Been searching and using all the resources here but nothing seems to work with my project.
i need to retrieve a random data upon shaking the device.
i already have my shake detection.
my problem is i cant retrieve a random data.
tested on a device. the application crashes.
mainactivity.java
DataSource DS = new DataSource(this);
public void onShake(float force) {
// Called when Motion Detected
Toast.makeText(getBaseContext(), "Motion detected",
Toast.LENGTH_SHORT).show();
final Handler handler = new Handler();
handler.postDelayed(new Runnable() {
#Override
public void run() {
// Do something after 5s = 5000ms
TextView text = (TextView) findViewById(R.id.textView1);
text.setText(DS.getRandomQuote());
}
}, 2000);
public String getRandomQuote() {
Cursor c = database.query(MysqLiteHelper.TABLE_COMMENTS,
new String[] { MysqLiteHelper.COLUMN_COMMENT}, null, null, null, null, "ORDER BY RANDON() LIMIT 1");
if(c.moveToFirst())
return c.getString(c.getColumnIndex(MysqLiteHelper.COLUMN_COMMENT));
else
return "nothing";
}
Already Read:
How can select random data from database and display in textview?
and
How can select random data from database and display in textview?
but doesn't work for me
The function you're looking for is RANDOM() not RANDON()
query() takes its ORDER BY and LIMIT params in separate args, without the ORDER BY and LIMIT keywords.
Related
I have a JSON Array which consists of some contacts in my phonebook who are also users of my app. For example, the JSON Array might look like :
[{"contact_phonenumber":"11111"},{"contact_phonenumber":"22222"},{"contact_phonenumber":"33333"}]
phoneNumberofContact is a string which, in the do statement in my code below, returns every contact in my phone. How can I check which phoneNumberofContact numbers appear in my JSON Array and then, besides those contacts in the ListView put the words '- app user'. My ListView is working fine, I just want to add this feature in.
So, for example, for the number 11111 I would have in my ListView :
Joe Blogs - app user
11111
Here's my code:
JSONArray jsonArrayContacts = response;
//response is something like [{"contact_phonenumber":"11111"}, etc...]
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_new_contact);
//selectPhoneContacts is an empty array list that will hold our SelectPhoneContact info
selectPhoneContacts = new ArrayList<SelectPhoneContact>();
listView = (ListView) findViewById(R.id.listviewPhoneContacts);
}
//******for the phone contacts in the listview
// Load data in background
class LoadContact extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected Void doInBackground(Void... voids) {
// we want to delete the old selectContacts from the listview when the Activity loads
// because it may need to be updated and we want the user to see the updated listview,
// like if the user adds new names and numbers to their phone contacts.
selectPhoneContacts.clear();
// we have this here to avoid cursor errors
if (cursor != null) {
cursor.moveToFirst();
}
try {
// get a handle on the Content Resolver, so we can query the provider,
cursor = getApplicationContext().getContentResolver()
// the table to query
.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
null,
null,
null,
// display in ascending order
ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME + " COLLATE LOCALIZED ASC");
// get the column number of the Contact_ID column, make it an integer.
// I think having it stored as a number makes for faster operations later on.
// get the column number of the DISPLAY_NAME column
int nameIdx = cursor.getColumnIndex(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME);
// get the column number of the NUMBER column
int phoneNumberofContactIdx = cursor.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER);
cursor.moveToFirst();
// We make a new Hashset to hold all our contact_ids, including duplicates, if they come up
Set<String> ids = new HashSet<>();
do {
System.out.println("=====>in while");
// get a handle on the display name, which is a string
name = cursor.getString(nameIdx);
// get a handle on the phone number, which is a string
phoneNumberofContact = cursor.getString(phoneNumberofContactIdx);
//----------------------------------------------------------
// get a handle on the phone number of contact, which is a string. Loop through all the phone numbers
// if our Hashset doesn't already contain the phone number string,
// then add it to the hashset
if (!ids.contains(phoneNumberofContact)) {
ids.add(phoneNumberofContact);
SelectPhoneContact selectContact = new SelectPhoneContact();
selectContact.setName(name);
selectContact.setPhone(phoneNumberofContact);
selectPhoneContacts.add(selectContact);
}
} while (cursor.moveToNext());
} catch (Exception e) {
Toast.makeText(NewContact.this, "what the...", Toast.LENGTH_LONG).show();
e.printStackTrace();
// cursor.close();
} finally {
}
if (cursor != null) {
cursor.close();
}
return null;
}
#Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
adapter = new SelectPhoneContactAdapter(selectPhoneContacts, NewContact.this);
// we need to notify the listview that changes may have been made on
// the background thread, doInBackground, like adding or deleting contacts,
// and these changes need to be reflected visibly in the listview. It works
// in conjunction with selectContacts.clear()
adapter.notifyDataSetChanged();
listView.setAdapter(adapter);
}
}
In the first, you can parse the jsonArrayContacts to a List:
final List<String> responseContacts = new ArrayList<String>();
try {
JSONArray responseObject = new JSONArray(response);
for (int i = 0; i < responseObject.length(); i++) {
final JSONObject obj = responseObject.getJSONObject(i);
responseContacts.add(obj.getString("contact_phonenumber"));
}
// System.out.println("the matching contacts of this user are :" + responseContacts);
} catch(Exception e) {
e.printStackTrace();
}
after you get your local contacts, then you have two sets of contacts, so it's easy to check which number appears in your json array contacts.
And then you can pass the responseContacts into SelectPhoneContactAdapter during you initialize it, and in getView() method of the adapter, you can know whether you need to put the words '- app user' to your item view or not.
I created a database with a table named flagTable, this table only has two fields, which are id(auto increment) and an integer field. Next, in my program, I have a button that will trigger a thread to start. When the thread is starting, it constantly retrieve data from database, and check for the for the value, if the value is equal to one then it will trigger another new Thread, something like this:
private class statusOfStrummingInAnotherDevice extends Thread {
int value;
public void run() {
try{
while(true){
try{
if(flagCursor == null){
flagCursor = cdb1.getFlagAll();
}
}catch(Exception e){break;}
try{
Log.i("MAIN3ACTIVITY","getting status");
int size = cdb1.getSize(flagCursor);
Log.i("MAIN3ACTIVITY","SIZE is" + String.valueOf(xyz));
for(int i = 0 ; i < size ; i++){
flagCursor.moveToPosition(i);
Log.i("MAIN3ACTIVITY","getting status jkasdfasdf");
value = cdb1.getFlag();
if(value == 1){
Log.i("FLAGCURSOR=====>>>>","Succesful");
releasingNotes = new ReleasingNotes(IntendedChord);
releasingNotes.start();
//break;
}
cdb1.updateFlag(0);
Log.i("FLAGCURSOR=====>>>>",String.valueOf(value));
}
flagCursor = null;
}catch(Exception e){break;}
Log.i("MAIN3ACTIVITY","thread is sleeping");
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
break;
}
}
}catch(Exception e){
}
}
}
In the meantime, the data that were retrieved from the database is using this function:
public Cursor getFlagAll(){
return getReadableDatabase().rawQuery(
"SELECT _ID, flag from flagTable", null);
}
And, the data that were updated to the database through this method:
public int updateFlag(int i) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put("flag",i);
return db.update("flagTable" , contentValues , "_ID" + "= ?",new String[]{String.valueOf(1)});
}
Now, above codes will give no error, however, the data that were retrieved from the database is always 1, it keeps trigger a new function. In my above codes, I stated if the value is equal to 1, then the current thread will trigger a new thread to start, When its finished, the program will update the current data to 0. So that, the next round of the infinite loop can stop triggering new thread until a the conditon is met. What is problem overhere? did my codes really updated the new value? or I need to referesh the database every time I updated a new value.
Use Listeners to your database.
use SQLiteTransactionListener and do your things in onCommit()
Some guide in details here :
https://developer.android.com/reference/android/database/sqlite/SQLiteTransactionListener.html and
http://www.programcreek.com/java-api-examples/index.php?api=android.database.sqlite.SQLiteTransactionListener
Many people said that SQLiteDatabase is thread-safe,but ,when i ran some simple tests with setup like this:
private class MyRunnable implements Runnable{
#Override
public void run() {
for(int i = 0 ;i < 100 ; i++){
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
Cursor cursor = database.query(true,"testdb",new String[]{"num"},"id=?",
new String[]{"1"},null,null,null,null);
cursor.moveToFirst();
int original = cursor.getInt(0);
ContentValues values = new ContentValues();
values.put("num",++original);
database.update("testdb",values,"id=?",new String[]{"1"});
}
}
}
MyRunnable runnable1 = new MyRunnable();
MyRunnable runnable2 = new MyRunnable();
new Thread(runnable1).start();
new Thread(runnable2).start();
In MyRunnable ,there is a loop that runs 100 times. Each time, the num field will add by 1 and the num's initial value is 0. we can see that the above code's expected result is 200,but i only get 197.
so does that mean SQLiteDatabase is not thread-safe?
No, the way you are handling the data is just not thread-safe. You could use an atomic SQL-query like:
UPDATE table SET num = num + 1
Instead of retrieving the data in your application code, modifying it and storing it back.
SQLite being threadsafe means that you can safely use all SQLite functions in multiple threads at once, it does not mean the database gets locked automatically depending on what you are doing. If your thread gets interrupted anywhere between the query() call and the update() call, returning to the thread at that point will mean the data you retrieved earlier is no longer up to date.
I have read several posts here on speed issues when looping through a cursor and tried the answers given in these posts such as e.g. do not use getcolumnindex in the loop call this once etc.
However with a database having around 2400 records it takes around 3 to 5 minutes to finish.
The loop is running in an async task method so that it does not hang up the device and the database is handled via a database adapter.
The loop code is as follows :
while (!exportrec.isAfterLast()) {
if ( exportrec.moveToNext() ) {
fulldate = exportnumberformatter(exportrec.getInt(daye))
+"/"+exportnumberformatter(exportrec.getInt(monthe))+"/"
+String.valueOf(exportrec.getInt(yeare));
fulltime = exportnumberformatter(exportrec.getInt(houre))+":"
+exportnumberformatter(exportrec.getInt(mine))+":"
+exportnumberformatter(exportrec.getInt(sece));
noiseid = exportrec.getInt(typee);
exportedinfo += exporttypes[id] +","+exportrec.getString(notee)+","+
fulldate+","+fulltime+" \n" ;
}
}
The exportnumberformatter does the following :
public String exportnumberformatter(int i) {
String result = Integer.toString(i);
if (result.length() >1 ) {
return Integer.toString(i);
}
String zeroprefix = "";
zeroprefix = "0"+result;
return zeroprefix ;
}
The cursor is called as follows before the loop to get the data :
exportrec = MD.GetAllLogs(2, "date_sort");
exportrec.moveToFirst();
The MD is the database adapter and the GetAllLogs Method (this has been played with to try and speed things up and so the date_sort that is used is really ignored here):
public Cursor GetAllLogs(Integer i,String sortfield)
{
String sorted = "";
if (i == 1 ) {
sorted = "DESC";
} else if (i == 2) {
sorted = "ASC";
}
return mDB.query(DB_TABLE, new String[] {COL_ID, COL_TYPE,COL_IMAGE, COL_INFO,COL_IMAGE,COL_HOUR,COL_SEC,COL_MIN,COL_DAY,COL_MON,COL_YEAR,COL_SORT_DATE},
null, null, null, null, COL_ID+" "+sorted);
}
When I created the table in the database it had no indexes so I created these via the upgrade method. However they did not error or appear to fail when I did this but what I do not know is A) does the database/table need rebuilding after an index is created and B) how to tell if they have been created ? the two indexes were based on the ID as the first and a field that holds the year month day hour minute second all in on Long Integer.
I am concerned that the loop appears to be taking this long to read through that many records.
Update:
rtsai2000's and the suggestion from CL answer has improved the speed from minutes to seconds
Your exportedInfo String is growing and growing. Save the results in an array and Stringify later (such as with StringBuilder).
You are not closing your cursor after reading the records.
List<String> exportedInfo = new ArrayList<String>();
Cursor exportrec = GetAllLogs();
try {
while (exportrec.moveToNext()) {
String info = String.format("%s, %s, %02d/%02d/%02d, %02d:%02d:%02d",
exporttypes[id],
exportrec.getString(notee),
exportrec.getInt(daye),
exportrec.getInt(monthe),
exportrec.getInt(yeare),
exportrec.getInt(houre),
exportrec.getInt(mine),
exportrec.getInt(sece));
exportedInfo.add(info);
}
} finally {
exportrec.close();
}
return exportedInfo;
I have a database with some records in and i have the code i wish to execute on each row but I'm having trouble creating a suitable loop, ive been trying while(movetonext) but it hasnt been working.
cursor = getAppts();
cursor.moveToNext();
String titlefromdb = cursor.getString(3);
if (strTitle.equals(titlefromdb) && cursor.getString(1).equals(dateselforap))
{
// matching code update box
final Dialog matchdiag = new Dialog(CW2Organisor.this);
matchdiag.setContentView(R.layout.apptmatch);
matchdiag.setTitle("View/Edit Appointment");
matchdiag.setCancelable(true);
TextView matchtxt = (TextView) matchdiag.findViewById(R.id.matchtxt);
matchtxt.setText("Appointment \"" + titlefromdb + "\" already exists, please choose a different event title");
Button btnmatchok = (Button) matchdiag.findViewById(R.id.btnmatch);
btnmatchok.setOnClickListener(new OnClickListener() {
// on click for cancel button
#Override
public void onClick(View v) {
matchdiag.dismiss();
}
});
matchdiag.show();
}
else
{
addAppt(strTime, strTitle, strDet);
dialog.dismiss();
}
What I would need is for each row of my database i would need the titlefromdb to hold the title field of the current row and the for the if statement to run and then move to the next row.
You could try
cursor.moveToFirst();
loop with some sort of check
cursor.moveToNext();
end loop
... and I would also try to qualify your "it's not working" statement. What's not working?