java - getAdapterPosition() 抛出异常 [android]

Question

我已尽力理解围绕这一问题的问题。我正在创建一个函数，其中涉及编辑 recyclerview 的内容(项目)。它在编辑一行时工作正常，但在 recyclerview 中编辑另一行时抛出 ArrayIndexOutOfBounds 异常。

此代码是错误的根源。

((ClassListOnSetup) context).editClassnameAt(classes.get(getAdapterPosition()).getId(), getAdapterPosition(), classesBean);

我认为 getAdapterPosition() 方法可能会引发此错误:

以下是 editClassnameAt() 方法以供更多引用:

public void editClassnameAt(long id,int position, String classname ){
    demeaSQL.updateAclass(id,classname);

    classListOnSetupRecyclerAdapter.notifyItemChanged(position);
    classListOnSetupRecyclerAdapter.notifyDataSetChanged();
    displayClassList();
}

LogCat 出现错误消息

java.lang.ArrayIndexOutOfBoundsException: length=10; index=-1
at java.util.ArrayList.get(ArrayList.java:413) at com.example.demeainc.demea.ClassListOnSetupRecyclerAdapter$ClassListOnSetupViewHolder$2$2.onClick(ClassListOnSetupRecyclerAdapter.java:87) at android.support.v7.app.AlertController$ButtonHandler.handleMessage(AlertController.java:162)

我哪里错了。有什么帮助吗？

对于那些想查看完整代码的人，
这是我的适配器类完整代码:

public class ClassListOnSetupRecyclerAdapter extends RecyclerView.Adapter<ClassListOnSetupRecyclerAdapter.ClassListOnSetupViewHolder {

    //simple list of classes(mDataSet for Adapter)
    private List<ClassesBean> listClasses;
    private Context mContext;

    public class ClassListOnSetupViewHolder extends RecyclerView.ViewHolder {

        public TextView textView_classname;
        public Button delete_button_classsetup;

        public ClassListOnSetupViewHolder(final Context context, View itemView, final List<ClassesBean> classes) {
            super(itemView);

            textView_classname = itemView.findViewById(R.id.textView_classname);
            delete_button_classsetup = itemView.findViewById(R.id.delete_button_classsetup);

            delete_button_classsetup.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {

                    //  if(view.equals(delete_button_classsetup)) {
                        Log.i("Deletes", "Button pressed");
                        long id = classes.get(getAdapterPosition()).getId();

                        ((ClassListOnSetup) context).removeAt(getAdapterPosition(), classes.get(getAdapterPosition()).getId());
                        Toast.makeText(context, "You Clicked ID = " + id, Toast.LENGTH_SHORT).show();
                }
            });

            itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

                    View promptView = inflater.inflate(R.layout.edit_class, null);

                    AlertDialog.Builder alertDialogueBuilder = new AlertDialog.Builder(mContext);

                    alertDialogueBuilder.setView(promptView);

                    final EditText editText = promptView.findViewById(R.id.edittable_className);
                    editText.setText((listClasses.get(getAdapterPosition()).getClasses_name()));

                    alertDialogueBuilder.setCancelable(false).setPositiveButton("Update", new DialogInterface.OnClickListener() {

                        @Override
                        public void onClick(DialogInterface dialogInterface, int i) {

                            // long id = classes.get(getAdapterPosition()).getId();

                            String classesBean = editText.getText().toString();

                            try {
                                /**This is as a result of trying to find a solution**/
                                //long classesArraySize = classes.size();
                                // while (classes.get(getAdapterPosition()).getId() < classesArraySize) 

                                /**Source of error**/
                                ((ClassListOnSetup) context).editClassnameAt(classes.get(getAdapterPosition()).getId(), getAdapterPosition(), classesBean);
                            } catch (ArrayIndexOutOfBoundsException exception){
                                Log.i("Errore", String.valueOf(exception));
                            }
                        }
                    }).setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialogInterface, int i) {
                            dialogInterface.cancel();
                        }
                    });

                    AlertDialog alert = alertDialogueBuilder.create();
                    alert.show();
                }
            });
        }
    }

    public ClassListOnSetupRecyclerAdapter(Context context, List<ClassesBean> classes){

        mContext = context;
        listClasses = classes;
    }

    @Override
    public ClassListOnSetupRecyclerAdapter.ClassListOnSetupViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        View itemView = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.item_classesname_recycler,parent,false);

        return new ClassListOnSetupViewHolder(mContext,itemView,listClasses);
    }

    @Override
    public void onBindViewHolder(ClassListOnSetupViewHolder holder, final int position) {

        holder.textView_classname.setText(listClasses.get(position).getClasses_name());
    }

    @Override
    public int getItemCount() {
        Log.v(ClassListOnSetupRecyclerAdapter.class.getSimpleName(),"ListClasses"+listClasses.size());
        return listClasses.size();
    }
}

我的 JavaBean 类名为 ClassesBean

public class ClassesBean {

    private Long id;
    private int classes_item_index;
    private String classes_name;
    private String classes_codename;
    private String classes_sections;
    private String classes_teachers;
    private String classes_students;

    public int getClasses_item_index() {

        return classes_item_index;
    }

    public void setClasses_item_index(int classes_item_index) {
        this.classes_item_index = classes_item_index;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getClasses_name() {

        return classes_name;
    }

    public void setClasses_name(String classes_name) {
        this.classes_name = classes_name;
    }

    public String getClasses_codename() {
        return classes_codename;
    }

    public void setClasses_codename(String classes_codename) {
        this.classes_codename = classes_codename;
    }

    public String getClasses_sections() {
        return classes_sections;
    }

    public void setClasses_sections(String classes_sections) {
        this.classes_sections = classes_sections;
    }

    public String getClasses_teachers() {
        return classes_teachers;
    }

    public void setClasses_teachers(String classes_teachers) {
        this.classes_teachers = classes_teachers;
    }

    public String getClasses_students() {
        return classes_students;
    }

    public void setClasses_students(String classes_students) {
        this.classes_students = classes_students;
    }



}

Answer 1

我最初的回答指出，您应该在 onBindViewHolder() 中添加监听器。这可行，但不是最佳解决方案，因为每次调用 onBindViewHolder() 时都会创建新的监听器对象。

在构造函数中添加监听器是正确的，但是 getAdapterPosition() 可以 sometimes返回 -1 (RecyclerView.NO_POSITION)。

解决方案是检查 getAdapterPosition() == RecyclerView.NO_POSITION 是否为 true，如果为 true，则忽略该调用。

 public ClassListOnSetupViewHolder(final Context context, View itemView, final List<ClassesBean> classes) {

    super(itemView);

    delete_button_classsetup = itemView.findViewById(R.id.delete_button_classsetup);

    delete_button_classsetup.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            int adapterPosition = getAdapterPosition();
            if (adapterPosition == RecyclerView.NO_POSITION) {
                return;
            }

            Log.i("Deletes", "Button pressed");
            long id = classes.get(adapterPosition).getId();

            ((ClassListOnSetup) context).removeAt(adapterPosition, classes.get(adapterPosition).getId());
            Toast.makeText(context, "You Clicked ID = " + id, Toast.LENGTH_SHORT).show();
        }
    });

    // ...
 }