App is crash when I show data of DB in ListView

Question

My app crashes when I want to show sone data in my listview.

package com.example.sqliteapplication;


import java.util.ArrayList;
import java.util.List;

import android.R.string;
import android.app.Activity;
import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.ListView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.Toast;

public class SmsMerge extends Activity  {
    private ImageButton btn;
    private ImageButton imgb;
    private TemplateOperation templateDBoperation;
    ArrayList<User> arr;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_sms_merge);
        templateDBoperation = new TemplateOperation(this);
        templateDBoperation.open();
        List<String> values=new ArrayList<String>();
         values = templateDBoperation.getAllTemplate();
         Object[] obj=values.toArray();

         arr=new ArrayList<User>();
         String[] da=new String[obj.length];
         for(int i=0; i<obj.length; i++)
        {
             da[i]=(String)obj[i];
             arr.add(new User(da[i]));
        }


        Toast.makeText(getBaseContext(), "Siddiqueeeeeeeeeeeeeeeeeee"+obj.length, Toast.LENGTH_SHORT).show();
        ListView listview = (ListView)findViewById(android.R.id.list);
MyListAdapter adpttt=new MyListAdapter(SmsMerge.this,R.layout.row,arr);

listview.setItemsCanFocus(false);
        listview.setAdapter(adpttt);
        imgb=(ImageButton)findViewById(R.id.btnaddtemplate);
        imgb.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                Intent intent = new Intent(SmsMerge.this, SqliteActivity.class);
                startActivity(intent);
            }   
        });


}

my custom adapter code is here....

package com.example.sqliteapplication;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.MenuInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.TextView;
import android.widget.Toast;

public class MyListAdapter extends ArrayAdapter<User> {

    int inflatr;
    Context ctxt;
    ArrayList<User> data=new ArrayList<User>();
    public MyListAdapter(Context context, int layoutResourceId,
            ArrayList<User> data) {
        super(context, layoutResourceId, data);
        this.inflatr = layoutResourceId;
        this.ctxt = context;
        this.data= data;
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        UserHolder holder = null;
         View row = convertView;
        if(convertView==null)
        {
             LayoutInflater inflater = ((Activity) ctxt).getLayoutInflater();
              row = inflater.inflate(inflatr, parent, false);
             holder = new UserHolder();
             holder.textName=(TextView)row.findViewById(R.id.label);
             holder.btnEdit = (ImageButton) row.findViewById(R.id.atomPay_removePay);
             row.setTag(holder);
        }
        else
        {
             holder = (UserHolder) row.getTag();            
        }


        User dta=data.get(position);

            holder.textName.setText(dta.getName());
        holder.btnEdit.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
            }
        });
        return row;
    }
    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return data.size();
    }

}

my Template Class is here...

package com.example.sqliteapplication;

public class Template {
        private int id;
        private String name;
        private String Description;
        public long getId() {
            return id;
        }
        public void setId(int id) {
            this.id = id;
        }
        public String getName() {
            return this.name;
        }
        public void setName(String name) {
            this.name = name;
        }

        public void setDescription(String Description) {
            this.Description = Description;
        }
        public String getDescription()
        {
            return Description;
        }
        @Override
        public String toString() {
            return name;
        }
    }

MY Database wraper code is here.....

package com.example.sqliteapplication;

import android.content.Context;
import android.database.DatabaseErrorHandler;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;

public class DataBaseWraper extends SQLiteOpenHelper {
    public static final String TEMPLATE = "template";
    public static final String TEMPLATE_ID = "_id";
    public static final String PERSON_NAME = "_name";
    public static final String TEMPLATE_DESCRIPTION = "_description";
    public static final String DATABASE_NAME = "Template.db";
    public static final int DATABASE_VERSION = 1;
    private static final String DATABASE_CREATE_Trmplate = "create table "
            + TEMPLATE + "(" + TEMPLATE_ID
            + " integer primary key autoincrement, " + PERSON_NAME
            + " text not null, "+ TEMPLATE_DESCRIPTION
            + " text not null);";

    public DataBaseWraper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(DATABASE_CREATE_Trmplate);

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // you should do some logging in here
        // ..

        db.execSQL("DROP TABLE IF EXISTS " + TEMPLATE);
        onCreate(db);
    }

}

My Template Operetion code is here

package com.example.sqliteapplication;

import java.util.ArrayList;
import java.util.List;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;

public class TemplateOperation {
    // Database fields
    private DataBaseWraper dbHelper;
    private String[] TEMPLATE_TABLE_COLUMNS = { DataBaseWraper.TEMPLATE_ID,
            DataBaseWraper.PERSON_NAME, DataBaseWraper.TEMPLATE_DESCRIPTION };
    private SQLiteDatabase database;

    public TemplateOperation(Context context) {
        dbHelper = new DataBaseWraper(context);
    }

    public void open() throws SQLException {
        database = dbHelper.getWritableDatabase();
    }

    public void close() {
        dbHelper.close();
    }

    public Template addTemplate(String Description, String Person_Name) {

        ContentValues values = new ContentValues();
        values.put(DataBaseWraper.PERSON_NAME, Person_Name);
        values.put(DataBaseWraper.TEMPLATE_DESCRIPTION, Description);

        long templateId = database.insert(DataBaseWraper.TEMPLATE, null, values);

        // now that the student is created return it ...
        Cursor cursor = database.query(DataBaseWraper.TEMPLATE,
                TEMPLATE_TABLE_COLUMNS, DataBaseWraper.TEMPLATE_ID + " = "
                        + templateId, null, null, null, null);

        cursor.moveToFirst();

        Template newComment = parseTemplate(cursor);
        cursor.close();
        return newComment;
    }

    public void deleteStudent(Template comment) {
        long id = comment.getId();
        System.out.println("Comment deleted with id: " + id);
        database.delete(DataBaseWraper.TEMPLATE, DataBaseWraper.TEMPLATE_ID
                + " = " + id, null);
    }

    public List getAllTemplate() {
        List students = new ArrayList();
        Cursor cursor = database.query(DataBaseWraper.TEMPLATE,
                TEMPLATE_TABLE_COLUMNS, null, null, null, null,
                null);

        cursor.moveToFirst();
        while (!cursor.isAfterLast()) {
            Template student = parseTemplate(cursor);
            students.add(student);
            cursor.moveToNext();
        }
        cursor.close();
        Log.d(""+students, "humayoonnnnn");
        return students;
    }

    private Template parseTemplate(Cursor cursor) {
        Template template = new Template();
        template.setId((cursor.getInt(0)));
        template.setName(cursor.getString(1));
        return template;
    }

}

The stacktrace for the error:

05-08 18:44:03.336: E/AndroidRuntime(10100): FATAL EXCEPTION: main
05-08 18:44:03.336: E/AndroidRuntime(10100): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.sqliteapplication/com.example.sqliteapplication.SmsMerge}: java.lang.ClassCastException: com.example.sqliteapplication.Template cannot be cast to java.lang.String
05-08 18:44:03.336: E/AndroidRuntime(10100):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2306)
05-08 18:44:03.336: E/AndroidRuntime(10100):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2358)
05-08 18:44:03.336: E/AndroidRuntime(10100):    at android.app.ActivityThread.access$600(ActivityThread.java:156)
05-08 18:44:03.336: E/AndroidRuntime(10100):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1340)
05-08 18:44:03.336: E/AndroidRuntime(10100):    at android.os.Handler.dispatchMessage(Handler.java:99)
05-08 18:44:03.336: E/AndroidRuntime(10100):    at android.os.Looper.loop(Looper.java:153)
05-08 18:44:03.336: E/AndroidRuntime(10100):    at android.app.ActivityThread.main(ActivityThread.java:5299)
05-08 18:44:03.336: E/AndroidRuntime(10100):    at java.lang.reflect.Method.invokeNative(Native Method)
05-08 18:44:03.336: E/AndroidRuntime(10100):    at java.lang.reflect.Method.invoke(Method.java:511)
05-08 18:44:03.336: E/AndroidRuntime(10100):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
05-08 18:44:03.336: E/AndroidRuntime(10100):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
05-08 18:44:03.336: E/AndroidRuntime(10100):    at dalvik.system.NativeStart.main(Native Method)
05-08 18:44:03.336: E/AndroidRuntime(10100): Caused by: java.lang.ClassCastException: com.example.sqliteapplication.Template cannot be cast to java.lang.String
05-08 18:44:03.336: E/AndroidRuntime(10100):    at com.example.sqliteapplication.SmsMerge.onCreate(SmsMerge.java:43)
05-08 18:44:03.336: E/AndroidRuntime(10100):    at android.app.Activity.performCreate(Activity.java:5122)
05-08 18:44:03.336: E/AndroidRuntime(10100):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1081)
05-08 18:44:03.336: E/AndroidRuntime(10100):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2270)
05-08 18:44:03.336: E/AndroidRuntime(10100):    ... 11 more

Answer 1

I guess da[i]=(String)obj[i]; is what it all comes down to.

The error already states:

Caused by: java.lang.ClassCastException: com.example.sqliteapplication.Template cannot be cast to java.lang.String

In other words: You cant cast your Template-Object to String.

edit An alterantive would be using obj[i].toString(). In this case you could overwrite the toString()-Method for each class stored in the Object-Array, so that the returned output makes sense.