Options Menu菜单选项

xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
       xmlns:app="http://schemas.android.com/apk/res-auto">
    <item
        android:id="@+id/one"
        android:title="listView"
        app:showAsAction="never">
    </item>
    <item
        android:id="@+id/two"
        android:title="GridView"
        app:showAsAction="ifRoom">
    </item>
    <item
        android:id="@+id/three"
        android:title="瀑布流"
        app:showAsAction="always">

    </item>
</menu>

MainActivity'

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.item,menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
        switch(item.getItemId()){
                case R.id.one:
                 rv.setLayoutManager(new LinearLayoutManager(MainActivity.this));
                break;
                case R.id.two:
                    rv.setLayoutManager(new GridLayoutManager(MainActivity.this,2));
                break;
                case R.id.three:
                    rv.setLayoutManager(new StaggeredGridLayoutManager(2,StaggeredGridLayoutManager.VERTICAL));
                break;
            }
    return super.onOptionsItemSelected(item);
}