Android RecycleView为空。我错过了什么?
我不明白我的准备方法遗漏了什么。Main活动开始,但我的RecycleView为空。在MainActivity的开始部分,我有问题和单选按钮,当时间用完或按下“确认/下一步”按钮时,下一个问题和选项正在加载。我决定尝试使用RecycleView和卡片在MainActivity中一次加载所有问题 公共类MainActivity扩展了AppCompatActivity{Android RecycleView为空。我错过了什么?,android,android-recyclerview,onclicklistener,oncheckedchanged,Android,Android Recyclerview,Onclicklistener,Oncheckedchanged,我不明白我的准备方法遗漏了什么。Main活动开始,但我的RecycleView为空。在MainActivity的开始部分,我有问题和单选按钮,当时间用完或按下“确认/下一步”按钮时,下一个问题和选项正在加载。我决定尝试使用RecycleView和卡片在MainActivity中一次加载所有问题 公共类MainActivity扩展了AppCompatActivity{ private QuestionAdapter adapter; private ArrayList<Question>
private QuestionAdapter adapter;
private ArrayList<Question> questionList;
private int questionCountTotal;
private long backPressedTime;
public QuizDbHelper dbHelper;
RecyclerView recyclerView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recyclerView = findViewById(R.id.recycler_view);
questionList = new ArrayList<>();
adapter = new QuestionAdapter(this, questionList);
RecyclerView.LayoutManager mLayoutManager = new GridLayoutManager(this, 1);
recyclerView.setLayoutManager(mLayoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setAdapter(adapter);
dbHelper = new QuizDbHelper(this);
questionList = dbHelper.getAllQuestions();
questionCountTotal = questionList.size();
Collections.shuffle(questionList);
prepareQuestion();
}
private void prepareQuestion() {
//Tried different things here. Maybe problem is somewhere else?
Question q = new Question();
questionList.add(q);
// questionList.addAll(dbHelper.getAllQuestions());
adapter.notifyDataSetChanged();
}
}
专用适配器;
私人ArrayList问题列表;
私人总人数;
私人长时间背压;
公共QuizDbHelper数据库助手;
回收视图回收视图;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recyclerView=findViewById(R.id.recycler\u视图);
questionList=新的ArrayList();
adapter=新的QuestionAdapter(此,questionList);
RecyclerView.LayoutManager mLayoutManager=新的GridLayoutManager(这个,1);
recyclerView.setLayoutManager(mLayoutManager);
setItemAnimator(新的DefaultItemAnimator());
recyclerView.setAdapter(适配器);
dbHelper=新的QuizDbHelper(本);
questionList=dbHelper.getAllQuestions();
questionCountTotal=questionList.size();
收集。洗牌(问题列表);
prepareQuestion();
}
私有无效准备(){
//在这里尝试了不同的方法。也许问题出在其他地方?
问题q=新问题();
问题列表。添加(q);
//addAll(dbHelper.getAllQuestions());
adapter.notifyDataSetChanged();
}
}
这是我的问题
public class QuestionAdapter extends RecyclerView.Adapter<QuestionAdapter.MyViewHolder> {
private ArrayList<Question> questionList;
public class MyViewHolder extends RecyclerView.ViewHolder {
public TextView tvQuestion, tvScore, tvQuestionCount, tvCountdown;
public RadioGroup rbGroup;
public RadioButton rb1, rb2, rb3, rb4;
public MyViewHolder(View view) {
super(view);
tvQuestion = view.findViewById(R.id.question);
tvScore = view.findViewById(R.id.score);
tvQuestionCount = view.findViewById(R.id.question_count);
tvCountdown = view.findViewById(R.id.count_down);
rbGroup = view.findViewById(R.id.radiog_group);
rb1 = view.findViewById(R.id.radio_button1);
rb2 = view.findViewById(R.id.radio_button2);
rb3 = view.findViewById(R.id.radio_button3);
rb4 = view.findViewById(R.id.radio_button4);
}
}
public QuestionAdapter(Context mContext, ArrayList<Question> questionList) {
this.questionList = questionList;
}
@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext())
.inflate(R.layout.question_card, parent, false);
return new MyViewHolder(itemView);
}
@Override
public void onBindViewHolder(final MyViewHolder holder, int position) {
Question question = questionList.get(position);
holder.tvQuestion.setText(question.getQuestion());
holder.rb1.setText(question.getOption1());
holder.rb2.setText(question.getOption2());
holder.rb3.setText(question.getOption3());
holder.rb4.setText(question.getOption4());
}
@Override
public int getItemCount() {
return questionList.size();
公共类QuestionAdapter扩展了RecyclerView.Adapter{
私人ArrayList问题列表;
公共类MyViewHolder扩展了RecyclerView.ViewHolder{
公共文本查看电视问题、电视分数、电视问题计数、电视倒计时;
公共放射组;
公共单选按钮rb1、rb2、rb3、rb4;
公共MyViewHolder(视图){
超级(视图);
tvQuestion=view.findviewbyd(R.id.question);
tvScore=view.findViewById(R.id.score);
tvQuestionCount=view.findViewById(R.id.question\u计数);
tvCountdown=view.findviewbyd(R.id.countdown);
rbGroup=view.findViewById(R.id.RATIO_组);
rb1=view.findViewById(R.id.radio_按钮1);
rb2=view.findViewById(R.id.radio_按钮2);
rb3=view.findViewById(R.id.radio_按钮3);
rb4=view.findViewById(R.id.radio_按钮4);
}
}
公共问题适配器(上下文mContext、ArrayList问题列表){
this.questionList=问题列表;
}
@凌驾
公共MyViewHolder onCreateViewHolder(视图组父级,int-viewType){
View itemView=LayoutInflater.from(parent.getContext())
.充气(R.layout.question_卡,家长,假);
返回新的MyViewHolder(itemView);
}
@凌驾
公共无效onBindViewHolder(最终MyViewHolder,内部位置){
问题=问题列表。获取(位置);
holder.tvQuestion.setText(question.getQuestion());
holder.rb1.setText(question.getOption1());
holder.rb2.setText(question.getOption2());
holder.rb3.setText(question.getOption3());
holder.rb4.setText(question.getOption4());
}
@凌驾
public int getItemCount(){
返回questionList.size();
要一次加载所有问题,您应该在活动中获取这些问题并将其添加到问题列表中
questionList.addAll(dbHelper.getAllQuestions());
adapter.notifyDataSetChanged();//to refresh view and show items ;-)
如果要在适配器定义中获取click listener,可以在preparequestion()方法中使用侦听器
更改适配器。notifyDataSetChanged();
到
感谢您的回复。我对问题做了一些更改,试图简化问题,目前只指出一个问题。我的活动为空,RecycleView没有从数据库中填充问题。adapter=新问题适配器(getApplicationContext(),questionList);RecycleView.setAdapter(adapter)非常感谢,它成功了。
adapter = new QuestionAdapter (getActivity(), questionList);
recyclerView.setAdapter(adapter);