java - 如何动态更改ActionBar中的图标

Question

我想动态更改ActionBar上的图标，我有一个退出菜单。但它不会改变我的Android手机5版本

public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.exit_menu, menu);
        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle item selection
        switch (item.getItemId()) {
            case R.id.exit_menu:
                android.os.Process.killProcess(android.os.Process.myPid());
                System.exit(1);
                return true;

            default:
                return super.onOptionsItemSelected(item);
        }
    }

This is my exit menu xml.

 <menu xmlns:android="http://schemas.android.com/apk/res/android">
            <item android:id="@+id/exit_menu"
                android:icon="@drawable/exit"
                android:title="Exit"
               />       
        </menu>

Answer 1

编辑2:在onCreateOptionsMenu(Menu菜单)

MenuItem menuItem=menu.findItem(R.id.exit_menu);
MenuItemCompat.getActionView(menuItem);
menuItem.setIcon(R.drawable.new_icon);

xml:

<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto" >
    <item
        android:id="@+id/exit_menu"
        android:title="@string/menu_string"
        android:icon="@drawable/exit"
        app:showAsAction="always"/>
</menu>