MarkTab.setCustomView(TabView);

这真的很奇怪，因为它之前运作顺利。在位置0（.getTabAt(0)）接收选项卡根本不是问题。但是，我无法在第一个位置收到Tab。

XML：

<android.support.design.widget.TabLayout
            android:id="@+id/account_tabLayout"
            android:layout_width="match_parent"
            android:layout_height="52dp"
            android:layout_marginTop="12dp"
            android:visibility="visible"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/account_bio">


        </android.support.design.widget.TabLayout>

Answer 1

您需要添加TabItems。您可以在Layout XML中执行此操作。像这样：

<android.support.design.widget.TabLayout
            android:id="@+id/account_tabLayout"
            android:layout_width="match_parent"
            android:layout_height="52dp"
            android:layout_marginTop="12dp"
            android:visibility="visible"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/account_bio">

            <android.support.design.widget.TabItem
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@string/button_menu"
                />

            <android.support.design.widget.TabItem
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@string/button_favorites"
                />


        </android.support.design.widget.TabLayout>

您应该能够为每个人TabItem一个身份android:id="@+id/tabItemX1"并直接访问它，而不是使用.getTabAt(0)

TabLayout.getTabAt（）返回null对象

1 个答案: