如何将MenuItem投射到LinearLayout [英] How to cast MenuItem to LinearLayout

问题描述

我有NavigationView菜单. 我可以使用

从navigationView获取MenuItem

I have NavigationView with menus. I am able to get MenuItem from navigationView by using

MenuItem menuItem = navigationView.getMenu().getItem(0);
LinearLayout linearLayout = (LinearLayout) menuItem; 

我想将menuItem投射到LinearLayout或视图".

I want to cast menuItem to LinearLayout or View.

我已经在menu.xml中将android:actionViewClass设置为menu:

I have set android:actionViewClass to menu in menu.xml :

 <item
    android:id="@+id/nav_backup"
    android:icon="@drawable/ic_sd_card_black_24dp"
    android:actionViewClass="android.widget.LinearLayout"
    android:title="@string/backup_configuration" />

在投射时，我面对NullPointerException.我该如何投放?

While casting I am facing NullPointerException. How can I cast this?

推荐答案

首先尝试对您的MenuItem设置自定义布局，而不是像下面的代码一样将其强制转换为LinearLayout

Try this first set custom layout to your MenuItem than cast it to LinearLayout like below code

MenuItem item = menu.findItem(R.id.action_cart);
MenuItemCompat.setActionView(item, R.layout.menu_layout);
LinearLayout linearLayout = (LinearLayout) MenuItemCompat.getActionView(item);

编辑

直接使用 MenuItem.setActionView() 和 MenuItem.getActionView()

Direct use MenuItem.setActionView() and MenuItem.getActionView()

示例代码

 @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuItem item = menu.findItem(R.id.action_menu);
        item.setActionView( R.layout.activity_main);
        LinearLayout linearLayout = (LinearLayout) item.getActionView();
        return super.onCreateOptionsMenu(menu);
    }

这篇关于如何将MenuItem投射到LinearLayout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！