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POLogcat error while getting data from Sqlitedatabase to listview
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  1. POLogcat error while getting data from Sqlitedatabase to listview
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    copied!<p>and my XML file is </p> <pre><code> &lt;ListView android:id="@android:id/list" android:layout_width="match_parent" android:layout_height="wrap_content" &gt; &lt;/ListView&gt; &lt;/RelativeLayout&gt; </code></pre> <p>in these database i am getting values from database and displaying them in a listview. my main activity is package com.example.kern;</p> <pre><code> import android.os.Bundle; import android.provider.Contacts.People; import android.app.Activity; import android.app.ListActivity; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.view.Menu; import android.widget.CursorAdapter; import android.widget.ListView; import android.widget.SimpleCursorAdapter; public class Second extends ListActivity { DatabaseAdapter helper; SQLiteDatabase db; private CursorAdapter dataSource; private static final String fields[] = { "Name", "Numb"}; ListView lv; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_second); helper=new DatabaseAdapter(this); helper.open(); lv=(ListView)findViewById(android.R.id.list); Cursor data = db.query("Mycon", fields,null, null, null, null, null); dataSource = new SimpleCursorAdapter(this, R.layout.activity_second, data, fields, new int[] { R.id.name, R.id.number }); lv.setAdapter(dataSource); } } </code></pre> <p>and mydatabase adapter class is package com.example.kern;</p> <pre><code> import android.content.ContentValues; import android.content.Context; import android.database.SQLException; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; import android.util.Log; import com.example.kern.DatabaseAdapter; import com.example.kern.DatabaseAdapter.DatabaseHelper; public class DatabaseAdapter { DatabaseHelper helper; SQLiteDatabase db; static final int VERSION=2; static final String DATA_NAME="Mycontsc"; private static final String query = "create table Mycon(id Integer primary key,Name text,Numb text)"; //the query has been changed private final Context mCtx; public DatabaseAdapter(Context ctx) { this.mCtx = ctx; } //DatabaseHelper has become a subclass public class DatabaseHelper extends SQLiteOpenHelper { public DatabaseHelper(Context context) { super(context, DATA_NAME, null, VERSION); // TODO Auto-generated constructor stub } @Override public void onCreate(SQLiteDatabase arg0) { // TODO Auto-generated method stub arg0.execSQL(query); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { // TODO Auto-generated method stub } } public DatabaseAdapter open() throws SQLException { helper = new DatabaseHelper(mCtx); db=helper.getWritableDatabase(); db=helper.getReadableDatabase(); return this; } public void close() { helper.close(); } public long AddDetail(String name,String num) { ContentValues vals=new ContentValues(); vals.put("Name",name); vals.put("Numb", num); long a=db.insert("Mycon", null, vals); return a; } } </code></pre> <p>it is showing null pointer exception in logcat</p> <pre><code> 09-18 10:32:02.631: E/AndroidRuntime(2286): FATAL EXCEPTION: main 09-18 10:32:02.631: E/AndroidRuntime(2286): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.kern/com.example.kern.Second}: java.lang.NullPointerException 09-18 10:32:02.631: E/AndroidRuntime(2286): Caused by: java.lang.NullPointerException 09-18 10:32:02.631: E/AndroidRuntime(2286): at com.example.kern.Second.onCreate(Second.java:29) </code></pre> <p>please check the program and give me the solution,it is showing exception,alerady there is values in the database and i am retriving them.. </p>
 

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