ClassCastException:String cannot be cast to

0
votes

I have an error in my code.

logcat:

java.lang.ClassCastException: java.lang.String cannot be cast to com.example.aymen.schoolmanager.dates at com.example.aymen.schoolmanager.Adapter.onBindViewHolder(Adapter.java:68) at com.example.aymen.schoolmanager.Adapter.onBindViewHolder(Adapter.java:20) at android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:6356) at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6389) at android.support.v7.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5335) at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:5598) at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5440) at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5436) at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2224) at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1551) at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1511) at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:595) at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3583) at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3312) at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3844) at android.view.View.layout(View.java:17637) at android.view.ViewGroup.layout(ViewGroup.java:5575) at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1079) at android.view.View.layout(View.java:17637) at android.view.ViewGroup.layout(ViewGroup.java:5575) at android.support.v4.view.ViewPager.onLayout(ViewPager.java:1795) at android.view.View.layout(View.java:17637) at android.view.ViewGroup.layout(ViewGroup.java:5575) at android.support.design.widget.HeaderScrollingViewBehavior.layoutChild(HeaderScrollingViewBehavior.java:131) at android.support.design.widget.ViewOffsetBehavior.onLayoutChild(ViewOffsetBehavior.java:42) at android.support.design.widget.AppBarLayout$ScrollingViewBehavior.onLayoutChild(AppBarLayout.java:1391) at android.support.design.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:870) at android.view.View.layout(View.java:17637) at android.view.ViewGroup.layout(ViewGroup.java:5575) at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323) at android.widget.FrameLayout.onLayout(FrameLayout.java:261) at android.view.View.layout(View.java:17637) at android.view.ViewGroup.layout(ViewGroup.java:5575) at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741) at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585) at android.widget.LinearLayout.onLayout(LinearLayout.java:1494) at android.view.View.layout(View.java:17637) at android.view.ViewGroup.layout(ViewGroup.java:5575) at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323) at android.widget.FrameLayout.onLayout(FrameLayout.java:261) at android.view.View.layout(View.java:17637) at android.view.ViewGroup.layout(ViewGroup.java:5575) at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741) at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585) at android.widget.LinearLayout.onLayout(LinearLayout.java:1494) at android.view.View.layout(View.java:17637) at android.view.ViewGroup.layout(ViewGroup.java:5575) at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323) at android.widget.FrameLayout.onLayout(FrameLayout.java:261) at com.android.internal.policy.DecorView.onLayout(DecorView.java:726) at android.view.View.layout(View.java:17637) at android.view.ViewGroup.layout(ViewGroup.java:5575) at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2346) at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2068) 06-22 10:11:41.107 22646-22646/com.example.aymen.schoolmanager E/AndroidRuntime: at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1254) at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6337) at android.view.Choreographer$CallbackRecord.run(Choreographer.java:874) at android.view.Choreographer.doCallbacks(Choreographer.java:686) at android.view.Choreographer.doFrame(Choreographer.java:621) at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:860) at android.os.Handler.handleCallback(Handler.java:751) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:154) at android.app.ActivityThread.main(ActivityThread.java:6119) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

line 68 points to:

holder.textViewHead.setText(idd.get(position).getSubject());

line 20 points to:

class Adapter extends RecyclerView.Adapter<Adapter.ViewHolder>

Here's my code:

My database class handler:

public class DBhandler extends SQLiteOpenHelper {
    private static final String databas_name="newdata.db";
    public static final int databas_version=1;
    public static String ID="id";
    int id;
    SQLiteDatabase dj;
    ArrayList<dates> er=new ArrayList<dates>();
    SQLiteDatabase db;
    DBhandler helper;
    String TYPE="type";
    String sub="Subject";
    String Title="Title";
    String det="Detail";
    String TabN="ClassExams";
    int i;

    public DBhandler(Context context)
    {
        super(context,databas_name,null,databas_version);
    }




    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE if not EXISTS ClassExams(id INTEGER primary key,type TEXT,Subject TEXT,Title TEXT,Detail TEXT) ");
    }


    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP table if EXISTS ClassExams");
        onCreate(db);

    }



    public void insert(String type, String sub, String title, String detaill)
    {
        SQLiteDatabase db=this.getWritableDatabase();
        ContentValues contentValues=new ContentValues();
        contentValues.put("type",type);
        contentValues.put("Subject",sub);
        contentValues.put("Title",title);
        contentValues.put("Detail",detaill);
        db.insert("ClassExams",null,contentValues);
        db.close();



     }


    public ArrayList getAs(String Type)
    {


        String DATABASE_TABLE="ClassExams";
        String type="type";
        String quer = "SELECT * FROM " + DATABASE_TABLE + " WHERE " + type + "='" + Type+"'";
        ArrayList arrayList=new ArrayList();
        SQLiteDatabase db=this.getReadableDatabase();

        Cursor res=db.rawQuery(quer,null);
        res.moveToFirst();
        while (res.isAfterLast()==false){
            arrayList.add(res.getString(res.getColumnIndex("id")));

            //  arrayList.add(res.getString(res.getColumnIndex("Subject")));
            // arrayList.add(res.getString(res.getColumnIndex("Title")));
            // arrayList.add(res.getString(res.getColumnIndex("Detail")));
            res.moveToNext();

        }
        return arrayList;

    }


    public void deleteNote(int x){
        String TABLE_NAME="ClassExams";
        String ID="id";
        SQLiteDatabase db = this.getWritableDatabase();
        db.delete(TABLE_NAME, ID + " = ?",new String[] {String.valueOf(x)});
    }





}

My adapter class:

public class Adapter extends RecyclerView.Adapter<Adapter.ViewHolder> {
    Context activity;
    private ArrayList<dates> idd;

    public class ViewHolder extends RecyclerView.ViewHolder {

        public TextView textViewHead;
        public TextView textViewDown;
        public TextView buttonViewOption;
        public int position;
        public ViewHolder(View itemView) {
            super(itemView);

            textViewHead = (TextView) itemView.findViewById(id.text1);

            textViewDown = (TextView) itemView.findViewById(id.text2);

            buttonViewOption = (TextView) itemView.findViewById(R.id.textViewOptions);
        }
    }


    public Adapter (Context context, ArrayList<dates> id) {
      this.activity=context;
         this.idd=id;

    }
    @Override
   public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        LayoutInflater inflater=LayoutInflater.from(activity);
      //  View row=inflater.inflate(layout.costum_row,parent,false);
        View view = LayoutInflater.from(parent.getContext()).inflate(layout.costum_row, null);

        ViewHolder holder=new ViewHolder(view);
        return holder;
    }
    public void onBindViewHolder(final Adapter.ViewHolder holder, final int position) {
        //  dates object=idd.get(position);
        // String firstText = object.getDetail();
        // String secondText = object.getSubject();


        holder.textViewDown.setText("Somthing");
        holder.textViewHead.setText(idd.get(position).getSubject());
        holder.buttonViewOption.setOnClickListener(new View.OnClickListener() {
            public void onClick(View view) {

                PopupMenu popup = new PopupMenu(activity, holder.buttonViewOption);

                popup.inflate(R.menu.option_menu);

                popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
                    @Override
                    public boolean onMenuItemClick(MenuItem item) {

                        switch (item.getItemId()) {
                            case id.Update:

                                break;
                            case R.id.menu2:

                                break;
                            case id.Delete:

                                delete();
//db.deleteNote(Integer.parseInt(j));

                                // db.deleteNote(getid);
                        }
                        return false;
                    }
                });
                //displaying the popup
                popup.show();
            }

            public void delete() {
                idd.remove(position);
                notifyItemRemoved(position);
                notifyItemRangeChanged(position, idd.size());
                holder.itemView.setVisibility(View.GONE);
            }

        });
    }

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

My class:

public class dates {
    String Subject,Title,Detail,type;
     int id;

    public dates(String subject, String title, String detail, String type, int id) {
        this.Subject = subject;
        this.Title = title;
        this.Detail = detail;
        this.type = type;
        this.id = id;
    }

    dates()
    {

    }


    public String getSubject() {
        return Subject;
    }

    public  void setSubject(String subject) {
        Subject= subject;
    }

    public String getTitle() {
        return Title;
    }

    public void setTitle(String title) {
        Title = title;
    }

    public String getDetail() {
        return Detail;
    }

    public void setDetail(String detail) {
        Detail = detail;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public int getId() {
        return id;
    }

    public void seti(int id) {
        this.id = id;
    }
1
androidandroid-recyclerviewadapterclasscastexception
There is no type cast in the line you have shown. Please post the full stack trace. If you identified the line correctly, the error is in one of methods called from this line. – Henry
@Henry holder.textViewHead.setText(idd.get(position).getSubject()); – Aymen ch
This looks very strange. Are you sure the stack trace corresponds to the latest code? Try to completely rebuild and reinstall the App. – Henry
@Henry same problem :/ nothing changed – Aymen ch
please any helppppp – Aymen ch

1 Answers

0
votes

Not all the necessary code is shown here, but I assume the Array list coming from ArrayList DBHandler.getAs() is passed as id parameter to the Adapter constuctor

public Adapter (Context context, ArrayList<dates> id)

There should have been a compiler warning about "unchecked or unsafe operations".

What getAs returns is actually a list containing String objects and this is now interpreted as a list containing dates objects, which results in the class cast exception as soon as one of the elements is accessed.

Two lessons can be learned from this:

  1. Don't ignore compiler warnings
  2. Don't use raw collection classes