活动中添加menu出现错误

FirstActivity中,重写onCreateOptionsMenu()和OnOptionsItemSelected()方法：

全选复制放进笔记
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

public boolean onOptionsItemSelected(MenuItem item){
    switch (item.getItemId()) {
    case R.id.add_item:
        Toast.makeText(this, "You clicked Add", Toast.LENGTH_SHORT).show();
        break;
    case R.id.remove_item:
        Toast.makeText(this, "You clicked Remove", Toast.LENGTH_SHORT).show();
        break;
    default:
    }
    return true;
}

出现错误：需要class,interface或enum