安卓:创建 Recyclerview

Question

我是 android 开发的新手，我正在尝试使用 RecyclerView。我遵循了一些教程和 Google 文档，但当我尝试在我的 Activity Courses_Adapter 中使用适配器时，总是会发生同样的错误。

adapter = new Courses_Adapter(courseList); courseList 中的错误

主要 Activity

public class Courses extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.courses_layout);

        RecyclerView rv = (RecyclerView) findViewById(R.id.my_recycler_view);

        rv.setHasFixedSize(true);

        // use a linear layout manager
        LinearLayoutManager llm = new LinearLayoutManager(this);
        rv.setLayoutManager(llm);

        Courses_Adapter adapter = new Courses_Adapter(courseList);
        rv.setAdapter(adapter);

    }
}

---

适配器

public class Courses_Adapter extends RecyclerView.Adapter<Courses_Adapter.Course> {

    @Override
    public Course onCreateViewHolder(ViewGroup viewGroup, int viewType) {

        View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.course_layout, viewGroup, false);

        return new Course(view);
    }

    @Override
    public void onBindViewHolder(Course itemViewHolder, int position) {

        Course.courseName.setText(courseList.get(position).course);
    }

    @Override
    public int getItemCount() {

        return courseList.size();
    }

    public static class Course extends RecyclerView.ViewHolder {

        CardView cv;
        static TextView courseName;

        public Course(View itemView) {

            super(itemView);
            cv = (CardView)itemView.findViewById(R.id.cv);
            courseName = (TextView)itemView.findViewById(R.id.courseName);
        }
    }

    List<course> courseList;

    Courses_Adapter(List<course> courseList){

        this.courseList=courseList;
    }

    @Override
    public void onAttachedToRecyclerView(RecyclerView recyclerView) {
        super.onAttachedToRecyclerView(recyclerView);
    }

}

---

元素等级

public class course {
    String course;

    course(String course){

        this.course = course;
    }

    private List<course> courseList;

    private void initializeData(){
        courseList = new ArrayList<>();
        courseList.add(new course("Math 1"));
        courseList.add(new course("Math 2"));
        courseList.add(new course("Physics 1"));
    }
}

Answer 1

你错过了这个:

List<course> courseList = new ArrayList<>();

之前

Courses_Adapter adapter = new Courses_Adapter(courseList);