关于 ake sure class name exists, is public, and has an empty constructor that is public

解决方法：自定义的fragment最好有一个Public的参数为空的构造函数，若需要传入一个参数，可以使用下面的方法
public FileViewFragment(){    }
 public static FileViewFragment getInstance(A a){
        FileViewFragment fileViewFragment = new FileViewFragment();
        fileViewFragment.a = a;
        return fileViewFragment;
    }