java - 我遇到此错误 java.lang.IndexOutOfBoundsException : Index: 0, 大小:0

Question

我收到错误:

java.lang.IndexOutOfBoundsException: Index: 0, Size: 0

我收到错误的部分是在我的 onBindViewHolder 上的 if 语句中，下面是我的适配器:

public class UserProgramWeekAdapter extends RecyclerView.Adapter<UserProgramWeekAdapter.ViewHolder>{

    private Context context;
    private ArrayList<ProgramTrackerWrapper> programTrackers;



    public UserProgramWeekAdapter(Context context, ArrayList<ProgramTrackerWrapper> programTrackers) {
        this.context = context;
        this.programTrackers = programTrackers;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.activity_user_program_week_adapter, parent, false);
        ViewHolder viewHolder = new ViewHolder(view);
        return viewHolder;

    }

    @Override
    public void onBindViewHolder(UserProgramWeekAdapter.ViewHolder holder, int position) {
        holder.dayTxt.setText(programTrackers.get(position).getDay());
        holder.numberofExercises.setText(programTrackers.get(position).getProgramTrackers().size()+ " exercises");
        boolean isFinished = false;
        for (int i = 0; i < programTrackers.size(); i++){
        if ( programTrackers.get(position).getProgramTrackers().get(i).isProgramExerciseFinished()){
                isFinished = true;
            }
        }
        String statusTxt = isFinished || programTrackers.size() == 0 ? "Completed" : "Not Completed";
        holder.exerciseCompleted.setText(statusTxt);
    }

    @Override
    public int getItemCount() {
        return programTrackers.size();
    }

    public class ViewHolder extends RecyclerView.ViewHolder {

        TextView dayTxt, exerciseCompleted, numberofExercises;

        public ViewHolder(View itemView) {

            super(itemView);

            dayTxt = itemView.findViewById(R.id.dayTxt);
            exerciseCompleted = itemView.findViewById(R.id.exerciseCompleted);
            numberofExercises = itemView.findViewById(R.id.numberofExercises);
        }
    }
}

这是我的 Activity :

public class StartProgramActivity extends AppCompatActivity {

    private Toolbar toolBar;
    private TextView weekTitle, weekStateTxt;
    private ImageView nextBtn, backBtn;
    private Program program;
    private DatabaseReference programTrackerReference;
    private ArrayList<ProgramTracker> allProgramTrackers = new ArrayList<>();
    private ArrayList<ProgramTracker> dayOfWeekExercises = new ArrayList<>();
    private String TAG = "StartProgramActivity";
    private RecyclerView recyclerView;
    private RecyclerView.LayoutManager layoutManager;
    private ArrayList<ProgramTrackerWrapper> programTrackerWrappers = new ArrayList<>();
    private UserProgramWeekAdapter userProgramWeekAdapter;

    private int totalWeeks;
    private int currentWeek = 1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_start_program);
        programTrackerReference = FirebaseDatabase.getInstance().getReference("ProgramTracker");

        getDataFromPreviousActivity();
        getProgramDetails(currentWeek);
        findViews();
    }

    public void getDataFromPreviousActivity(){
        if(getIntent().getSerializableExtra("program") != null) {
            program = (Program) getIntent().getSerializableExtra("program");
            totalWeeks = Integer.parseInt(program.getProgramWeeks());
        }
    }

    private void setUpWeekNavigation(){
        if(currentWeek == 1){
            backBtn.setVisibility(View.GONE);
        }else{
            backBtn.setVisibility(View.VISIBLE);
        }

        if(totalWeeks > 1){
            nextBtn.setVisibility(View.VISIBLE);
        }

        if(currentWeek == totalWeeks){
            nextBtn.setVisibility(View.GONE);
        }
    }

    private void determineWeek(int command){
        // if 0 is passed, meaning back is pressed
        // if 1 is passed, meaning next is pressed

        switch (command){
            case 0:
                currentWeek--;
                weekTitle.setText("Week " + currentWeek);
                setUpWeekNavigation();
                getProgramDetails(currentWeek);
                break;
            case 1:
                currentWeek++;
                weekTitle.setText("Week " + currentWeek);
                setUpWeekNavigation();
                getProgramDetails(currentWeek);
                break;
        }
    }

    private void findViews(){

        toolBar = findViewById(R.id.toolBar);
        setSupportActionBar(toolBar);
        weekTitle = findViewById(R.id.weekTitle);
        weekStateTxt = findViewById(R.id.weekStateTxt);
        nextBtn = findViewById(R.id.nextBtn);
        nextBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Toast.makeText(StartProgramActivity.this, "next", Toast.LENGTH_SHORT).show();
                determineWeek(1);
            }
        });
        backBtn = findViewById(R.id.backBtn);
        backBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Toast.makeText(StartProgramActivity.this, "back", Toast.LENGTH_SHORT).show();
                determineWeek(0);
            }
        });

        setUpWeekNavigation();

        recyclerView = findViewById(R.id.weekExercisesRecycler);
        layoutManager = new LinearLayoutManager(this);
        recyclerView.setLayoutManager(layoutManager);

        for(int i = 0 ; i<7; i++){
            setWeekExercisesData(i);
        }

        userProgramWeekAdapter = new UserProgramWeekAdapter(this,programTrackerWrappers);
        recyclerView.setAdapter(userProgramWeekAdapter);
    }

    public void getProgramDetails(int week){
        allProgramTrackers = new ArrayList<>();
        programTrackerReference
                .child(GlobalUser.getmUser().getiD())
                .child(program.getProgramsId()).addChildEventListener(new ChildEventListener() {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String s) {
                ProgramTracker programTracker = dataSnapshot.getValue(ProgramTracker.class);
            // Log.d("Progra")
                if(programTracker.getWeek() == (week-1)) {
                    allProgramTrackers.add(programTracker);

                }
            }

            @Override
            public void onChildChanged(DataSnapshot dataSnapshot, String s) {

            }

            @Override
            public void onChildRemoved(DataSnapshot dataSnapshot) {

            }

            @Override
            public void onChildMoved(DataSnapshot dataSnapshot, String s) {

            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });
    }

    public void setWeekExercisesData(int position){
        switch (position){
            case 0:
                dayOfWeekExercises = new ArrayList<>();
                for (int i = 0; i<allProgramTrackers.size(); i++){
                    if(allProgramTrackers.get(i).getDay().equals("Monday")){
                        dayOfWeekExercises.add(allProgramTrackers.get(i));
                    }
                }
                ProgramTrackerWrapper programTrackerWrapper = new ProgramTrackerWrapper("Monday", allProgramTrackers);
                programTrackerWrappers.add(programTrackerWrapper);
                Log.d(TAG, "DayOfWeekExercises: " + dayOfWeekExercises.toString());
                break;
            case 1:
                dayOfWeekExercises = new ArrayList<>();
                for (int i = 0; i<allProgramTrackers.size(); i++){
                    if(allProgramTrackers.get(i).getDay().equals("Tuesday")){
                        dayOfWeekExercises.add(allProgramTrackers.get(i));
                    }
                }
                ProgramTrackerWrapper programTrackerWrapper1 = new ProgramTrackerWrapper("Tuesday", allProgramTrackers);
                programTrackerWrappers.add(programTrackerWrapper1);
                Log.d(TAG, "DayOfWeekExercises: " + dayOfWeekExercises.toString());
                break;
            case 2:
                dayOfWeekExercises = new ArrayList<>();
                for (int i = 0; i<allProgramTrackers.size(); i++){
                    if(allProgramTrackers.get(i).getDay().equals("Wednesday")){
                        dayOfWeekExercises.add(allProgramTrackers.get(i));
                    }
                }
                ProgramTrackerWrapper programTrackerWrapper2 = new ProgramTrackerWrapper("Wednesday", allProgramTrackers);
                programTrackerWrappers.add(programTrackerWrapper2);
                Log.d(TAG, "DayOfWeekExercises: " + dayOfWeekExercises.toString());
                break;
            case 3:
                dayOfWeekExercises = new ArrayList<>();
                for (int i = 0; i<allProgramTrackers.size(); i++){
                    if(allProgramTrackers.get(i).getDay().equals("Thursday")){
                        dayOfWeekExercises.add(allProgramTrackers.get(i));
                    }
                }
                ProgramTrackerWrapper programTrackerWrapper3 = new ProgramTrackerWrapper("Thursday", allProgramTrackers);
                programTrackerWrappers.add(programTrackerWrapper3);
                Log.d(TAG, "DayOfWeekExercises: " + dayOfWeekExercises.toString());
                break;
            case 4:
                dayOfWeekExercises = new ArrayList<>();
                for (int i = 0; i<allProgramTrackers.size(); i++){
                    if(allProgramTrackers.get(i).getDay().equals("Friday")){
                        dayOfWeekExercises.add(allProgramTrackers.get(i));
                    }
                }
                ProgramTrackerWrapper programTrackerWrapper4 = new ProgramTrackerWrapper("Friday", allProgramTrackers);
                programTrackerWrappers.add(programTrackerWrapper4);
                Log.d(TAG, "DayOfWeekExercises: " + dayOfWeekExercises.toString());
                break;
            case 5:
                dayOfWeekExercises = new ArrayList<>();
                for (int i = 0; i<allProgramTrackers.size(); i++){
                    if(allProgramTrackers.get(i).getDay().equals("Saturday")){
                        dayOfWeekExercises.add(allProgramTrackers.get(i));
                    }
                }
                ProgramTrackerWrapper programTrackerWrapper5 = new ProgramTrackerWrapper("Saturday", allProgramTrackers);
                programTrackerWrappers.add(programTrackerWrapper5);
                Log.d(TAG, "DayOfWeekExercises: " + dayOfWeekExercises.toString());
                break;
            case 6:
                dayOfWeekExercises = new ArrayList<>();
                for (int i = 0; i<allProgramTrackers.size(); i++){
                    if(allProgramTrackers.get(i).getDay().equals("Sunday")){
                        dayOfWeekExercises.add(allProgramTrackers.get(i));
                    }
                }
                ProgramTrackerWrapper programTrackerWrapper6 = new ProgramTrackerWrapper("Sunday", allProgramTrackers);
                programTrackerWrappers.add(programTrackerWrapper6);
                Log.d(TAG, "DayOfWeekExercises: " + dayOfWeekExercises.toString());
                break;
        }
    }

    public ArrayList<ProgramTracker> getDayOfWeekExercises() {
        return dayOfWeekExercises;
    }
}

Answer 1

这看起来很可疑:

for (int i = 0; i < programTrackers.size(); i++){
  if ( programTrackers.get(position).getProgramTrackers().get(i).isProgramExerciseFinished()){
        isFinished = true;
    }
}

您检查了 programTrackers 列表的大小，但没有检查其子列表，因此 i 很容易指向不正确的索引:

final int sublistSize =  programTrackers.get(position).getProgramTrackers().size();
for (int i = 0; i < sublistSize; i++){
  if (programTrackers.get(position).getProgramTrackers().get(i).isProgramExerciseFinished()){
        isFinished = true;
    }
}