I got a question:
Values from ShopName if LocationCode is equal to a string called SKM will be inserted into an array called ShopName.
However, the array is empty, why?
DatabaseAccess.java
public class DatabaseAccess {
private SQLiteOpenHelper openHelper;
private SQLiteDatabase database;
private static DatabaseAccess instance;
/**
* Private constructor to aboid object creation from outside classes.
*
* #param context
*/
public DatabaseAccess(Context context) {
this.openHelper = new DatabaseOpenHelper(context);
}
/**
* Return a singleton instance of DatabaseAccess.
*
* #param context the Context
* #return the instance of DabaseAccess
*/
public static DatabaseAccess getInstance(DatabaseGrabber context) {
if (instance == null) {
instance = new DatabaseAccess(context);
}
return instance;
}
/**
* Open the database connection.
*/
public void open() {
this.database = openHelper.getWritableDatabase();
}
/**
* Close the database connection.
*/
public void close() {
if (database != null) {
this.database.close();
}
}
/**
* Read all quotes from the database.
*
* #return a List of quotes
*/
public List<String> getQuotes() {
String WhiteFarm = "SKM";
List<String> list = new ArrayList<>();
Cursor cursor = database.rawQuery("SELECT * FROM WhereToEat WHERE 'LocationCode' = " + "'" + WhiteFarm + "'", null);
cursor.moveToFirst();
if (cursor.moveToFirst()) {
do {
// do what you need with the cursor here
list.add(cursor.getString(0));
} while (cursor.moveToNext());
}
cursor.close();
return list;
}
}
DatabaseGrabber.java
public class DatabaseGrabber extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.selection_main);
final TextView Shop_name = (TextView)findViewById(R.id.ShopName);
DatabaseAccess databaseAccess = DatabaseAccess.getInstance(this);
databaseAccess.open();
final List<String> ShopName = databaseAccess.getQuotes();
databaseAccess.close();
Button StartDraw = (Button)findViewById(R.id.draw_start);
StartDraw.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (ShopName.size()>0) {
Collections.shuffle(ShopName);
String random = ShopName.get(0);
Shop_name.setText(random);
}
else{
Shop_name.setText("Nothing here!");
}
}
});
}
}
DatabaseOpenHelper.java
public class DatabaseOpenHelper extends SQLiteAssetHelper {
private static final String DATABASE_NAME = "WhereToEat";
private static final int DATABASE_VERSION = 1;
public DatabaseOpenHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
}
And this is the sql file
BEGIN TRANSACTION;
CREATE TABLE "WhereToEat" (
`ShopName` TEXT,
`Location` TEXT,
`LocationCode` TEXT,
`Photo` BLOB
);
INSERT INTO `WhereToEat` VALUES ('KFC','Shek Kip Mei','WhiteFarm',NULL);
INSERT INTO `WhereToEat` VALUES ('McDonalds','Lai Chi Kok','SKM',NULL);
INSERT INTO `WhereToEat` VALUES ('SomethingBig','Nam Cheong','SKM',NULL);
INSERT INTO `WhereToEat` VALUES ('Subway','Tsuen Wan','SKM',NULL);
COMMIT;
Thank you.
You have quotes around the column name in your WHERE clause. For each potential result row, you're checking whether 'LocationCode' = 'SKM', which is obviously always false.
Remove the quotes around the column name, and I expect you'll be fine.
While you're at it, clean up your code by using a placeholder (?) for the string value:
Cursor cursor = database.rawQuery(
"SELECT * FROM WhereToEat WHERE LocationCode = ?",
new String[]{WhiteFarm});
Related
I have a Fragment containing ListView. I'm adding some values to the database with a dialog and I want to update this ListView after dialog is dismissed. Also, when I change the tab, the ListView is not updated but when the application is turned on and off, the ListView is updated.
Fragment and Dialog classes are as follows:
Fragment:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View rootView = inflater.inflate(R.layout.fragment_teams, container, false);
listViewTeams = rootView.findViewById(R.id.listView_teams);
TeamDatabase teamDatabase = new TeamDatabase(getContext());
teamDatabase.open();
arrayListTeam = teamDatabase.getAllTeams();
teamDatabase.close();
int resID = R.layout.team_list_item;
teamListArrayAdapter = new TeamListArrayAdapter(getContext(), resID, arrayListTeam);
listViewTeams.setAdapter(teamListArrayAdapter);
return rootView;
}
Dialog onClick Method:
#Override
public void onClick(View view) {
int id = view.getId();
switch (id){
case R.id.button_alertDialogAddTeam_cancel:
this.dismiss();
break;
case R.id.button_alertDialogAddTeam_ok:
Team team = new Team();
team.setName(editTextTeamName.getText().toString());
team.setCode(editTextTeamCode.getText().toString());
TeamDatabase teamDatabase = new TeamDatabase(getContext());
teamDatabase.open();
if(teamDatabase.addNewTeam(team)) {
Toast.makeText(getContext(), team.getCode() + " - " +
team.getName() + " was added successfully", Toast.LENGTH_SHORT).show();
}
this.dismiss();
break;
}
}
TeamDatabase class:
public static final String TABLE_NAME = "team";
private static final String KEY_ID = "id";
private static final String KEY_NAME = "name";
private static final String KEY_CODE = "code";
private static final String KEY_EMBLEM = "emblem";
private Context context;
public static final String CREATE_TABLE = "CREATE TABLE "+
TABLE_NAME + " ("+
KEY_ID + " INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT UNIQUE, "+
KEY_NAME + " TEXT NOT NULL, "+
KEY_CODE + " TEXT NOT NULL, " +
KEY_EMBLEM + " TEXT);";
public TeamDatabase(Context context) {
super(context);
this.context = context;
}
public boolean addNewTeam(Team team){
ContentValues contentValues = new ContentValues();
contentValues.put(KEY_NAME, team.getName());
contentValues.put(KEY_CODE, team.getCode());
return db.insert(TABLE_NAME, null, contentValues) > 0;
}
public ArrayList<Team> getAllTeams()
{
ArrayList<Team> teams = new ArrayList<Team>();
Cursor cursor = db.query(TABLE_NAME, new String[]{KEY_ID,
KEY_NAME,
KEY_CODE}, null, null, null, null, null);
while(cursor.moveToNext()) {
Team team = new Team();
team.setId(cursor.getInt(cursor.getColumnIndex(KEY_ID)));
team.setName(cursor.getString(cursor.getColumnIndex(KEY_NAME)));
team.setCode(cursor.getString(cursor.getColumnIndex(KEY_CODE)));
teams.add(team);
}
return teams;
}
DatabaseHelper class:
private static final String DATABASE_NAME = "fixtureCreator.db";
private static final int DATABASE_VERSION = 1;
public SQLiteDatabase db;
public DatabaseHelper(Context context){
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
#Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
sqLiteDatabase.execSQL(TeamDatabase.CREATE_TABLE);
}
#Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int oldVersion, int newVersinon) {
Log.w("TaskDBAdapter", "Upgrading from version " +
oldVersion + " to " + newVersinon + ", which will destroy all old data");
sqLiteDatabase.execSQL("DROP TABLE IF EXISTS " + TeamDatabase.TABLE_NAME);
onCreate(sqLiteDatabase);
}
public DatabaseHelper open() throws SQLException {
try{
db = this.getWritableDatabase();
}catch (SQLException e){
db = this.getReadableDatabase();
}
return this;
}
public void close(){
db.close();
}
On clicking the item in your first Activity, start your second Activity with startActivityForResult()
And then in Second Activity, after dismissing the dialog,in onClick of that button call,
intent.putExtra("new data", "item text");
setResult(RESULT_OK, intent);
finish();
Now you come back to your first Activity and here you have to implement onActivityResult() callback.
You can extract data from that intent's extras and set that respective item in your array and call notifyDataSetChanged().
This is ideally how you should be doing it.
The problem can be solved using fetching the data after saving it each time you click on the Dialog and then call notifyDataSetChanged() on your adapter. However, there is more elegant way of achieving this kind of behaviour, which will solve both of your problems using content observer.
In case of having a content observer in your database table you need to declare a URI first which references your table.
public static final Uri DB_TABLE_TEAM_URI = Uri
.parse("sqlite://" + Constants.ApplicationPackage + "/" + DB_TABLE_TEAM);
// DB_TABLE_TEAM refers to the database table that you have for storing teams.
Now in your addNewTeam function you need to do the following.
public boolean addNewTeam(Team team) {
// .. Save the team in database
// Notify the observer about the change in the content
context.getContentResolver().notifyChange(DBConstants.DB_TABLE_TEAM_URI, null);
}
You need to call notifyChange() function whenever you add or update an entry in your team table.
Now in your Activity or Fragment you need to register your observer on your cursor having the team data fetched from your team table.
cursor = teamDatabase.getAllTeamsInCursor();
this.registerContentObserver(cursor, DBConstants.DB_TABLE_TEAM_URI);
Now populate your ListView using the cursor by passing it to your adapter of ListView. The list will be updated automatically once a new data has been inserted in your team table.
Update
Modify the addNewTeam function in your TeamDatabase class as follows.
public static final Uri DB_TABLE_TEAM_URI = Uri
.parse("sqlite://" + Constants.ApplicationPackage + "/" + DB_TABLE_TEAM);
public boolean addNewTeam(Team team){
ContentValues contentValues = new ContentValues();
contentValues.put(KEY_NAME, team.getName());
contentValues.put(KEY_CODE, team.getCode());
boolean success = db.insert(TABLE_NAME, null, contentValues) > 0;
context.getContentResolver().notifyChange(DBConstants.DB_TABLE_TEAM_URI, null);
return success;
}
To implement the functionalities with LoaderCallbacks you first need to implement the interface of LoaderCallbacks in your Fragment. So the declaration of your Fragment will look like.
public class TeamsFragment extends Fragment implements LoaderManager.LoaderCallbacks<Cursor> {
// .... Code
}
Now you need to override the functions that comes along with the interface of LoaderCallbacks.
#Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
return new SQLiteCursorLoader(getActivity()) {
#Override
public Cursor loadInBackground() {
// Initialize your database
TeamDatabase teamDatabase = new TeamDatabase(getActivity());
Cursor cursor = teamDatabase.getAllTeams();
if (cursor != null) {
// Register the content observer here
this.registerContentObserver(cursor, DBConstants.DB_TABLE_TEAM_URI);
}
return cursor;
}
};
}
#Override
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
// Set the cursor in your adapter. Handle null values in your setCursor function in your adapter. The cursor might return null when the table is empty.
teamAdapter.setCursor(cursor);
teamAdapter.notifyDataSetChanged();
}
#Override
public void onLoaderReset(Loader<Cursor> loader) {
}
Now in your onCreateView function in the Fragment, you need to initiate the loader to fetch data from the table.
getLoaderManager().initLoader(0, null, this).forceLoad();
And destroy the loader and un-register the receiver in the onDestroyView function.
#Override
public void onDestroyView() {
getLoaderManager().destroyLoader(0);
super.onDestroyView();
}
I was missing the SQLiteCursorLoader class to be added here.
package com.wooz.observer.databases;
import android.content.ContentResolver;
import android.content.Context;
import android.database.ContentObserver;
import android.database.Cursor;
import android.net.Uri;
import android.os.Handler;
import android.support.v4.content.AsyncTaskLoader;
import android.support.v4.content.Loader;
import java.io.FileDescriptor;
import java.io.PrintWriter;
import java.util.Arrays;
public abstract class SQLiteCursorLoader extends AsyncTaskLoader<Cursor> {
private final ForceLoadContentObserver mObserver;
private Uri mUri;
private String[] mProjection;
private String mSelection;
private String[] mSelectionArgs;
private String mSortOrder;
private Cursor mCursor;
/* Runs on a worker thread */
#Override
public abstract Cursor loadInBackground();
/**
* Registers an observer to get notifications from the content provider
* when the cursor needs to be refreshed.
*/
public void registerContentObserver(Cursor cursor, Uri observerUri) {
cursor.registerContentObserver(mObserver);
cursor.setNotificationUri(getContext().getContentResolver(), observerUri);
}
/* Runs on the UI thread */
#Override
public void deliverResult(Cursor cursor) {
try {
if (isReset()) {
// An async query came in while the loader is stopped
if (cursor != null) {
cursor.close();
}
return;
}
Cursor oldCursor = mCursor;
mCursor = cursor;
if (isStarted()) {
super.deliverResult(cursor);
}
if (oldCursor != null && oldCursor != cursor && !oldCursor.isClosed()) {
oldCursor.close();
}
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* Creates an empty unspecified CursorLoader. You must follow this with
* calls to {#link #setUri(Uri)}, {#link #setSelection(String)}, etc
* to specify the query to perform.
*/
public SQLiteCursorLoader(Context context) {
super(context);
mObserver = new ForceLoadContentObserver();
}
/**
* Creates a fully-specified CursorLoader. See
* {#link ContentResolver#query(Uri, String[], String, String[], String)
* ContentResolver.query()} for documentation on the meaning of the
* parameters. These will be passed as-is to that call.
*/
public SQLiteCursorLoader(Context context, Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
super(context);
mObserver = new ForceLoadContentObserver();
mUri = uri;
mProjection = projection;
mSelection = selection;
mSelectionArgs = selectionArgs;
mSortOrder = sortOrder;
}
/**
* Starts an asynchronous load of the contacts list data. When the result is ready the callbacks
* will be called on the UI thread. If a previous load has been completed and is still valid
* the result may be passed to the callbacks immediately.
* <p>
* Must be called from the UI thread
*/
#Override
protected void onStartLoading() {
if (mCursor != null) {
deliverResult(mCursor);
}
if (takeContentChanged() || mCursor == null) {
forceLoad();
}
}
/**
* Must be called from the UI thread
*/
#Override
protected void onStopLoading() {
// Attempt to cancel the current load task if possible.
cancelLoad();
}
#Override
public void onCanceled(Cursor cursor) {
if (cursor != null && !cursor.isClosed()) {
cursor.close();
}
}
#Override
protected void onReset() {
super.onReset();
// Ensure the loader is stopped
onStopLoading();
if (mCursor != null && !mCursor.isClosed()) {
mCursor.close();
}
mCursor = null;
}
public Uri getUri() {
return mUri;
}
public void setUri(Uri uri) {
mUri = uri;
}
public String[] getProjection() {
return mProjection;
}
public void setProjection(String[] projection) {
mProjection = projection;
}
public String getSelection() {
return mSelection;
}
public void setSelection(String selection) {
mSelection = selection;
}
public String[] getSelectionArgs() {
return mSelectionArgs;
}
public void setSelectionArgs(String[] selectionArgs) {
mSelectionArgs = selectionArgs;
}
public String getSortOrder() {
return mSortOrder;
}
public void setSortOrder(String sortOrder) {
mSortOrder = sortOrder;
}
#Override
public void dump(String prefix, FileDescriptor fd, PrintWriter writer, String[] args) {
super.dump(prefix, fd, writer, args);
writer.print(prefix);
writer.print("mUri=");
writer.println(mUri);
writer.print(prefix);
writer.print("mProjection=");
writer.println(Arrays.toString(mProjection));
writer.print(prefix);
writer.print("mSelection=");
writer.println(mSelection);
writer.print(prefix);
writer.print("mSelectionArgs=");
writer.println(Arrays.toString(mSelectionArgs));
writer.print(prefix);
writer.print("mSortOrder=");
writer.println(mSortOrder);
writer.print(prefix);
writer.print("mCursor=");
writer.println(mCursor);
//writer.print(prefix); writer.print("mContentChanged="); writer.println(mContentChanged);
}
private class CursorLoaderContentObserver extends ContentObserver {
public CursorLoaderContentObserver() {
super(new Handler());
}
#Override
public boolean deliverSelfNotifications() {
return true;
}
#Override
public void onChange(boolean selfChange) {
onContentChanged();
}
}
}
You should call notifyDataSetChanged just before dismissing the dialoge
teamListArrayAdapter.notifyDataSetChanged();
You should change you code something like this below
#Override
public void onClick(View view) {
int id = view.getId();
switch (id){
case R.id.button_alertDialogAddTeam_cancel:
this.dismiss();
break;
case R.id.button_alertDialogAddTeam_ok:
Team team = new Team();
team.setName(editTextTeamName.getText().toString());
team.setCode(editTextTeamCode.getText().toString());
TeamDatabase teamDatabase = new TeamDatabase(getContext());
teamDatabase.open();
if(teamDatabase.addNewTeam(team)) {
Toast.makeText(getContext(), team.getCode() + " - " +
team.getName() + " was added successfully", Toast.LENGTH_SHORT).show();
}
arrayListTeam = teamDatabase.getAllTeams();
teamListArrayAdapter.notifyDataSetChanged();
this.dismiss();
break;
}
}
Add this code in onCreateView:
teamListArrayAdapter.notifyDataSetChanged();
I am facing this strange problem that I searched alot, but no use so far.
The following code I am using to retrieve SQLite database using a DBHelper that extends from openhelper class.
public class DBHelper extends SQLiteOpenHelper {
public static final int DB_VERSION = 1;
public static final String DB_NAME = "cp.db";
public static final String DB_PATH = "/data/data/abdulla.com.test/databases/";
public static final String ID = "no";
public static final String NAME = "name";
public static final String FORMULA = "formula";
public static final String MW = "mw";
public static final String OMEGA = "omega";
public static final String TC = "tc";
public static final String PC = "pc";
SQLiteDatabase db;
Cursor cursor;
ArrayList<String> elementName;
public DBHelper(Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
#Override
public void onCreate(SQLiteDatabase db) {
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("drop table if exists elements");
this.onCreate(db);
}
public List<Element> getAllElements() {
List<Element> elementList = new ArrayList<Element>();
// Select All Query
Cursor cursor = null;
String selectQuery = "SELECT * FROM elements";
SQLiteDatabase db = this.getReadableDatabase();
cursor = db.rawQuery(selectQuery, null);
// looping through all rows and adding to list
if (cursor.moveToFirst()) {
do {
Element element = new Element();
element.setNo(Integer.parseInt(cursor.getString(0)));
element.setFormula(cursor.getString(1));
element.setName(cursor.getString(2));
// Adding contact to list
elementList.add(element);
} while (cursor.moveToNext());
}
// return contact list
return elementList;
}
}
This is capture from MainActivity class
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
DBHelper helper = new DBHelper(this);
List<Element> elementList = helper.getAllElements();
for(Element element : elementList){
String log = "no: "+element.getNo();
Log.d("No: ", log);
}
}
}
I am getting this error:
java.lang.RuntimeException: Unable to start activity
ComponentInfo{abdulla.com.test/abdulla.com.test.MainActivity}:
android.database.sqlite.SQLiteException: no such table: elements (code 1):
, while compiling: SELECT * FROM elements
I know that elements table is there
Any help?
Probably the issue is in your onUpgrade() method. If your database doesn't have version, application tries to upgrade it, and drops your table (db.execSQL("drop table if exists elements");).
Solution: set version to DB or change onUpgrade() method (delete DROP statement).
I have sqlite database I succeeded to get all data from it and I stored it in String data and then displayed it using another java class which just has Toast.
Now I am trying to send this data to another activity.
How to I achieve this?
NotesDbAdapter.java:
public class NotesDbAdapter {
public static final String KEY_TITLE = "title";
public static final String KEY_DATE = "date";
public static final String KEY_BODY = "body";
public static final String KEY_ROWID = "_id";
private static final String TAG = "NotesDbAdapter";
private DatabaseHelper mDbHelper;
private SQLiteDatabase mDb;
/**
* Database creation sql statement
*/
private static final String DATABASE_CREATE =
"create table notes (_id integer primary key autoincrement, "
+ "title text not null, body text not null, date text not null);";
private static final String DATABASE_NAME = "data";
private static final String DATABASE_TABLE = "notes";
private static final int DATABASE_VERSION = 2;
private final Context mCtx;
private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
#Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(DATABASE_CREATE);
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
+ newVersion + ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS notes");
onCreate(db);
}
}
/**
* Constructor - takes the context to allow the database to be
* opened/created
*
* #param ctx the Context within which to work
*/
public NotesDbAdapter(Context ctx) {
this.mCtx = ctx;
}
/**
* Open the notes database. If it cannot be opened, try to create a new
* instance of the database. If it cannot be created, throw an exception to
* signal the failure
*
* #return this (self reference, allowing this to be chained in an
* initialization call)
* #throws SQLException if the database could be neither opened or created
*/
public NotesDbAdapter open() throws SQLException {
mDbHelper = new DatabaseHelper(mCtx);
mDb = mDbHelper.getWritableDatabase();
return this;
}
public void close() {
mDbHelper.close();
}
/**
* Create a new note using the title and body provided. If the note is
* successfully created return the new rowId for that note, otherwise return
* a -1 to indicate failure.
*
* #param title the title of the note
* #param body the body of the note
* #return rowId or -1 if failed
*/
public long createNote(String title, String body, String date) {
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_TITLE, title);
initialValues.put(KEY_BODY, body);
initialValues.put(KEY_DATE, date);
return mDb.insert(DATABASE_TABLE, null, initialValues);
}
/**
* Delete the note with the given rowId
*
* #param rowId id of note to delete
* #return true if deleted, false otherwise
*/
public boolean deleteNote(long rowId) {
return mDb.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0;
}
/**
* Return a Cursor over the list of all notes in the database
*
* #return Cursor over all notes
*/
public Cursor fetchAllNotes() {
return mDb.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_TITLE,
KEY_BODY,KEY_DATE}, null, null, null, null, null);
}
/**
* Return a Cursor positioned at the note that matches the given rowId
*
* #param rowId id of note to retrieve
* #return Cursor positioned to matching note, if found
* #throws SQLException if note could not be found/retrieved
*/
public Cursor fetchNote(long rowId) throws SQLException {
Cursor mCursor =
mDb.query(true, DATABASE_TABLE, new String[] {KEY_ROWID,
KEY_TITLE, KEY_BODY,KEY_DATE}, KEY_ROWID + "=" + rowId, null,
null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
/**
* Update the note using the details provided. The note to be updated is
* specified using the rowId, and it is altered to use the title and body
* values passed in
*
* #param rowId id of note to update
* #param title value to set note title to
* #param body value to set note body to
* #return true if the note was successfully updated, false otherwise
*/
public boolean updateNote(long rowId, String title, String body,String date) {
ContentValues args = new ContentValues();
args.put(KEY_TITLE, title);
args.put(KEY_BODY, body);
//This lines is added for personal reason
args.put(KEY_DATE, date);
//One more parameter is added for data
return mDb.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0;
}
public String getALLData(){
mDb = mDbHelper.getWritableDatabase();
String[] columns={KEY_ROWID ,KEY_TITLE,KEY_BODY};
Cursor cursor = mDb.query(DATABASE_TABLE, columns, null, null, null, null, null);
StringBuffer buffer=new StringBuffer();
while (cursor.moveToNext()){
int cid=cursor.getInt(0);
String title=cursor.getString(1);
String body=cursor.getString(2);
buffer.append(cid+" "+title+" "+body+"\n");
}
return buffer.toString();
}}
The NoteEdit activity where I store data:
public class NoteEdit extends Activity {
public static int numTitle = 1;
public static String curDate = "";
public static String curText = "";
private EditText mTitleText;
private EditText mBodyText;
private TextView mDateText;
private Long mRowId;
private Cursor note;
private NotesDbAdapter mDbHelper;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mDbHelper = new NotesDbAdapter(this);
mDbHelper.open();
setContentView(R.layout.note_edit);
// getActionBar().setDisplayHomeAsUpEnabled(true);
setTitle(R.string.app_name);
mTitleText = (EditText) findViewById(R.id.title);
mBodyText = (EditText) findViewById(R.id.body);
mDateText = (TextView) findViewById(R.id.notelist_date);
long msTime = System.currentTimeMillis();
Date curDateTime = new Date(msTime);
SimpleDateFormat formatter = new SimpleDateFormat("d'/'M'/'y");
curDate = formatter.format(curDateTime);
mDateText.setText(""+curDate);
mRowId = (savedInstanceState == null) ? null :
(Long) savedInstanceState.getSerializable(NotesDbAdapter.KEY_ROWID);
if (mRowId == null) {
Bundle extras = getIntent().getExtras();
mRowId = extras != null ? extras.getLong(NotesDbAdapter.KEY_ROWID)
: null;
}
populateFields();
}
public static class LineEditText extends EditText{
// we need this constructor for LayoutInflater
public LineEditText(Context context, AttributeSet attrs) {
super(context, attrs);
mRect = new Rect();
mPaint = new Paint();
mPaint.setStyle(Paint.Style.FILL_AND_STROKE);
mPaint.setColor(Color.BLUE);
}
private Rect mRect;
private Paint mPaint;
#Override
protected void onDraw(Canvas canvas) {
int height = getHeight();
int line_height = getLineHeight();
int count = height / line_height;
if (getLineCount() > count)
count = getLineCount();
Rect r = mRect;
Paint paint = mPaint;
int baseline = getLineBounds(0, r);
for (int i = 0; i < count; i++) {
canvas.drawLine(r.left, baseline + 1, r.right, baseline + 1, paint);
baseline += getLineHeight();
super.onDraw(canvas);
}
}
}
#Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
saveState();
outState.putSerializable(NotesDbAdapter.KEY_ROWID, mRowId);
}
#Override
protected void onPause() {
super.onPause();
saveState();
}
#Override
protected void onResume() {
super.onResume();
populateFields();
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.noteedit_menu, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.menu_about:
/* Here is the introduce about myself */
AlertDialog.Builder dialog = new AlertDialog.Builder(NoteEdit.this);
dialog.setTitle("About");
dialog.setMessage("This project "
);
dialog.setPositiveButton("OK", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
dialog.show();
return true;
case R.id.menu_delete:
if(note != null){
note.close();
note = null;
}
if(mRowId != null){
mDbHelper.deleteNote(mRowId);
}
finish();
return true;
//speech button
case R.id.menu_speech:
//saveState();
//finish();
return true;
case R.id.menu_save:
saveState();
finish();
return true;
/* case android.R.id.home:
finish(); */
default:
return super.onOptionsItemSelected(item);
}
}
private void saveState() {
String title = mTitleText.getText().toString();
String body = mBodyText.getText().toString();
if(mRowId == null){
long id = mDbHelper.createNote(title, body, curDate);
if(id > 0){
mRowId = id;
}else{
Log.e("saveState","failed to create note");
}
}else{
if(!mDbHelper.updateNote(mRowId, title, body, curDate)){
Log.e("saveState","failed to update note");
}
}
}
private void populateFields() {
if (mRowId != null) {
note = mDbHelper.fetchNote(mRowId);
startManagingCursor(note);
mTitleText.setText(note.getString(
note.getColumnIndexOrThrow(NotesDbAdapter.KEY_TITLE)));
mBodyText.setText(note.getString(
note.getColumnIndexOrThrow(NotesDbAdapter.KEY_BODY)));
curText = note.getString(
note.getColumnIndexOrThrow(NotesDbAdapter.KEY_BODY));
}
}
public void viewDetails(View view){
String data= mDbHelper.getALLData();
Message.message(this,data);
}
}
Assuming you correctly received data from the database, you can send them to another activity of your app with various ways. The most simple of them being extras. Click the link and navigate to the paragraph that it titled "Extras" to see how you can use them.
You can pass your values like
Intent intent=new Intent(getApplicationContext(), SecondActivity.class);
intent.putExtra("key1", "your value1 here");
intent.putExtra("key2", "your value2 here");
startActivity(intent);
And recive your value like
String your_value1=getIntent().getStringExtra("key1");
String your_value2=getIntent().getStringExtra("key2");
you can pass String,integer,float,...
You can even pass a complete object too.
I want to set the background color of a listview row from an array in the sqldatabase.
The KEY_COLOR contains the list of colors.
Help would be appreciated!
Here are the main activity methods:
MainActivity:
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.notes_list);
mDbHelper = new NotesDbAdapter(this);
mDbHelper.open();
fillData();
registerForContextMenu(getListView());
}
private void fillData() {
// Get all of the rows from the database and create the item list
mNotesCursor = mDbHelper.fetchAllNotes();
startManagingCursor(mNotesCursor);
// Create an array to specify the fields we want to display in the list (only TITLE)
String[] from = new String[]{NotesDbAdapter.KEY_TITLE, NotesDbAdapter.KEY_BODY};
// and an array of the fields we want to bind those fields to (in this case just text1)
int[] to = new int[]{R.id.text1, R.id.date};
// Now create a simple cursor adapter and set it to display
SimpleCursorAdapter notes =
new SimpleCursorAdapter(this, R.layout.notes_row, mNotesCursor, from, to);
setListAdapter(notes);
}
And here is the Database Adapter:
public class NotesDbAdapter {
public static final String KEY_TITLE = "title";
public static final String KEY_BODY = "body";
public static final String KEY_ROWID = "_id";
public static final String KEY_COLOR = "color";
private static final String TAG = "NotesDbAdapter";
private DatabaseHelper mDbHelper;
private SQLiteDatabase mDb;
/**
* Database creation sql statement
*/
private static final String DATABASE_CREATE =
"create table notes (_id integer primary key autoincrement, "
+ "title text not null, body text not null, color text not null);";
private static final String DATABASE_NAME = "data";
private static final String DATABASE_TABLE = "notes";
private static final int DATABASE_VERSION = 3;
private final Context mCtx;
private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
#Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(DATABASE_CREATE);
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
+ newVersion + ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS notes");
onCreate(db);
}
}
/**
* Constructor - takes the context to allow the database to be
* opened/created
*
* #param ctx the Context within which to work
*/
public NotesDbAdapter(Context ctx) {
this.mCtx = ctx;
}
/**
* Open the notes database. If it cannot be opened, try to create a new
* instance of the database. If it cannot be created, throw an exception to
* signal the failure
*
* #return this (self reference, allowing this to be chained in an
* initialization call)
* #throws SQLException if the database could be neither opened or created
*/
public NotesDbAdapter open() throws SQLException {
mDbHelper = new DatabaseHelper(mCtx);
mDb = mDbHelper.getWritableDatabase();
return this;
}
public void close() {
mDbHelper.close();
}
/**
* Create a new note using the title and body provided. If the note is
* successfully created return the new rowId for that note, otherwise return
* a -1 to indicate failure.
*
* #param title the title of the note
* #param body the body of the note
* #return rowId or -1 if failed
*/
public long createNote(String title, String body, String color) {
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_TITLE, title);
initialValues.put(KEY_BODY, body);
initialValues.put(KEY_COLOR, color);
return mDb.insert(DATABASE_TABLE, null, initialValues);
}
/**
* Delete the note with the given rowId
*
* #param rowId id of note to delete
* #return true if deleted, false otherwise
*/
public boolean deleteNote(long rowId) {
return mDb.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0;
}
/**
* Return a Cursor over the list of all notes in the database
*
* #return Cursor over all notes
*/
public Cursor fetchAllNotes() {
return mDb.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_TITLE,
KEY_BODY, KEY_COLOR}, null, null, null, null, null);
}
/**
* Return a Cursor positioned at the note that matches the given rowId
*
* #param rowId id of note to retrieve
* #return Cursor positioned to matching note, if found
* #throws SQLException if note could not be found/retrieved
*/
public Cursor fetchNote(long rowId) throws SQLException {
Cursor mCursor =
mDb.query(true, DATABASE_TABLE, new String[] {KEY_ROWID,
KEY_TITLE, KEY_BODY, KEY_COLOR}, KEY_ROWID + "=" + rowId, null,
null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
/**
* Update the note using the details provided. The note to be updated is
* specified using the rowId, and it is altered to use the title and body
* values passed in
*
* #param rowId id of note to update
* #param title value to set note title to
* #param body value to set note body to
* #return true if the note was successfully updated, false otherwise
*/
public boolean updateNote(long rowId, String title, String body, String color) {
ContentValues args = new ContentValues();
args.put(KEY_TITLE, title);
args.put(KEY_BODY, body);
args.put(KEY_COLOR, color);
return mDb.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0;
}
}`
You can't use a SimpleCursorAdapter for this. Write a custom adapter and in the getView function set the color of the view for the row via setBackground. Or you can probably do this by inheriting from SimpleCursorAdapter, then overriding getView to look like this
view ret = super.getView();
ret.setBackground(color_you_want);
return ret;
I'm new to Java and just tried to make a database. I managed to make a DB and all but when I want to read the values it seems to get an error.
This is my code for my settings activity (which asks for setting values and add them in the DB on a specific ID)
public class Settings extends Activity{
Button Save;
static Switch SwitchCalculations;
public static String bool;
public static List<Integer> list_id = new ArrayList<Integer>();
public static List<String> list_idname = new ArrayList<String>();
public static List<String> list_kind = new ArrayList<String>();
public static List<String> list_value = new ArrayList<String>();
static Integer[] arr_id;
static String[] arr_idname;
static String[] arr_kind;
static String[] arr_value;
public static final String TAG = "Settings";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.settings);
Save = (Button) findViewById(R.id.btnSave);
SwitchCalculations = (Switch) findViewById(R.id.switchCalcOnOff);
readData();
Save.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
writeData();
//Toast.makeText(this, "Data has been saved.", Toast.LENGTH_SHORT).show();
readData();
Save.setText("Opgeslagen");
}
});
}
public void writeData() {
int id = 1;
String idname = "switchCalcOnOff";
String kind = "switch";
boolean val = SwitchCalculations.isChecked();
String value = new Boolean(val).toString();
dbHelper_Settings dbh = new dbHelper_Settings(this);
SQLiteDatabase db = dbh.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put(dbh.C_ID, id);
cv.put(dbh.C_IDNAME, idname);
cv.put(dbh.C_KIND, kind);
cv.put(dbh.C_VALUE, value);
if (dbh.C_ID.isEmpty() == true) {
db.insert(dbh.TABLE, null, cv);
Log.d(TAG, "Insert: Data has been saved.");
} else if (dbh.C_ID.isEmpty() == false) {
db.update(dbh.TABLE, cv, "n_id='1'", null);
Log.d(TAG, "Update: Data has been saved.");
} else {
Log.d(TAG, "gefaald");
}
db.close();
}
public void readData() {
dbHelper_Settings dbh = new dbHelper_Settings(this);
SQLiteDatabase db = dbh.getWritableDatabase();
List<String> list_value = new ArrayList<String>();
String[] arr_value;
list_value.clear();
Cursor cursor = db.rawQuery("SELECT " + dbh.C_VALUE + " FROM " + dbh.TABLE + ";", null);
if (cursor.moveToFirst()) {
do {
list_value.add(cursor.getString(0));
} while (cursor.moveToNext());
}
if (cursor != null && !cursor.isClosed()){
cursor.close();
}
db.close();
arr_value = new String[list_value.size()];
for (int i = 0; i < list_value.size(); i++){
arr_value[i] = list_value.get(i);
}
}
}
Then I have my dbHelper activity see below:
package com.amd.nutrixilium;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class dbHelper_Settings extends SQLiteOpenHelper{
private static final String TAG="dbHelper_Settings";
public static final String DB_NAME = "settings.db";
public static final int DB_VERSION = 10;
public final String TABLE = "settings";
public final String C_ID = "n_id"; // Special for id
public final String C_IDNAME = "n_idname";
public final String C_KIND = "n_kind";
public final String C_VALUE = "n_value";
Context context;
public dbHelper_Settings(Context context) {
super(context, DB_NAME, null, DB_VERSION);
this.context = context;
}
// oncreate wordt maar 1malig uitgevoerd per user voor aanmaken van database
#Override
public void onCreate(SQLiteDatabase db) {
String sql = String.format("create table %s (%s int primary key, %s TEXT, %s TEXT, %s TEXT)", TABLE, C_ID, C_IDNAME, C_KIND, C_VALUE);
Log.d(TAG, "onCreate sql: " + sql);
db.execSQL(sql);
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("drop table if exists " + TABLE); // wist een oudere database versie
Log.d(TAG, "onUpgrate dropped table " + TABLE);
this.onCreate(db);
}
}
And the weird thing is I don't get any error messages here.
But I used Log.d(TAG, text) to check where the script is being skipped and that is at cursor.moveToFirst().
So can anyone help me with this problem?
Here, contrary to what you seem to expect, you actually check that a text constant is not empty:
if (dbh.C_ID.isEmpty() == true) {
It isn't : it always contains "n_id"
I think your intent was to find a record with that id and, depending on the result, either insert or update.
You should do just that: attempt a select via the helper, then insert or update as in the code above.
Edit:
Add to your helper something like this:
public boolean someRowsExist(SQLiteDatabase db) {
Cursor cursor = db.rawQuery("select EXISTS ( select 1 from " + TABLE + " )", new String[] {});
cursor.moveToFirst();
boolean exists = (cursor.getInt(0) == 1);
cursor.close();
return exists;
}
And use it to check if you have any rows in the DB:
if (dbh.someRowsExist(db)) { // instead of (dbh.C_ID.isEmpty() == true) {
Looks like you're having trouble debugging your query. Android provides a handy method DatabaseUtils.dumpCursorToString() that formats the entire Cursor into a String. You can then output the dump to LogCat and see if any rows were actually skipped.