I have an existing database that I created and I would like to get the data from that to populate a listview in android. For now I would first just like to get my database connected and working and see if I can get the data out of it. My database is called HealthySizing and in it I have a Shirts table with 6 columns. So I have a DBHelper class, a MainActivity.java, and an activity_main.xml, I have posted below these three files and the error that I get, so can someone help me out with this? Does anyone know why I am getting this error and how I can fix it to get some data out of my database?
package com.example.ListViewFromSQLiteDB;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Locale;
public class DBHelper extends SQLiteOpenHelper {
private static final String DATABASE_PATH = "/data/data/com.example.ListViewFromSQLiteDB/databases";
private static final String DATABASE_NAME = "HealthySizing.db";
private static final int SCHEMA_VERSION = 1;
public SQLiteDatabase dbSqlite;
private final Context myContext;
public static String tableName = "Shirts";
public DBHelper(Context context) {
super(context, DATABASE_NAME, null, SCHEMA_VERSION);
this.myContext = context;
}
public void onCreate(SQLiteDatabase db) {
}
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public void createDatabase() {
createDB();
}
private void createDB() {
boolean dbExist = DBExists();
if (!dbExist) {
this.getReadableDatabase();
copyDBFromResource();
}
}
private boolean DBExists() {
SQLiteDatabase db = null;
try {
String databasePath = DATABASE_PATH + DATABASE_NAME;
db = SQLiteDatabase.openDatabase(databasePath, null, SQLiteDatabase.OPEN_READWRITE);
db.setLocale(Locale.getDefault());
db.setLockingEnabled(true);
db.setVersion(1);
} catch (SQLiteException e) {
Log.e("SqlHelper", "database not found");
}
if (db != null) {
db.close();
}
return db != null ? true : false;
}
private void copyDBFromResource() {
InputStream inputStream = null;
OutputStream outStream = null;
String dbFilePath = DATABASE_PATH + DATABASE_NAME;
try {
inputStream = myContext.getAssets().open(DATABASE_NAME);
outStream = new FileOutputStream(dbFilePath);
byte[] buffer = new byte[1024];
int length;
while((length = inputStream.read(buffer)) > 0) {
outStream.write(buffer, 0, length);
}
outStream.flush();
outStream.close();
inputStream.close();
} catch (IOException e) {
throw new Error("Problem copying database from resource file");
}
}
@Override
public synchronized void close() {
if (dbSqlite != null) {
dbSqlite.close();
}
super.close();
}
}
/*public class DBHelper extends SQLiteOpenHelper{
public SQLiteDatabase DB;
public String DBPath;
public static String DBName = "HealthySizing";
public static final int version = '3';
public static Context currentContext;
public static String tableName = "Shirts";
public DBHelper(Context context) {
super(context, DBName, null, version);
currentContext = context;
DBPath = "/data/data/" + context.getPackageName() + "/databases";
createDatabase();
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
}
private void createDatabase() {
boolean dbExists = checkDbExists();
if (dbExists) {
// do nothing
}
}
private boolean checkDbExists() {
SQLiteDatabase checkDB = null;
try {
String myPath = DBPath + DBName;
checkDB = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READONLY);
} catch (SQLiteException e) {
// database doesn't exist yet.
}
if (checkDB != null) {
checkDB.close();
}
return checkDB != null ? true : false;
}
}
*/package com.example.ListViewFromSQLiteDB;
import java.util.ArrayList;
import android.app.ListActivity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.os.Bundle;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.TextView;
public class MainActivity extends ListActivity {
private ArrayList<String> results = new ArrayList<String>();
private String tableName = DBHelper.tableName;
private SQLiteDatabase newDB;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
openAndQueryDatabase();
displayResultList();
}
private void displayResultList() {
TextView tView = new TextView(this);
//tView.setText("This data is retrieved from the database and only 4 " +
// "of the results are displayed");
getListView().addHeaderView(tView);
setListAdapter(new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, results));
getListView().setTextFilterEnabled(true);
}
private void openAndQueryDatabase() {
try {
DBHelper dbHelper = new DBHelper(this.getApplicationContext());
newDB = dbHelper.getWritableDatabase();
Cursor c = newDB.rawQuery("SELECT Brand FROM " +
tableName, null);
if (c != null ) {
if (c.moveToFirst()) {
do {
String brand = c.getString(c.getColumnIndex("Brand"));
results.add(brand);
}while (c.moveToNext());
}
}
} catch (SQLiteException se ) {
Log.e(getClass().getSimpleName(), "Could not create or Open the database");
} finally {
if (newDB != null)
newDB.execSQL("DELETE FROM " + tableName);
newDB.close();
}
}
}04-11 15:41:48.558 1923-1923/com.example.ListViewFromSQLiteDB I/art﹕ Not late-enabling -Xcheck:jni (already on)
04-11 15:41:51.974 1923-1923/com.example.ListViewFromSQLiteDB E/MainActivity﹕ Could not create or Open the database
04-11 15:41:51.975 1923-1923/com.example.ListViewFromSQLiteDB D/AndroidRuntime﹕ Shutting down VM
--------- beginning of crash
04-11 15:41:51.975 1923-1923/com.example.ListViewFromSQLiteDB E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.ListViewFromSQLiteDB, PID: 1923
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ListViewFromSQLiteDB/com.example.ListViewFromSQLiteDB.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.database.sqlite.SQLiteDatabase.close()' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.database.sqlite.SQLiteDatabase.close()' on a null object reference
at com.example.ListViewFromSQLiteDB.MainActivity.openAndQueryDatabase(MainActivity.java:59)
at com.example.ListViewFromSQLiteDB.MainActivity.onCreate(MainActivity.java:22)
at android.app.Activity.performCreate(Activity.java:5933)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
device not found<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.ListViewFromSQLiteDB"
android:versionCode="1"
android:versionName="1.0">
<application android:icon="@drawable/ic_launcher" android:label="@string/app_name">
<activity android:name="com.example.ListViewFromSQLiteDB.MainActivity"
android:label="@string/app_name">
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest><?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:weightSum="1">
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
android:layout_weight="0.12" />
</LinearLayout>
