从自定义适配器更新menuItem图标

如果要通过单击定制适配器来更新菜单项，则可以创建全局菜单对象以在整个活动/片段中访问它。我们假设认为为什么我们不应该使用findViewById（R.id）访问菜单项。您不能将findViewById用于菜单项。简而言之，您可以按照以下步骤操作。

1. 创建菜单对象。

   私人菜单mMenu;

2. 在您的onCreateOptionsMenu（）中

   this.menu =菜单;

3. 在“自定义适配器收藏夹”按钮中，单击事件。

   menu.getItem（0）.setIcon（getResources（）。getDrawable（R.drawable.ic_launcher））;;

例如 ：

package test.actionbariconupdate;

import android.app.Activity;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ImageView;


public class ActionBarIconUpdate extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_action_bar_icon_update2);
        if (savedInstanceState == null) {
            getFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment())
                    .commit();
        }
    }


    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {

        private Menu mMenu;
        private Button buttonclick;

        public PlaceholderFragment() {
        }

        @Override
        public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
            inflater.inflate(R.menu.menu_action_bar_icon_update, menu);
            this.mMenu = menu;
            super.onCreateOptionsMenu(menu, inflater);

        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            setHasOptionsMenu(true);
            View rootView = inflater.inflate(R.layout.fragment_action_bar_icon_update, container, false);
            buttonclick = (Button)rootView.findViewById(R.id.buttonclick);
            buttonclick.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    if(mMenu != null){
                        ImageView imageView  = (ImageView) mMenu.getItem(0).getActionView().findViewById(R.id.menu_icon);
                        imageView.setBackground(getResources().getDrawable(R.drawable.icon));
                    }
                }
            });
            return rootView;
        }
    }
}

menu_action_bar_icon_update.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    >
    <item
        android:id="@+id/action_settings"
        android:title="@string/action_settings"
        android:showAsAction="always"
        android:actionLayout="@layout/action_menu"/>
</menu>

@ layout / action_menu.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:id="@+id/menu_icon"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/ic_launcher" />
</LinearLayout>

我运行此代码，便能够动态更改图标。希望对您有帮助。