Develop Reference

How to get a single SQLite row data with its id?

I have successfully retrieved SQLite data to ListView. Now I am trying to implement OnItemClickListener to show the data in Dialog but I am getting this error
2019-04-08 18:42:53.020 20591-20591/com.app E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.app, PID: 20591
java.lang.NullPointerException: Attempt to invoke virtual method 'java.io.File android.content.Context.getDatabasePath(java.lang.String)' on a null object reference
at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:292)
at android.database.sqlite.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:262)
at com.app.SQLiteAdaptor.GetUserByUserId(SQLiteAdaptor.java:99)
at com.app.OrderHistory$1.onItemClick(OrderHistory.java:64)
at android.widget.AdapterView.performItemClick(AdapterView.java:318)
at android.widget.AbsListView.performItemClick(AbsListView.java:1181)
at android.widget.AbsListView$PerformClick.run(AbsListView.java:3165)
at android.widget.AbsListView$3.run(AbsListView.java:4147)
at android.os.Handler.handleCallback(Handler.java:794)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:173)
at android.app.ActivityThread.main(ActivityThread.java:6634)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:822)
This is where I need to retrieve row
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
final Dialog fullscreenDialog = new Dialog(getApplicationContext(), R.style.Dialog);
fullscreenDialog.setContentView(R.layout.dialog_oh);
SQLiteAdaptor db = new SQLiteAdaptor(c);
ArrayList<HashMap<String, String>> userList = db.GetUserByUserId(i); //Line 64
HashMap<String, String> hashDetails = userList.get(0);
//Use this index accordingly
tvit.setText(hashDetails.get("item"));
tvpr.setText(hashDetails.get("price"));
tvqu.setText(hashDetails.get("quantity"));
tvad.setText(hashDetails.get("address"));
tvna.setText(hashDetails.get("name"));
tvem.setText(hashDetails.get("email"));
tvtim.setText(hashDetails.get("time"));
fullscreenDialog.show();
}
});
Here is the SQLiteAdaptor get row data by id method snippet
public ArrayList<HashMap<String, String>> GetUserByUserId(int userid ){
SQLiteDatabase db = this.getReadableDatabase(); \\Line 99
ArrayList<HashMap<String, String>> userList = new ArrayList<>();
String query = "SELECT item, price, quantity, name, address, email, orderid FROM "+ Table_Name;
Cursor cursor = db.query(Table_Name, new String[]{COL_2, COL_3, COL_4, COL_5, COL_6, COL_7, COL_8, COL_9}, COL_1+ "=?",new String[]{String.valueOf(userid)},null, null, null, null);
if (cursor.moveToNext()){
HashMap<String,String> user = new HashMap<>();
user.put("item",cursor.getString(cursor.getColumnIndex(COL_2)));
user.put("price",cursor.getString(cursor.getColumnIndex(COL_3)));
user.put("quantity",cursor.getString(cursor.getColumnIndex(COL_4)));
user.put("name",cursor.getString(cursor.getColumnIndex(COL_5)));
user.put("address",cursor.getString(cursor.getColumnIndex(COL_6)));
user.put("email",cursor.getString(cursor.getColumnIndex(COL_7)));
user.put("orderid",cursor.getString(cursor.getColumnIndex(COL_8)));
user.put("time",cursor.getString(cursor.getColumnIndex(COL_9)));
userList.add(user);
}
return userList;
}
And it is not null pointer exception because I am nit getting any error while retrieving data in Listview
Or any other way to how to retrieve row with its id
Any help and solutions are appreciated
Thanks in advance

Try this
SQLiteAdaptor db = new SQLiteAdaptor(view.getContext());

Database query on a specific row

I am building a blood bank database app. Where I will take some info along with blood type. I store the blood type as "INTEGER NOT NULL" with 1, 2,....,7 which indicate A+,.....,AB- blood types. But when I try to query a listview according to the user select the blood group from a spinner, I get errors(stack trace is given below). Inserting data in the database doing great without giving an error.
MainActivity relevant code -
private void displayDatabaseInfo(){
String[] projection = {
DonorEntry.COLUMN_DONOR_NAME,
DonorEntry.COLUMN_DONOR_MOBILE,
DonorEntry.COLUMN_BLOOD_GROUP,
DonorEntry.COLUMN_DONATE_DATE };
String selection = DonorEntry.COLUMN_BLOOD_GROUP + "=?";
String [] selectionArgs = new String[] {getString(mBloodType)};
Cursor cursor = getContentResolver().query(DonorEntry.CONTENT_URI,
projection, selection, selectionArgs,null);
ListView listView = (ListView) findViewById(R.id.list);
DonorCursorAdapter adapter = new DonorCursorAdapter(this, cursor);
listView.setAdapter(adapter);
}
DonorCursorAdapter relevant code -
#Override
public void bindView(View view, Context context, Cursor cursor) {
// Find individual views that we want to modify in the list item layout
TextView nameTextView = (TextView) view.findViewById(R.id.name);
TextView mobileTextView = (TextView) view.findViewById(R.id.mobileNo);
TextView bloodTypeTextView = (TextView) view.findViewById(R.id.bloodType);
TextView lastDonateTextView = (TextView) view.findViewById(R.id.donateDate);
// Find the columns of donor's attributes that we're interested in
int nameColumnIndex = cursor.getColumnIndex(DonorEntry.COLUMN_DONOR_NAME);
int mobileColumnIndex = cursor.getColumnIndex(DonorEntry.COLUMN_DONOR_MOBILE);
int bloodTypeColumnIndex = cursor.getColumnIndex(DonorEntry.COLUMN_BLOOD_GROUP);
int lastDonateColumnIndex = cursor.getColumnIndex(DonorEntry.COLUMN_DONATE_DATE);
// Read the donor attributes from the Cursor for the current pet
String donorName = cursor.getString(nameColumnIndex);
String donorMobileNo = cursor.getString(mobileColumnIndex);
String donorBloodType = cursor.getString(bloodTypeColumnIndex);
String donorLastDonate = cursor.getString(lastDonateColumnIndex);
// Update the TextViews with the attributes for the current pet
nameTextView.setText(donorName);
mobileTextView.setText(donorMobileNo);
bloodTypeTextView.setText(donorBloodType);
lastDonateTextView.setText(donorLastDonate);
}
Stack trace
<code>
2019-03-02 17:25:37.140 28705-28705/com.sarkerjr.greenBlood E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.sarkerjr.greenBlood, PID: 28705
android.content.res.Resources$NotFoundException: String resource ID #0x2
at android.content.res.Resources.getText(Resources.java:339)
at android.content.res.Resources.getString(Resources.java:433)
at android.content.Context.getString(Context.java:556)
at com.sarkerjr.greenBlood.MainActivity.displayDatabaseInfo(MainActivity.java:121)
at com.sarkerjr.greenBlood.MainActivity.access$000(MainActivity.java:21)
at com.sarkerjr.greenBlood.MainActivity$2.onClick(MainActivity.java:56)
at android.view.View.performClick(View.java:6294)
at android.view.View$PerformClick.run(View.java:24770)
at android.os.Handler.handleCallback(Handler.java:790)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
</code>

Here fixed everything for you. There were a few problems.
getString was crashing. This is not the method you want to use to parse any integer, it is used to get a resource and you pass an id of that resource.
CursorAdapter needs _id column inside the cursor and when you passed projection array without _id column, your adapter was crashing. So I removed the projection and now you will get all the columns.
Although this was working somehow but you should not use getString when column value type is INTEGER, so I changed it to getInt.
You were directly assigning the column value to the TextView which was showing integers, so I created a method in MainActivity to get the actual values of blood types.
MainActivity changes -
private void displayDatabaseInfo() {
String selection = DonorEntry.COLUMN_BLOOD_GROUP + "=?";
String[] selectionArgs = new String[]{String.valueOf(mBloodType)};
Cursor cursor = getContentResolver().query(DonorEntry.CONTENT_URI,
null, selection, selectionArgs, null);
ListView listView = findViewById(R.id.list);
DonorCursorAdapter adapter = new DonorCursorAdapter(this, cursor);
listView.setAdapter(adapter);
}
// Get value of readable blood type
public String getBloodTypeString(int bloodType) {
switch (bloodType) {
case A_Positive:
return getResources().getString(R.string.a_positive);
case A_Negative:
return getResources().getString(R.string.a_negative);
case B_Positive:
return getResources().getString(R.string.b_positive);
case B_Negative:
return getResources().getString(R.string.b_negative);
case O_Positive:
return getResources().getString(R.string.o_positive);
case O_Negative:
return getResources().getString(R.string.o_negative);
case AB_Positive:
return getResources().getString(R.string.ab_positive);
case AB_Negative:
return getResources().getString(R.string.ab_negative);
default:
return "UNKNOWN";
}
}
DonorCursorAdapter changes -
int donorBloodType = cursor.getInt(bloodTypeColumnIndex);
String donorBloodTypeString;
try {
donorBloodTypeString = ((MainActivity) context).getBloodTypeString(donorBloodType);
} catch (ClassCastException e) {
throw new ClassCastException("Trying to access MainActivity method from different context");
}
bloodTypeTextView.setText(donorBloodTypeString);

Call
String [] selectionArgs = new String[] {String.valueOf(mBloodType)};
instead of
String [] selectionArgs = new String[] {getString(mBloodType)};

Android MatrixCursor

I am trying to get a basic matrix cursor running, but for some reason the list remains empty. Would appreciate if someone could spot what may be wrong with the code?
String []columns = new String[] {"_id","Title","Desc"} ;
MatrixCursor mc = new MatrixCursor(columns);
startManagingCursor(mc);
for(int i=0; i< 200;i++)
{
mc.addRow(new Object[]{i, "test"+i ,"..."});
}
ListView lv = (ListView)findViewById(R.id.alist);
int [] r = new int[1];
r[0] = R.id.atext; // the id of the textview in test_list_item layout
String [] s= new String[1];
s[0] = mc.getColumnName(1); // the column to be used "Title"
SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,android.R.layout.test_list_item,mc,s,r);
lv.setAdapter(adapter);

The reason the layout was not read was due to the incorrect layout being called:
SimpleCursorAdapter(this,android.R.layout.list_item,mc,s,r);
Instead of:
SimpleCursorAdapter(this,R.layout.my_list_item,mc,s,r);

Get spacial content of selected item in listview in android

I am new with android programing and I have a problem with list view
In my app I have to read data from database (name,ID,year) and then add them to listview after that user must select one of
the items and in a new activity again I read data from db and list some of the other Items based on user's selection
Ol at this time In my first activity I read data and add them to listview..To select I must define a listener..right?
I define it like this code
enter code here #Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_read_book);
String SDcardPath = Environment.getExternalStorageDirectory().getPath();
String DbPath = SDcardPath + "/Tosca/" + "persian_poem.db";
ListView list = (ListView) findViewById(R.id.list_poet_name);
try {
db = SQLiteDatabase.openDatabase(DbPath,null,SQLiteDatabase.CREATE_IF_NECESSARY);
getData();
db.close();
}
catch (SQLiteException e) {
Toast.makeText(this, e.getMessage(), 1).show();
}
list.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View v, int position,
long id) {
// TODO Auto-generated method stub
ListView list = (ListView) findViewById(R.id.list_poet_name);
Log.i(TAG, "Listview get Item Pos");
Peot_ID.putString ("Peot_ID", (String) list.getItemAtPosition(position));
Intent Book_list_intent = new Intent (Read.this,Book_list.class);
Book_list_intent.putExtras(Peot_ID);
startActivity(Book_list_intent);
}
});
}
private void getData() {
try {
//txtMsg.append("\n");
// obtain a list of from DB
String TABLE_NAME = "classicpoems__poet_contents";
String COLUMN_ID = "poet_id";
String _ID = "_id";
String COLUMN_NAME = "poet_name";
String COLUMN_CENTURY = "century_start";
String [] columns ={_ID,COLUMN_ID,COLUMN_NAME,COLUMN_CENTURY};
Cursor c = db.query(TABLE_NAME,columns,null, null, null, null, COLUMN_ID);
SimpleCursorAdapter adapter = new SimpleCursorAdapter(this, android.R.layout.simple_list_item_2, c,
new String[] {COLUMN_NAME,COLUMN_CENTURY}, new int[] {android.R.id.text1,android.R.id.text2}, 0);
ListView list = (ListView) findViewById(R.id.list_poet_name);
list.setAdapter(adapter);
} catch (Exception e) {
Toast.makeText(this, e.getMessage(), 1).show();
}
}
But here I have a problem..I want to send data of peot_id (Its deffrent from _id column in db) to next activity..Bt I mentioned that
with this code I can get whole row of selected item and I just want part of it(peot_id ) can you help me how to get just Peot_ID from selected
list item?
and I have another question..
As you see in my code I must refer to one spasial listview several times..each time I defined it by this code
enter code hereListView list = (ListView) findViewById(R.id.list_poet_name);
How can I define this listviwe one time and use it in several places in my code?sth like a public variable or sth like that
Thanks for your help.

As you see in my code I must refer to one spasial listview several
times..each time I defined it by this code
No. Just create one global ListView variable list and simply you can access to it from everywhere in your Activity. There is no need to declaring and initialising ListView again in OnItemClick() method.
I want to send data of peot_id (Its deffrent from _id column in db) to
next activity..Bt I mentioned that with this code I can get whole row
of selected item and I just want part of it(peot_id ) can you help me
how to get just Peot_ID from selected list item?
You are using Android's defined basic layout
android.R.layout.simple_list_item_2
I suggest you to create own XML file for row and then simply get whole View from ListView and from View you can get only ID.
Example:
listrow.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="10dp"
android:background="#drawable/addresses_list_selector"
>
<TextView
android:id="#+id/id_column"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>
<TextView
android:id="#+id/name_column"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="#id/id_column"
/>
<TextView
android:id="#+id/century_column"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="#id/name_column"
/>
</RelativeLayout>
Then an usage with CursorAdapter:
SimpleCursorAdapter adapter = new SimpleCursorAdapter(this, R.layout.listrow, c,
new String[] {COLUMN_ID, COLUMN_NAME, COLUMN_CENTURY},
new int[] {R.id.id_column, R.id.name_column, R.id.century_column}, 0);
And then for getting ID from row:
public void onItemClick(AdapterView<?> parent, View v, int position,
long id) {
TextView id = (TextView) v.findViewById(R.id.id_column);
if (id != null) {
String idString = id.getText().toString();
}
}
Note:
If you still want to use android's predefined layout, you need to pass into String[] from ID_COLUMN and then access to ID from row via row.findViewById(<id>);
String[] from = {ID_COLUMN, NAME_COLUMN};
int[] to = {android.R.id.text1, android.R.id.text2};
TextView id = v.findViewById(android.R.id.android.R.id.text1);
String idString = id.getText().toString();

You do query like this to get a Particular column record alone :
Cursor mCursor = mDb.query(true, DATABASE_TABLE, new String[] {KEY_ROWID,
KEY_NAME, KEY_DESIGNATION}, KEY_ROWID + "=" + yourPrimaryKey, null,
null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}

I personally prefer to use onListItemclick() method like that
//do not forget to override - very important
#Override
public void onListItemClick(ListView l, View v, int position, long id) {
//TODO what you what you have here the vars position - position of the selected item in list
// and also the id so you can easy trace what selection done the user
// you can play with this
}

how to make Android ListView refresh

I am currently unable to view newly inserted sqlite data from my ListView without restarting my whole application. Currently when a ListView item is selected, a new activity starts showing detailed information. once the detailed info is updated, edited, or the item is deleted the ListView is shown again but contain all original data unless app it closed and restarted. list view OnResume method is below. How do I refresh ListView when ever it is shown on screen. my attempts on adding .notifyDataSetChanged was unsuccessful. Not sure I implemented it correctly.
public List<String> populateList (){
List<String> webNameList = new ArrayList<String>();
dataStore openHelperClass = new dataStore (this);
SQLiteDatabase sqliteDatabase = openHelperClass.getReadableDatabase();
Cursor cursor = sqliteDatabase.query(dataStore.TABLE_NAME_INFOTABLE, null, null, null, null, null, dataStore.COLUMN_NAME_SITE, null);
startManagingCursor(cursor);
while (cursor.moveToNext()){
String sName = cursor.getString(cursor.getColumnIndex(dataStore.COLUMN_NAME_SITE));
String wUrl = cursor.getString(cursor.getColumnIndex(dataStore.COLUMN_NAME_ADDRESS));
String uName = cursor.getString(cursor.getColumnIndex(dataStore.COLUMN_NAME_USERNAME));
String pWord = cursor.getString(cursor.getColumnIndex(dataStore.COLUMN_NAME_PASSWORD));
String lNotes = cursor.getString(cursor.getColumnIndex(dataStore.COLUMN_NAME_NOTES));
LoginDetails lpDetails = new LoginDetails();
lpDetails.setsName(sName);
lpDetails.setwUrl(wUrl);
lpDetails.setuName(uName);
lpDetails.setpWord(pWord);
lpDetails.setlNotes(lNotes);
loginArrayList.add(lpDetails);
webNameList.add(sName);
}
sqliteDatabase.close();
return webNameList;
}
#Override
protected void onResume() {
super.onResume();
loginListAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, populateList());
loginList.setAdapter(loginListAdapter);
}
#Override
public void onItemClick(AdapterView<?> arg0 , View arg1, int arg2, long arg3) {
Toast.makeText(getApplicationContext(), "Selected ID :" + arg2, Toast.LENGTH_SHORT).show();
Intent updateDeleteLoginInfo = new Intent (this, UpdateDeleteLoginList.class);
LoginDetails clickedObject = loginArrayList.get(arg2);
Bundle loginBundle = new Bundle();
loginBundle.putString("clickedWebSite",clickedObject.getsName());
loginBundle.putString("clickedWebAddress",clickedObject.getwUrl());
loginBundle.putString("clickedUserName",clickedObject.getuName());
loginBundle.putString("clickedPassWord",clickedObject.getpWord());
loginBundle.putString("clickedNotes",clickedObject.getlNotes());
updateDeleteLoginInfo.putExtras(loginBundle);
startActivity(updateDeleteLoginInfo);

You're using startActivity. Why don't you use startActivityForResult instead? The answer to this question details how you would call the second Activity. Once it returns, you would have to use the notifyDataSetChanged() call.

startManagingCursor is deprecated.
Use CursorLoader instead.
It's very simple to use and updates your data in the ListView immediately when the data of the ContentProvider changes.
Here is a nice example:
http://www.vogella.com/articles/AndroidSQLite/article.html#todo_activities

You are only showing part of the app code, so I may be offbase here, but it appears you are using a Cursor to return a List and use the List to create an ArrayAdapter...
If you want the data to be 'fresh', why not use a CursorLoader with the LoaderManager? There are several benefits to the LoaderManager (like moving the query off of the UI thread), and the LoaderManager does a bit of the heavy lifting for you when it comes to monitoring the DB for changes.
There is a blog post that I've found quite helpful - http://www.androiddesignpatterns.com/2012/07/understanding-loadermanager.html