Develop Reference

I'm getting every Time Random repeating Data in Sqlite Android I want Random data without repeating

I'm getting many time repeating data from Sqlite / Android database. I want to get recode without repeating in Android cursor.
Here's my query:
public Cursor getQuizQuiestion(String cat, String level, String questionNo) {
String QUERY_SELECT_QUIESTION = "SELECT * FROM " +TABLE_QUIESTION +" WHERE "+COL_CAT+ " = '" +cat+"' AND "
+COL_LEVEL+ " = " +level+" ORDER BY RANDOM() LIMIT 1";
Cursor cursor = db.rawQuery(QUERY_SELECT_QUIESTION, null);
return cursor;
}

I Have Simple Example if I Used In My Project I think MayBe IT's Help You;
public ArrayList<ModelRandomList> getRandomData(String city){
ArrayList<ModelRandomList> modelRandomListArrayListLists = new ArrayList<ModelRandomList>();
String queryRandomData ="SELECT DISTINCT * FROM "+TABLE_NAME+" WHERE "+COL_CITY + "=?"+ "Order BY RANDOM()";
Cursor cursor = db.rawQuery(queryRandomData,new String[] { String.valueOf(city) });
if(cursor.getCount() != 0){
while (cursor.moveToNext()){
/*mName =cursor.getString(0);
mCity = cursor.getString(1);
Log.d(TAG,mName +" City "+mCity );*/
ModelRandomList modelRandomList = new ModelRandomList();
modelRandomList.setUserName(cursor.getString(0));
modelRandomList.setUserCity(cursor.getString(1));
modelRandomListArrayListLists.add(modelRandomList);
}
Random random = new Random();
Collections.shuffle(modelRandomListArrayListLists,random);
}
Log.d(TAG, "Get Random Totla No of Recode Found "+cursor.getCount());
return modelRandomListArrayListLists;
}
and in Your Activity
public class MainActivity extends AppCompatActivity {
private static final String TAG = MainActivity.class.getSimpleName();
private SqlLiteDataBaseHelper sqlLiteDataBaseHelper;
private Button btGetRandomData;
private ArrayList<ModelRandomList> modelRandomLists;
private Button btSingleRandomData;
private int position = 0;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
modelRandomLists = new ArrayList<ModelRandomList>();
sqlLiteDataBaseHelper = new SqlLiteDataBaseHelper(MainActivity.this);
try{
if(sqlLiteDataBaseHelper.checkDataBase()){
Log.e(TAG, "Data Base Already Exists");
}else {
sqlLiteDataBaseHelper.CopyDataBaseFromAsset();
}
sqlLiteDataBaseHelper.openDataBase();
try {
Log.e(TAG, "No Of Racode In DataBase " + sqlLiteDataBaseHelper.getDataCount());
}catch (Exception e){
e.printStackTrace();
}
}catch (Exception e){
e.printStackTrace();
}
init();
}
private void init() {
btGetRandomData = (Button)findViewById(R.id.btRandomData);
btSingleRandomData = (Button)findViewById(R.id.btSingleRandomData);
}
#Override
protected void onResume() {
super.onResume();
btGetRandomData.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
modelRandomLists = sqlLiteDataBaseHelper.getRandomData("A");
for (ModelRandomList crt : modelRandomLists) {
Log.e(TAG, " " + crt.getUserName());
Log.e(TAG, " " + crt.getUserCity());
}
}
});
btSingleRandomData.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
try{
Log.d(TAG,modelRandomLists.get(position).getUserName());
position ++;
}catch (Exception e){
e.printStackTrace();
position =0;
}
}
});
}
}

You would have to keep a track of what questions have been seen before. What about this:
private List<Integer> seenQuestions = new ArrayList<>();
public Cursor getUseenQuizQuestion(String cat,String level,String questionNo) {
Cursor cursor = getQuizQuiestion(cat, level, questionNo);
while(cursor == null) { // This could be an infinite loop!!
cursor = getQuizQuiestion(cat, level, questionNo);
}
return cursor;
}
private Cursor getQuizQuiestion(String cat,String level,String questionNo){
String QUERY_SELECT_QUIESTION = "SELECT * FROM " +TABLE_QUIESTION +" WHERE "+COL_CAT+ " = '" +cat+"' AND "
+COL_LEVEL+ " = " +level+" ORDER BY RANDOM() LIMIT 1";
Cursor cursor = db.rawQuery(QUERY_SELECT_QUIESTION, null);
if(cursor.moveToFirst()) {
int resultId = cursor.getString(cursor.getColumnIndexOrThrow("_id"));
if(seenQuestions.contains(resultId)) {
cursor.close();
return null;
}
seenQuestions.add(resultId);
}
return cursor;
}
^ the code sample above has many flaws and could loop infinitely.
But the point is you need to keep track of what has been returned and query again if you have seen it.
Alternatively, you could allow your DB query to return all data and then use a Random value to select one of the items.

There is no way to create unique results if you are querying over and over again.
Since you are not using the questionNo parameter and return a cursor anyway: why not just remove the limit 1 and add the distinct clause to your statement?
If you do it that way, you can use your cursor to iterate over the unique questions:
String QUERY_SELECT_QUIESTION = "SELECT DISTINCT * FROM " +TABLE_QUIESTION +" WHERE "+COL_CAT+ " = '" +cat+"' AND "
+COL_LEVEL+ " = " +level+" ORDER BY RANDOM()";
Then you can iterate over the questions until you have none or whatever your conditions are:
Cursor cursor = db.rawQuery(QUERY_SELECT_QUIESTION, null);
try {
while (cursor.moveToNext()) {
//display question or copy them to a member or whatever
}
} finally {
cursor.close();
}

Find and interate all SMS/MMS messages in android

First and foremost, I found this answer particularly helpful. However, it made me wonder how one goes about finding such information.
I can't seem to figure out how to iterate all the messages in my inbox. My current solution uses Uri.parse("content://mms-sms/conversations") in which I give use "_id" and "ct_t". However, it seems I only find the three conversations in my phone despite having 30 msges (20 of them in the save conversation thread and the others divided between two other conversations). Would make sense for such a statement content://mms-sms/conversations. However, the other providers seem to deal only with SMS OR MMS. Isn't there a way to just iterate the entire list of messages in this fashion where I replace "content://mms-sms/conversations" with something else?
public boolean refresh() {
final String[] proj = new String[]{"_id","ct_t"};
cursor = cr.query(Uri.parse("content://mms-sms/conversations"),proj,null,null,null);
if(!(cursor.moveToFirst())) {
empty = true;
cursor.close();
return false;
}
return true;
}
I iterate the messages with a next function
public boolean next() {
if(empty) {
cursor.close();
return false;
}
msgCnt = msgCnt + 1;
Msg msg;
String msgData = cursor.getString(cursor.getColumnIndex("ct_t"));
if("application/cnd.wap.multipart.related".equals(msgData)) {
msg = ParseMMS(cursor.getString(cursor.getColumnIndex("_id")));
} else {
msg = ParseSMS(cursor.getString(cursor.getColumnIndex("_id")));
}
if(!(cursor.moveToNext())) {
empty = true;
cursor.close();
return false;
}
return true;
}

Well, what I am asking doesn't really seem possible.
For those just starting out on such tasks, it's advisable to learn about how content providers work in general. Each Uri value added to the query returns access to specific tables.
Spending some time looking at the different Telephony.Mmssms tables that one can access and it seems, from my testing, that the only table you can access is using "content://mms-sms/conversations as using "content://mms-sms" leads to a null cursor.
Such is life, and it doesn't really make sense to iterate the messages that way since the content and method of extracting the data differ greatly based on whether or not the msg is an SMS or MMS message. It makes sense to iterate and parse SMS and MMS messages separately and store the interesting data into the same class object type for one to manipulate how they would like at a later date.
Useful to such a topic would be the Telephony.Sms documentation. Which is where one can find a descriptions of the column index fields. You can find the same information for Telephony.Mms as well as the sub table Telephony.Mms.Part, with links to each of the base columns to describe the information.
With this being said, here is a solution to the question How can I iterate all the SMS/MMS messages in the phone? and here is the solution that worked for me.
public class Main extends AppCompatActivity {
//Not shown, Overrides, button to call IterateAll();
//implementations to follow
IterateAll();
public void ScanMMS();
public void ScanSMS();
public void ParseMMS(Msg msg);
public Bitmap getMmsImg(String id);
public String getMmsAddr(String id);
}
IterateAll() just calls the two different functions
IterateAll() {
ScanMMS();
ScanSMS();
}
ScanMMS() will iterate through the content://mms table extracting the data from each MMS.
public void ScanMMS() {
System.out.println("==============================ScanMMS()==============================");
//Initialize Box
Uri uri = Uri.parse("content://mms");
String[] proj = {"*"};
ContentResolver cr = getContentResolver();
Cursor c = cr.query(uri, proj, null, null, null);
if(c.moveToFirst()) {
do {
/*String[] col = c.getColumnNames();
String str = "";
for(int i = 0; i < col.length; i++) {
str = str + col[i] + ": " + c.getString(i) + ", ";
}
System.out.println(str);*/
//System.out.println("--------------------MMS------------------");
Msg msg = new Msg(c.getString(c.getColumnIndex("_id")));
msg.setThread(c.getString(c.getColumnIndex("thread_id")));
msg.setDate(c.getString(c.getColumnIndex("date")));
msg.setAddr(getMmsAddr(msg.getID()));
ParseMMS(msg);
//System.out.println(msg);
} while (c.moveToNext());
}
c.close();
}
}
As one can see, a lot of the important MMS data is in this table, such as the date of the message, the message id and the thread id. You need to use that message ID to pull more information from MMS.
The MMS message is divided into smaller parts of data. Each part contains something different, like an image, or a text portion. You have to iterate each part as I do below.
public void ParseMMS(Msg msg) {
Uri uri = Uri.parse("content://mms/part");
String mmsId = "mid = " + msg.getID();
Cursor c = getContentResolver().query(uri, null, mmsId, null, null);
while(c.moveToNext()) {
/* String[] col = c.getColumnNames();
String str = "";
for(int i = 0; i < col.length; i++) {
str = str + col[i] + ": " + c.getString(i) + ", ";
}
System.out.println(str);*/
String pid = c.getString(c.getColumnIndex("_id"));
String type = c.getString(c.getColumnIndex("ct"));
if ("text/plain".equals(type)) {
msg.setBody(msg.getBody() + c.getString(c.getColumnIndex("text")));
} else if (type.contains("image")) {
msg.setImg(getMmsImg(pid));
}
}
c.close();
return;
}
Each part as the mid field which corresponds to the id of the message found earlier. We search the MMS part library only for that mms id and then iterate the different parts found. ct or content_type as described in the documentation described what the part is, i.e. text, image, etc. I scan the type to see what to do with that part. If it's plain text, I add that text to the current message body (apparently there can be multiple text parts, but I haven't seen it, but I believe it) and if it's an image, than load the image into a bitmap. I imagine Bitmaps will be easy to send with java to my computer, but who knows, maybe want to just load it as a byte array.
Anyway, here is how one will get the image data from the MMS part.
public Bitmap getMmsImg(String id) {
Uri uri = Uri.parse("content://mms/part/" + id);
InputStream in = null;
Bitmap bitmap = null;
try {
in = getContentResolver().openInputStream(uri);
bitmap = BitmapFactory.decodeStream(in);
if(in != null)
in.close();
} catch (IOException e) {
e.printStackTrace();
}
return bitmap;
}
You know, I'm not entirely sure how opening an input stream on the content resolver really works and how it is giving me just the image and not like all the other data, no clue, but it seems to work. I stole this one from some different sources while looking for solutions.
The MMS addresses aren't as straight forward to pull as they are for SMS, but here is how you can get them all. The only thing I haven't been able to do is figure out who the sender was. I'd love it if someone knew that.
public String getMmsAddr(String id) {
String sel = new String("msg_id=" + id);
String uriString = MessageFormat.format("content://mms/{0}/addr", id);
Uri uri = Uri.parse(uriString);
Cursor c = getContentResolver().query(uri, null, sel, null, null);
String name = "";
while (c.moveToNext()) {
/* String[] col = c.getColumnNames();
String str = "";
for(int i = 0; i < col.length; i++) {
str = str + col[i] + ": " + c.getString(i) + ", ";
}
System.out.println(str);*/
String t = c.getString(c.getColumnIndex("address"));
if(!(t.contains("insert")))
name = name + t + " ";
}
c.close();
return name;
}
This was all just for MMS. The good news is that SMS is much simpler.
public void ScanSMS() {
System.out.println("==============================ScanSMS()==============================");
//Initialize Box
Uri uri = Uri.parse("content://sms");
String[] proj = {"*"};
ContentResolver cr = getContentResolver();
Cursor c = cr.query(uri,proj,null,null,null);
if(c.moveToFirst()) {
do {
String[] col = c.getColumnNames();
String str = "";
for(int i = 0; i < col.length; i++) {
str = str + col[i] + ": " + c.getString(i) + ", ";
}
//System.out.println(str);
System.out.println("--------------------SMS------------------");
Msg msg = new Msg(c.getString(c.getColumnIndex("_id")));
msg.setDate(c.getString(c.getColumnIndex("date")));
msg.setAddr(c.getString(c.getColumnIndex("Address")));
msg.setBody(c.getString(c.getColumnIndex("body")));
msg.setDirection(c.getString(c.getColumnIndex("type")));
msg.setContact(c.getString(c.getColumnIndex("person")));
System.out.println(msg);
} while (c.moveToNext());
}
c.close();
}
Here is my simple message structure so anyone may compile the above code quickly if wanted.
import android.graphics.Bitmap;
/**
* Created by rbenedict on 3/16/2016.
*/
//import java.util.Date;
public class Msg {
private String id;
private String t_id;
private String date;
private String dispDate;
private String addr;
private String contact;
private String direction;
private String body;
private Bitmap img;
private boolean bData;
//Date vdat;
public Msg(String ID) {
id = ID;
body = "";
}
public void setDate(String d) {
date = d;
dispDate = msToDate(date);
}
public void setThread(String d) { t_id = d; }
public void setAddr(String a) {
addr = a;
}
public void setContact(String c) {
if (c==null) {
contact = "Unknown";
} else {
contact = c;
}
}
public void setDirection(String d) {
if ("1".equals(d))
direction = "FROM: ";
else
direction = "TO: ";
}
public void setBody(String b) {
body = b;
}
public void setImg(Bitmap bm) {
img = bm;
if (bm != null)
bData = true;
else
bData = false;
}
public String getDate() {
return date;
}
public String getDispDate() {
return dispDate;
}
public String getThread() { return t_id; }
public String getID() { return id; }
public String getBody() { return body; }
public Bitmap getImg() { return img; }
public boolean hasData() { return bData; }
public String toString() {
String s = id + ". " + dispDate + " - " + direction + " " + contact + " " + addr + ": " + body;
if (bData)
s = s + "\nData: " + img;
return s;
}
public String msToDate(String mss) {
long time = Long.parseLong(mss,10);
long sec = ( time / 1000 ) % 60;
time = time / 60000;
long min = time % 60;
time = time / 60;
long hour = time % 24 - 5;
time = time / 24;
long day = time % 365;
time = time / 365;
long yr = time + 1970;
day = day - ( time / 4 );
long mo = getMonth(day);
day = getDay(day);
mss = String.valueOf(yr) + "/" + String.valueOf(mo) + "/" + String.valueOf(day) + " " + String.valueOf(hour) + ":" + String.valueOf(min) + ":" + String.valueOf(sec);
return mss;
}
public long getMonth(long day) {
long[] calendar = {31,28,31,30,31,30,31,31,30,31,30,31};
for(int i = 0; i < 12; i++) {
if(day < calendar[i]) {
return i + 1;
} else {
day = day - calendar[i];
}
}
return 1;
}
public long getDay(long day) {
long[] calendar = {31,28,31,30,31,30,31,31,30,31,30,31};
for(int i = 0; i < 12; i++) {
if(day < calendar[i]) {
return day;
} else {
day = day - calendar[i];
}
}
return day;
}
}
Some final comments and notes on this solution.
The person field seems to always be NULL and later I plan to implement a contact look up. I also haven't been able to identify who sent the MMS message.
I am not super familiar with java and I am still learning it. I am positive there is a data container (ArrayList) (Vector?) that could hold a user defined object. And if sortable by a specific field in the object (date), one could iterate that list and have a chronological order of all the message: both MMS/SMS and both sent/received.

Isn't there a way to just iterate the entire list of messages in this fashion where I replace "content://mms-sms/conversations" with something else?
It is possible to get all MMS and SMS messages in a single query using the content://mms-sms/complete-conversations URL. For some odd reason, there is no Uri field for this in the Telephony.MmsSms class, but it's been available since at least Froyo.
Using this single query will certainly be more efficient than querying the tables separately, and any sorting, grouping, or filtering that needs to be done will definitely be faster performed by the SQLite engine than by manipulating Java collections.
Please note that you must use a specific projection for this query. You cannot pass null or the * wildcard. Furthermore, it would be advisable to include MmsSms.TYPE_DISCRIMINATOR_COLUMN ("transport_type") in your projection - which will have a value of either "mms" or "sms" - to easily distinguish the message type.
The selection, selectionArgs, and orderBy arguments work as usual, and null can be passed for any or all of them.

SQLite: no such table: while compiling

I've got a long running task that I run onResume on my activity. The task involves querying a database then decrypting some data, then manually sorting it then updating the sort order in the database using a transaction.
This works fine when I run it from the Activities main UI thread, but when I execute the same task from within an AsyncTask I always get these errors:
I/SqliteDatabaseCpp(5166): sqlite returned: error code = 1, msg = no such table: Household, db=/mnt/sdcard/myDatabase.db
no such table: while compiling: no such table: Household: , while compiling: SELECT DISTINCT street FROM Household WHERE street IS NOT NULL AND LENGTH(LTRIM(RTRIM(street)))>0
I know that the database exists and that SQL statement is fine because it runs fine outside the AsyncTask. Is there something about access my database from within an AsyncTask that causes problems?
I'm getting errors on the "SELECT DISTINCT" raw query below.
private boolean update_street_sort_order() {
boolean returnValue = false;
DBUtilities objDbUtil = null;
Cursor cCases = null;
final String SORT_ATTRIBUTE = "street_sort_order";
final int STREET_INDEX = 0;
final int ENCRYPTED_STREET = 0;
final int DECRYPTED_STREET = 1;
try {
objDbUtil = DBUtilities.getInstance(this);
if (objDbUtil != null) { // Get list of cases
ArrayList<String[]> alStreet = new ArrayList<String[]>();
SQLiteDatabase sqlitedatabase = objDbUtil.getDatabase();
if (sqlitedatabase != null && sqlitedatabase.isOpen()) {
cCases = sqlitedatabase.rawQuery("SELECT DISTINCT street "
+ "FROM Household " + "WHERE street IS NOT NULL "
+ "AND LENGTH(LTRIM(RTRIM(street)))>0", null);
String _password = this.context.getPassword();
if (cCases != null && cCases.moveToFirst()) {
do { // Create list of en/decrypted streets
alStreet.add(new String[] {
cCases.getString(STREET_INDEX),
Crypto.decrypt(_password,
cCases.getString(STREET_INDEX)) });
} while (cCases.moveToNext());
}
if (cCases != null) {
cCases.close();
cCases = null;
}
int alStreet_length = alStreet.size();
if (alStreet_length > 0) {
Collections.sort(alStreet, new Comparator<String[]>() {
#Override
public int compare(String[] lhs, String[] rhs) {
return lhs[DECRYPTED_STREET]
.compareToIgnoreCase(rhs[DECRYPTED_STREET]);
}
}); // sort decrypted street using custom comparator
StringBuilder sql_transaction = new StringBuilder(
"BEGIN TRANSACTION;" + "UPDATE Household SET "
+ SORT_ATTRIBUTE + "=NULL;");
for (int i = 0; i < alStreet_length; i++) {
sql_transaction.append(String.format(
"UPDATE Household " + "SET "
+ SORT_ATTRIBUTE + "=%1$d "
+ "WHERE street=\"%2$s\";", i,
alStreet.get(i)[ENCRYPTED_STREET]));
}
sql_transaction.append("COMMIT;");
// execute transaction
sqlitedatabase.execSQL(sql_transaction.toString());
}
returnValue = true;
}
}
} catch (Exception e) {
Log.e(Utilities.getFullMethodName(e), e.getMessage());
} finally {
if (objDbUtil != null) { // release resources
objDbUtil.close();
objDbUtil = null;
}
}
return returnValue;

"Null" appended to database input values from a delimited string

I wonder if someone could show me the error of my ways--I've been struggling with this issue for two days, and realize it must be a fundamental error of initializing variables, but...that reflects the level of my java knowledge.
I'm getting a database result on a delimited string wherein each of the segments has "null" appended to it. It seems that no matter how I change the initialization...well, two days!
I'm declaring the following in the class heading area:
private String strListContent;
private SQLiteDatabase database;
private DatabaseHelper helper2 = new DatabaseHelper(this);
private static final String fields[] = { "_id", "listTitle", "listType",
"listContent", "dateCreated", "dateModified" };
private ArrayList<String> textArray = new ArrayList<String>();
private ArrayList<Integer> imageArray = new ArrayList<Integer>();
Then concatenating my items in
final ImageButton addItem = (ImageButton) findViewById(R.id.btnToAddItem);
addItem.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
itemEdit = (EditText) findViewById(R.id.editTextItem);
if (itemEdit.getText().toString().equals("")) {
showToastMessage("Please enter an item to add...");
} else {
String newListItem = itemEdit.getText().toString();
strListContent += newListItem + "|~|";
...
}}}
I'm using the following bare-bones SQLiteOpenHelper:
public class DatabaseHelper extends SQLiteOpenHelper {
public static final String KEY_ID = "_id";
public DatabaseHelper(Context context) {
super(context, "Cursor", null, 1);
}
#Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE IF NOT EXISTS list_data ("
+ KEY_ID
+ " INTEGER PRIMARY KEY AUTOINCREMENT, listTitle TEXT, listType TEXT, listContent TEXT, dateCreated TEXT, dateModified TEXT)");
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// Steps to upgrade the database for the new version ...
}
}
To insert the values as so:
ImageButton saveAndBack = (ImageButton) findViewById(R.id.btnSaveBack);
saveAndBack.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
String title = null;
String listContent = null;
Calendar javaCalendar = null;
title = titleEdit.getText().toString();
title = (title=="" || title==null)?"Untitled List":title;
strListContent = (strListContent=="" || strListContent==null)?"No Items|~|":strListContent;
listContent = strListContent;
String type = "R"; //"Regular List"
javaCalendar = Calendar.getInstance();
String currentDate = javaCalendar.get(Calendar.MONTH) + "/" + (javaCalendar.get(Calendar.DATE) + 1) + "/" + javaCalendar.get(Calendar.YEAR);
database = helper2.getWritableDatabase();
ContentValues values = new ContentValues();
values.put("listTitle", title);
values.put("listType", type);
values.put("listContent", listContent);
values.put("dateCreated", currentDate);
values.put("dateModified", currentDate);
database.insert("list_data", null, values);
Intent i = new Intent(RegularList.this, ActivityMain.class);
startActivity(i);
}
});
}
//
//End of OnCreate(){}
//
Then, when I retrieve from another activity:
DatabaseHelper helper = new DatabaseHelper(this);
database = helper.getWritableDatabase();
Cursor data = database.query("list_data", fields, null, null, null,
null, null);
Integer tindex = data.getColumnIndex("listTitle");
Integer iindex = data.getColumnIndex("listType");
Integer cindex = data.getColumnIndex("listContent");
itemCount = 0;
for (data.moveToFirst(); !data.isAfterLast(); data.moveToNext()) {
showToastMessage(data.getString(cindex));
titleArrayList.add(data.getString(tindex));
if (data.getString(iindex) == "R") {
imageArrayList.add(R.drawable.listview_regular);
} else if (data.getString(iindex) == "L") {
imageArrayList.add(R.drawable.listview_location);
} else {
imageArrayList.add(R.drawable.listview_regular);
}
itemCount++;
}
data.close();
...
I can see in the toast message that each item from the delimited string has "null" appended to the front of it...the other values are fine. I hope this hasn't been too verbose, but...any recommendations? Thanks!

To me it looks like you may have simply not initialised the String strListContent before you first append to it with:
strListContent += newListItem + "|~|";
When you do that, you'll get a "null" prefixed in front of the value you are trying to append, just as you observe.
Perhaps you can just initialise in the declaration:
private String strListContent = "";

How to save/retrieve words to/from SQlite database?

Sorry if I repeat my question but I have still had no clues of what to do and how to deal with the question.
My app is a dictionary. I assume that users will need to add words that they want to memorise to a Favourite list. Thus, I created a Favorite button that works on two phases:
short-click to save the currently-view word into the Favourite list;
and long-click to view the Favourite list so that users can click on any words to look them up again.
I go for using a SQlite database to store the favourite words but I wonder how I can do this task. Specifically, my questions are:
Should I use the current dictionary SQLite database or create a new SQLite database to favorite words?
In each case, what codes do I have to write to cope with the mentioned task?
Could anyone there kindly help?
Here is the dictionary code:
package mydict.app;
import java.util.ArrayList;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.util.Log;
public class DictionaryEngine {
static final private String SQL_TAG = "[MyAppName - DictionaryEngine]";
private SQLiteDatabase mDB = null;
private String mDBName;
private String mDBPath;
//private String mDBExtension;
public ArrayList<String> lstCurrentWord = null;
public ArrayList<String> lstCurrentContent = null;
//public ArrayAdapter<String> adapter = null;
public DictionaryEngine()
{
lstCurrentContent = new ArrayList<String>();
lstCurrentWord = new ArrayList<String>();
}
public DictionaryEngine(String basePath, String dbName, String dbExtension)
{
//mDBExtension = getResources().getString(R.string.dbExtension);
//mDBExtension = dbExtension;
lstCurrentContent = new ArrayList<String>();
lstCurrentWord = new ArrayList<String>();
this.setDatabaseFile(basePath, dbName, dbExtension);
}
public boolean setDatabaseFile(String basePath, String dbName, String dbExtension)
{
if (mDB != null)
{
if (mDB.isOpen() == true) // Database is already opened
{
if (basePath.equals(mDBPath) && dbName.equals(mDBName)) // the opened database has the same name and path -> do nothing
{
Log.i(SQL_TAG, "Database is already opened!");
return true;
}
else
{
mDB.close();
}
}
}
String fullDbPath="";
try
{
fullDbPath = basePath + dbName + "/" + dbName + dbExtension;
mDB = SQLiteDatabase.openDatabase(fullDbPath, null, SQLiteDatabase.OPEN_READWRITE|SQLiteDatabase.NO_LOCALIZED_COLLATORS);
}
catch (SQLiteException ex)
{
ex.printStackTrace();
Log.i(SQL_TAG, "There is no valid dictionary database " + dbName +" at path " + basePath);
return false;
}
if (mDB == null)
{
return false;
}
this.mDBName = dbName;
this.mDBPath = basePath;
Log.i(SQL_TAG,"Database " + dbName + " is opened!");
return true;
}
public void getWordList(String word)
{
String query;
// encode input
String wordEncode = Utility.encodeContent(word);
if (word.equals("") || word == null)
{
query = "SELECT id,word FROM " + mDBName + " LIMIT 0,15" ;
}
else
{
query = "SELECT id,word FROM " + mDBName + " WHERE word >= '"+wordEncode+"' LIMIT 0,15";
}
//Log.i(SQL_TAG, "query = " + query);
Cursor result = mDB.rawQuery(query,null);
int indexWordColumn = result.getColumnIndex("Word");
int indexContentColumn = result.getColumnIndex("Content");
if (result != null)
{
int countRow=result.getCount();
Log.i(SQL_TAG, "countRow = " + countRow);
lstCurrentWord.clear();
lstCurrentContent.clear();
if (countRow >= 1)
{
result.moveToFirst();
String strWord = Utility.decodeContent(result.getString(indexWordColumn));
String strContent = Utility.decodeContent(result.getString(indexContentColumn));
lstCurrentWord.add(0,strWord);
lstCurrentContent.add(0,strContent);
int i = 0;
while (result.moveToNext())
{
strWord = Utility.decodeContent(result.getString(indexWordColumn));
strContent = Utility.decodeContent(result.getString(indexContentColumn));
lstCurrentWord.add(i,strWord);
lstCurrentContent.add(i,strContent);
i++;
}
}
result.close();
}
}
public Cursor getCursorWordList(String word)
{
String query;
// encode input
String wordEncode = Utility.encodeContent(word);
if (word.equals("") || word == null)
{
query = "SELECT id,word FROM " + mDBName + " LIMIT 0,15" ;
}
else
{
query = "SELECT id,content,word FROM " + mDBName + " WHERE word >= '"+wordEncode+"' LIMIT 0,15";
}
//Log.i(SQL_TAG, "query = " + query);
Cursor result = mDB.rawQuery(query,null);
return result;
}
public Cursor getCursorContentFromId(int wordId)
{
String query;
// encode input
if (wordId <= 0)
{
return null;
}
else
{
query = "SELECT id,content,word FROM " + mDBName + " WHERE Id = " + wordId ;
}
//Log.i(SQL_TAG, "query = " + query);
Cursor result = mDB.rawQuery(query,null);
return result;
}
public Cursor getCursorContentFromWord(String word)
{
String query;
// encode input
if (word == null || word.equals(""))
{
return null;
}
else
{
query = "SELECT id,content,word FROM " + mDBName + " WHERE word = '" + word + "' LIMIT 0,1";
}
//Log.i(SQL_TAG, "query = " + query);
Cursor result = mDB.rawQuery(query,null);
return result;
}
public void closeDatabase()
{
mDB.close();
}
public boolean isOpen()
{
return mDB.isOpen();
}
public boolean isReadOnly()
{
return mDB.isReadOnly();
}
}
And here is the code below the Favourite button to save to and load the Favourite list:
btnAddFavourite = (ImageButton) findViewById(R.id.btnAddFavourite);
btnAddFavourite.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// Add code here to save the favourite, e.g. in the db.
Toast toast = Toast.makeText(ContentView.this, R.string.messageWordAddedToFarvourite, Toast.LENGTH_SHORT);
toast.show();
}
});
btnAddFavourite.setOnLongClickListener(new View.OnLongClickListener() {
#Override
public boolean onLongClick(View v) {
// Open the favourite Activity, which in turn will fetch the saved favourites, to show them.
Intent intent = new Intent(getApplicationContext(), FavViewFavourite.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
getApplicationContext().startActivity(intent);
return false;
}
});
}

You need to have two tables
words
favorites
Words(id, word, meaning,...)
Favorites(id, word_id)
In the Favorites table have a foreign key that points the word from the Words Table.
I have only addressed the way you need to structure the table.
*EDITED*
words(id, name, meaning, timestamp)
favortie(id, word_id)