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POCustom list view in android giving error while updating data from database in android
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copied!<p>I am trying to add check box and some text view (text view is getting value from database) in customized list view but it is giving error of NullPointerException. I don't know why and what is wrong with my code. Below is my code.</p> <p>My MainActivity Class:</p> <pre><code>public class Classes extends Activity { ImageView imageViewNewClass; ListView mListView; String[] stg1; List<String[]> names2 = null; DataManipulatorClass dataManipulator; CustomAdapter customAdapter; public Classes classes = null; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.classes); imageViewNewClass = (ImageView) findViewById(R.id.newclass); mListView = (ListView) findViewById(R.id.displaydata); imageViewNewClass.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { Intent intent = new Intent(Classes.this, Class_Create.class); startActivity(intent); } }); Resources res =getResources(); classes = this; dataManipulator = new DataManipulatorClass(this); names2 = dataManipulator.selectAll(); stg1 = new String[names2.size()]; int x = 0; String stg = null; for (String[] name : names2) { stg = "Class Name : " + name[1]; stg1[x] = stg; x++; } customAdapter= new CustomAdapter( classes, stg1,res ); mListView.setAdapter( customAdapter ); customAdapter.notifyDataSetChanged(); mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() { public void onItemClick(AdapterView<?> parent, View item, int position, long id) { Toast.makeText(getApplicationContext(), "Listview item clicked", Toast.LENGTH_LONG).show(); } }); } } </code></pre> <p>CustomAdapterClass.java</p> <pre><code>public class CustomAdapter extends BaseAdapter { /*********** Declare Used Variables *********/ private Activity activity; private String[] data; private static LayoutInflater inflater = null; public Resources res; int i = 0; String[] stg1; List<String[]> names2 = null; DataManipulatorClass dataManipulator; /************* CustomAdapter Constructor *****************/ public CustomAdapter(Activity a, String[] stg1, Resources resLocal) { /********** Take passed values **********/ activity = a; data = stg1; res = resLocal; /*********** Layout inflator to call external xml layout () ***********/ inflater = (LayoutInflater) activity .getSystemService(Context.LAYOUT_INFLATER_SERVICE); } /******** What is the size of Passed Arraylist Size ************/ public int getCount() { if (data.length <= 0) return 1; return data.length; } public Object getItem(int position) { return position; } public long getItemId(int position) { return position; } public static class ViewHolder { public CheckBox checkBox; public TextView textView; } public View getView(int position, View convertView, ViewGroup parent) { View vi = convertView; ViewHolder holder; if (convertView == null) { vi = inflater.inflate(R.layout.check, null); holder = new ViewHolder(); holder.checkBox = (CheckBox) vi.findViewById(R.id.checkBox1); holder.textView = (TextView) vi.findViewById(R.id.selection); vi.setTag(holder); } else holder = (ViewHolder) vi.getTag(); if (data.length <= 0) { holder.textView.setText("No Data"); } else { dataManipulator = new DataManipulatorClass(this); names2 = dataManipulator.selectAll(); stg1 = new String[names2.size()]; int x = 0; String stg = null; for (String[] name : names2) { stg = "Class Name : " + name[1]; stg1[x] = stg; x++; } holder.textView.setText(stg1[x]); } return vi; } public void onClick(View v) { Log.v("CustomAdapter", "=====Row button clicked====="); } } </code></pre> <p>DataManipulator.Java</p> <pre><code>public class DataManipulatorClass { private static final String DATABASE_NAME = "mydatabaseclass.db"; private static final int DATABASE_VERSION = 1; static final String TABLE_NAME = "newtableclass"; private static Context context; static SQLiteDatabase db; private SQLiteStatement insertStmt; private static final String INSERT = "insert into " + TABLE_NAME + "(classname) values (?)"; public DataManipulatorClass(Context context) { DataManipulatorClass.context = context; OpenHelper openHelper = new OpenHelper(DataManipulatorClass.context); DataManipulatorClass.db = openHelper.getWritableDatabase(); this.insertStmt = DataManipulatorClass.db.compileStatement(INSERT); } public DataManipulatorClass(CustomAdapter customAdapter) { OpenHelper openHelper = new OpenHelper(DataManipulatorClass.context); DataManipulatorClass.db = openHelper.getWritableDatabase(); this.insertStmt = DataManipulatorClass.db.compileStatement(INSERT); } public long insert(String classname) { this.insertStmt.bindString(1, classname); return this.insertStmt.executeInsert(); } public void deleteAll() { db.delete(TABLE_NAME, null, null); } public List<String[]> selectAll() { List<String[]> list = new ArrayList<String[]>(); Cursor cursor = db.query(TABLE_NAME, new String[] { "id", "classname" }, null, null, null, null, "classname asc"); int x = 0; if (cursor.moveToFirst()) { do { String[] b1 = new String[] { cursor.getString(0), cursor.getString(1) }; list.add(b1); x = x + 1; } while (cursor.moveToNext()); } if (cursor != null && !cursor.isClosed()) { cursor.close(); } cursor.close(); return list; } public void delete(int rowId) { db.delete(TABLE_NAME, null, null); } private static class OpenHelper extends SQLiteOpenHelper { OpenHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); } @Override public void onCreate(SQLiteDatabase db) { db.execSQL("CREATE TABLE " + TABLE_NAME + " (id INTEGER PRIMARY KEY, classname TEXT)"); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME); onCreate(db); } } } </code></pre> <p>In Classes Class I have listview in which i want to show the data, My logcat is here <a href="http://i.share.pho.to/9739fdca_o.png" rel="nofollow">http://i.share.pho.to/9739fdca_o.png</a></p> <p>It is giving error on mListView.setAdapter( customAdapter ); this line while setting adapter in listview as a customadapter...</p> <p>Thanks in advance...</p>

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