Develop Reference

Android Fill Text String from SQLite Database

I use a string to populate a textview on an listview
String[] text1 = { "Afghanistan", "Algeria" ,"Fred"};
I want to replace the 3 strings in the string array with data from a database. I have tried the following
String text1[];
DBAdapter db = new DBAdapter(this);
db.open();
Cursor c = db.getAsset3();
int counter = 0;
while (c.moveToNext()) {
text1[counter]=c.getString(0);
counter++;
}
getAsset3 from DBAdapter
public Cursor getAsset3() throws SQLException
{
Cursor mCursor =
db.query(true, "SURVDAT", new String[] {KEY_SR1,KEY_SR2,KEY_SR3,KEY_SR4,KEY_SR5,KEY_SR6,KEY_SR7}, null, null,null, null, null, null);
if (mCursor != null) {
//mCursor.moveToFirst();
}
return mCursor;
}
When I run the app crashes saying Null PointerException
Any ideas where I'm going wrong?
Any help Appreciated
Mark

You didn't initialize text1 in your second snippet, so when you type text1[counter] = c.getString(0); you are trying to get counter'th index of null
You shall do something like
DBAdapter db = new DBAdapter(this);
db.open();
Cursor c = db.getAsset3();
String text1[] = new String[c.getCount()];
for(int i = 0; cursor.moveToNext(); ++i)
{
text1[i] = c.getString(0);
}
cursor.close();

Android IllegalStateException: attempt to re-open an already-closed object: SQLiteDatabase [duplicate]

This question already has an answer here:
attempt to re-open an already-closed object: SQLiteDatabase
(1 answer)
Closed 8 years ago.
I know there are several questions like this one, but all of them seem to have a different approach to solve the problem and none have solved mine.
I have my main activity working just fine, loading the db and populating the listview. Then I call a second activity and the problem shows up when I try to load the listview.
I have tried using start/stop managingcursor(cursor) even though it is deprecated, but it didn't fix the problem. Also I tried cloasing the cursor and db in my main activity before firing the next one but that didn't help either.
Both classes extend from ListActivity and follow the same sequence:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Open db in writing mode
MySQLiteHelper.init(this);
MySQLiteHelper tpdbh =
new MySQLiteHelper(this, "DB", null, 1);
SQLiteDatabase db = tpdbh.getWritableDatabase();
checkLocationAndDownloadData(); //this fires a Asynctask that calls method parseNearbyBranches shown bellow
//I load the data to the ListView in the postExecute method of the asynctask by calling:
/*
Cursor cursor = MysSQLiteHelper.getBranchesNames();
adapter = new SimpleCursorAdapter(this,
R.layout.row, cursor, fields, new int[] { R.id.item_text },0);
setListAdapter(adapter);
*/
ListView lv = getListView();
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> listView, View view,
int position, long id) {
// Get the cursor, positioned to the corresponding row in the result set
Cursor cursor = (Cursor) listView.getItemAtPosition(position);
// Get the state's capital from this row in the database.
String branch_id = cursor.getString(cursor.getColumnIndexOrThrow("branch_id"));
cursor.close();
openNextActivity(Integer.parseInt(branch_id));
}
});
}
//In another file:
private void parseNearbyBranches(JSONObject jo) throws JSONException
{
if ( jo.has(jsonTitle) &&
jo.has("company_id") &&
jo.has("id")
) {
String branch = jo.getString(jsonTitle);
MySQLiteHelper tpdbh = MySQLiteHelper.instance;
SQLiteDatabase db = tpdbh.getWritableDatabase();
db.execSQL("INSERT INTO Branches (branch_id, name, company_id) " +
"VALUES ('" +jo.getInt("id")+"', '" + branch +"', '" +jo.getInt("company_id")+"' )");
db.close(); //no difference is I comment or uncomment this line
}
}
In MySQLiteHelper.java:
public static Cursor getBranchesNames() {
// TODO Auto-generated method stub
String[] columns = new String[] { "_id", "branch_id", "name", "company_id" };
Cursor c = getReadDb().query(branchesTable, columns, null, null, null, null,
null);
return c;
}
My other activity does basically the same:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_branch_surveys);
//Read branch data from DB
int companyID = -1;
MySQLiteHelper.init(this);
String [] columns = new String [] {"company_id"};
String [] args = {Integer.toString(branchID)};
Cursor c = MySQLiteHelper.getReadDb().query(MySQLiteHelper.branchesTable, columns, "branch_id=?", args, null, null, null); //THIS QUERY WORKS JUST FINE
if (c.moveToFirst())
companyID = Integer.parseInt(c.getString(0));
c.close();
if( companyID != -1)
{
new DownloadTask().execute(Integer.toString(companyID) );
//where the Async task calls something just like NearByBranches shown above(but with different objects of course)
//And the postExecute sets the listView:
/* cursor = MySQLiteHelper.getAll();
SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,
R.layout.row, cursor, fields, new int[] { R.id.item_text },0);
setListAdapter(adapter);
*/
}
}
}
In MySQLiteHelper.java:
public static Cursor getAll() {
// TODO Auto-generated method stub
String[] columns = new String[] { "_id","title", "points" };
//********IT IS IN THIS LINE WHERE I GET THE ERROR:********************
Cursor c = getReadDb().query(theTable, columns, null, null, null, null,
null);
return c;
}
public static SQLiteDatabase getReadDb() {
if (null == db) {
db = instance.getReadableDatabase();
}
return db;
}
I hope you can help me out. Thanks!

I just tried commenting the db.close in the similar method of parseNeabyBranches and the problem was solved. Yet I dont get the same error having db.close() in parseNearbyBranches(), can you explain me why?
In parseNearbyBranches() you create a separate SQLiteDatabase object with:
SQLiteDatabase db = tpdbh.getWritableDatabase();
Since this is a different object than the one returned by getReadDb(), you can (and should) close it. The basic rule is each time you call getWritableDatabase() and getReadableDatable() you must have a matching close() statement.

Android SQLite get data from database to an array

i want to get the value from the cursor without the SimpleCursorAdapter part.here is the code
public Cursor queueAll(){
String[] columns = new String[]{KEY_ID, KEY_CONTENT1, KEY_CONTENT2,KEY_CONTENT3};
Cursor cursor = sqLiteDatabase.query(MYDATABASE_TABLE, columns,
null, null, null, null, null);
return cursor;
}
and the activity side code
cursor = mySQLiteAdapter.queueAll();
from = new String[]{SQLiteAdapter.KEY_ID, SQLiteAdapter.KEY_CONTENT1, SQLiteAdapter.KEY_CONTENT2, SQLiteAdapter.KEY_CONTENT3};
int[] to = new int[]{R.id.id, R.id.text1, R.id.text2,R.id.text3};
cursorAdapter =
new SimpleCursorAdapter(this, R.layout.row, cursor, from, to);
listContent.setAdapter(cursorAdapter);
while(!cursor.isAfterLast())
{
String tilt = cursor.getString(cursor.getColumnIndex(SQLiteAdapter.KEY_CONTENT1));
String pkg = cursor.getString(cursor.getColumnIndex(SQLiteAdapter.KEY_CONTENT3));
if(tilt.equals("LEFT"))
{
Log.v("LEFT",pkg);
}
else if(tilt.equals("RIGHT"))
{
Log.v("RIGHT",pkg);
}
cursor.moveToNext();
}
i am getting the pkg value correct.but i want to get the values directly from the cursor while removing SimpleCursorAdapter part the code doesn't work.
any help would be appreciated :)

You can get values without declaring adapters. Adapters are need if you want to show the data in the list widgets. So your can be the following:
cursor = mySQLiteAdapter.queueAll();
if (cursor == null) {
//check if there are errors or query just return null
}
if (cursor.moveToFirst()) {
while(!cursor.isAfterLast())
{
String tilt = cursor.getString(cursor.getColumnIndex(SQLiteAdapter.KEY_CONTENT1));
String pkg = cursor.getString(cursor.getColumnIndex(SQLiteAdapter.KEY_CONTENT3));
if(tilt.equals("LEFT"))
{
Log.v("LEFT",pkg);
}
else if(tilt.equals("RIGHT"))
{
Log.v("RIGHT",pkg);
}
cursor.moveToNext();
}
}

First you must count how many rows are in your table. Then assign that count to variable and it use to create an array. For array size you can use that count variable. Then create a for loop and use that count variable for rounds. After create your query and assign values to your arrays. 100% worked!.
int sqlcount;
Cursor mFetch;
SQLiteDatabase mydb = openOrCreateDatabase("your database name", MODE_PRIVATE, null);
mydb.execSQL("create table if not exists customer(name varchar,email varchar)");
Cursor mCount = mydb.rawQuery("select count(*) from customer", null);
mCount.moveToFirst();
sqlcount = mCount.getInt(0);
mCount.close();
String cname[] = new String[sqlcount];
String cemail[] = new String[sqlcount];
for(int i=0;i<sqlcount;i++) {
mFetch= mydb.rawQuery("select name,email from customer", null);
mFetch.moveToPosition(i);
cname[i] = mFetch.getString(0);
cemail[i] = mFetch.getString(1);
}
mFetch.close();
Toast.makeText(MainActivity.this,String.valueOf(cname[0]),Toast.LENGTH_SHORT).show();
Toast.makeText(MainActivity.this,String.valueOf(cemail[1]),Toast.LENGTH_SHORT).show();

How to access particular column value in android sqlite application?

I have an application where I want to use the values returned from an SQL query against a database in my application. I want to use attach these values to a uri that links to a script on remote host. I am doing a call to the method to retrieve the values, after which I will now extract them. The issue is that I am facing a challenge in going about this. I know a bit of php and what I want in android is done like this in php:
....(preceding code)...$row['email'];
and I can now assign a variable e.g. $email=$row['email'];
How can I do this in android?
I don't want a cursor returned, just the values of the columns as strings.
Below is my code (I will need help to retrieve the password column)
public String[] selectAll()
{
Cursor cursor = db.query(DB_TABLE_NAME, new String[] { "email","password"},null, null, null, null,null);
if(cursor.getCount() >0)
{
String[] str = new String[cursor.getCount()];
int i = 0;
while (cursor.moveToNext())
{
str[i] = cursor.getString(cursor.getColumnIndex("email"));
i++;
}
return str;
}
else
{
return new String[] {};
}
}
I need help on inserting the "password" column so that it will be returned with the email.

try this way
String[][] str = new String[cursor.getCount()][cursor.getColumnCount()];
while (cursor.moveToNext())
{
for(int j=0;j<cursor.getColumnCount();j++)
str[i][j] = cursor.getString(j); /// may be this column start with the 1 not with the 0
i++;
}
you need to store this in two dimenstion array for row wise and column wise
but if this will give only one result everytime
String[] str = new String[cursor.getColumnCount()]; // here you have pass the total column value
while (cursor.moveToNext())
{
str[0] = cursor.getString(cursor.getColumnIndex("email"));
str[1] = cursor.getString(cursor.getColumnIndex("password"));
}

You should change your design like this
public Cursor selectAll() {
Cursor cursor = db.query(DB_TABLE_NAME, new String[] { "email","password"},null, null, null, null,null);
return cursor;
}
and use the selectAll function like this
Cursor cursor=selectAll();
String[] mail = new String[cursor.getCount()];
String[] pass = new String[cursor.getCount()];
int i=0;
while (cursor.moveToNext())
{
mail[i] = cursor.getString(cursor.getColumnIndex("email"));
pass[i] = cursor.getString(cursor.getColumnIndex("password"));
i++;
}

Iterate through rows from Sqlite-query

I have a table layout that I want to populate with the result from a database query. I use a select all and the query returns four rows of data.
I use this code to populate the TextViews inside the table rows.
Cursor c = null;
c = dh.getAlternative2();
startManagingCursor(c);
// the desired columns to be bound
String[] columns = new String[] {DataHelper.KEY_ALT};
// the XML defined views which the data will be bound to
int[] to = new int[] { R.id.name_entry};
SimpleCursorAdapter mAdapter = new SimpleCursorAdapter(this,
R.layout.list_example_entry, c, columns, to);
this.setListAdapter(mAdapter);
I want to be able to separate the four different values of KEY_ALT, and choose where they go. I want them to populate four different TextViews instead of one in my example above.
How can I iterate through the resulting cursor?

Cursor objects returned by database queries are positioned before the first entry, therefore iteration can be simplified to:
while (cursor.moveToNext()) {
// Extract data.
}
Reference from SQLiteDatabase.

You can use below code to go through cursor and store them in string array and after you can set them in four textview
String array[] = new String[cursor.getCount()];
i = 0;
cursor.moveToFirst();
while (!cursor.isAfterLast()) {
array[i] = cursor.getString(0);
i++;
cursor.moveToNext();
}

for (boolean hasItem = cursor.moveToFirst(); hasItem; hasItem = cursor.moveToNext()) {
// use cursor to work with current item
}

Iteration can be done in the following manner:
Cursor cur = sampleDB.rawQuery("SELECT * FROM " + Constants.TABLE_NAME, null);
ArrayList temp = new ArrayList();
if (cur != null) {
if (cur.moveToFirst()) {
do {
temp.add(cur.getString(cur.getColumnIndex("Title"))); // "Title" is the field name(column) of the Table
} while (cur.moveToNext());
}
}

Found a very simple way to iterate over a cursor
for(cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext()){
// access the curosr
DatabaseUtils.dumpCurrentRowToString(cursor);
final long id = cursor.getLong(cursor.getColumnIndex(BaseColumns._ID));
}

I agree to chiranjib, my code is as follow:
if(cursor != null && cursor.getCount() > 0){
cursor.moveToFirst();
do{
//do logic with cursor.
}while(cursor.moveToNext());
}

public void SQLfunction() {
SQLiteDatabase db = getReadableDatabase();
SQLiteQueryBuilder qb = new SQLiteQueryBuilder();
String[] sqlSelect = {"column1","column2" ...};
String sqlTable = "TableName";
String selection = "column1= ?"; //optional
String[] selectionArgs = {Value}; //optional
qb.setTables(sqlTable);
final Cursor c = qb.query(db, sqlSelect, selection, selectionArgs, null, null, null);
if(c !=null && c.moveToFirst()){
do {
//do operations
// example : abcField.setText(c.getString(c.getColumnIndex("ColumnName")))
}
while (c.moveToNext());
}
}
NOTE: to use SQLiteQueryBuilder() you need to add
compile 'com.readystatesoftware.sqliteasset:sqliteassethelper:+'
in your grade file