Hi I am new to android and I want to know how I can add buttons to my app programmatically . Actually the scenario is like this: In my app, I am having several default categories(given as buttons) to save data. I must provide an option add categories. When I click on the add categories button I must get an option to specify the category name and the sub category name(which i can do). But the thing is that I must get a new button with the entered name and it should not get deleted when i leave the application. Any help is highly appreciated.
To create database: refer How do I create a database in android?
Then you need to use DatabaseHelper class to insert,update or delete data on your database.
refer http://developer.android.com/reference/android/database/sqlite/SQLiteOpenHelper.html
Now you must be able to manage your data using DatabaseHelper class's object in your activity.
1.DatabaseCreator.java
public class DatabaseCreator extends SQLiteOpenHelper{
private static final String DB_NAME="database_name";
private static final int DB_VER=1;
private static final String TABLE_NAME="create table table_name(_id integer primary key autoincrement,field1 text not null,field2 text not null)";
public DatabaseCreator(Context context)
{
super(context,DB_NAME, null, DB_VER);
}
#Override
public void onCreate(SQLiteDatabase database)
{
database.execSQL(TABLE_NAME);
}
#Override
public void onUpgrade(SQLiteDatabase database, int arg1, int arg2) {
database.execSQL("DROP TABLE IF EXISTS table_name");
onCreate(database);
}
}
2.DatabaseHelper.java
public class DatabaseHelper
{
public static final String TABLENAME_DB="table_name";
public static final String KEY_ID="_id";
public static final String KEY_FIELD1="field1";
public static final String KEY_FIELD2="field2";
Context context;
SQLiteDatabase sqdb;
DatabaseCreator dbcreator;
public DatabaseHelper(Context context)
{
this.context=context;
}
public DatabaseHelper open() throws SQLException
{
dbcreator=new DatabaseCreator(context);
sqdb=dbcreator.getWritableDatabase();
return this;
}
public void close()
{
dbcreator.close();
}
public long addItem(String field1,String field2)
{
ContentValues values=new ContentValues();
values.put(KEY_FIELD1,field1);
values.put(KEY_FIELD2,field2);
return sqdb.insert(TABLENAME_DB,null,values);
}
public long deletItem(long _id)
{
return sqdb.delete(TABLENAME_DB, "_id="+_id,null);
}
}
Use this in your activity like:
DatabaseHelper db_helper=new DatabaseHelper(getApplicationContext());
db_helper.open();
db_helper.addItem("field1_value","field2_value");
db_helper.close();
Related
In my app, I have a database with a table that contains several user made entries. Here's a simplified version of my SQLite database helper class:
public class DatabaseHelper extends SQLiteOpenHelper {
public static final String DATABASE_NAME = "data.db";
public static final String TABLE_NAME = "log";
public static final String COL_1 = "ID"; //autoincrement in oncreate
...
public static final String COL_12 = "NUMBER"; //set through getCount()
public DatabaseHelper(Context context) {
...
}
#Override
public void onCreate(SQLiteDatabase db) {
...
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
...
}
public long getCount() {
...
}
public boolean insertData(...) {
...
}
public void update(long id, String param) {
...
}
public Cursor getAllData() {
...
}
//for when an entry is deleted and thus COL_12 numbering is not fixed
public void consolidate() {
SQLiteDatabase db = this.getWritableDatabase();
db.execSQL("ALTER TABLE log ORDER BY NUMBER ASC");
}
}
However, whenever I call myDb.consolidate(), my app crashes. From what I've read from other posts, this should work, but it only throws error code 1: missing database. Anyone know why? Any help is appreciated.
I'm new to android. Here's one of my OnClickListeners. The thing is I don't know how to make it save when clicking the button. When I call createEventT(Event event), it says "non-static method cannot be referenced from a static context". Sometimes there's no error message, but the app crashes when clicking this button. Any ideas? Thanks.
OnClickListener:
OnClickListener doneT = new OnClickListener(){
#Override
public void onClick(View v) {
event.setTitle(inputToday.toString());
event.setYY(bearsCalendar.get(Calendar.YEAR));
event.setMM(bearsCalendar.get(Calendar.MONTH));
event.setDD(bearsCalendar.get(Calendar.DAY_OF_MONTH));
dateToday.setText(EventDBAdapter.createEventT(event));
}
};
And the event class:
public class Event {
int YY,MM,DD;
private String title;
public void setYY(int YY){this.YY=YY;}
public void setMM(int MM){this.MM=MM;}
public void setDD(int DD){this.DD=DD;}
public void setTitle(String title){this.title=title;};
public int getYY(){return YY;}
public int getMM(){return MM;}
public int getDD(){return DD;}
public String getTitle(){return title;}
}
public class EventDBAdapter{
private final Context mCtx;
static final String dbName="BearDatabase";
static final String eventTable="Events";
static final int dbVersion=1;
static final String colID="EventId";
static final String colTitle="Title";
static final String colDetails="Details";
static final String colYear="YY";
static final String colMonth="MM";
static final String colDay="DD";
static final String colHour="HH";
static final String colMinute="TT";
public DatabaseHelper mDbHelper;
public SQLiteDatabase mDb;
public EventDBAdapter(Context context){
mCtx=context;
}
private static class DatabaseHelper extends SQLiteOpenHelper{
DatabaseHelper(Context context){
super(context,dbName,null,dbVersion);
}
#Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE "+eventTable+" ("+colID+" INTEGER PRIMARY KEY , "
+colTitle+" TEXT NOT NULL , "+colDetails+" TEXT , "
+colYear+" INTEGER , "+colMonth+" INTEGER , "+colDay+" INTEGER , "
+colHour+" INTEGER , "+colMinute+" INTEGER );");
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + eventTable);
onCreate(db);
}
}
public EventDBAdapter open() throws SQLException{
mDbHelper = new DatabaseHelper(mCtx);
mDb = mDbHelper.getWritableDatabase();
return this;
}
public void close() {
mDbHelper.close();
}
public void upgrade(){
mDbHelper = new DatabaseHelper(mCtx);
mDb = mDbHelper.getWritableDatabase();
mDbHelper.onUpgrade(mDb, 1, 0);
}
public long createEventT(Event event){
ContentValues values = new ContentValues();
values.put(colTitle,event.getTitle());
values.put(colYear,event.getYY());
values.put(colMonth, event.getMM());
values.put(colDay, event.getDD());
return mDb.insert(eventTable,null,values);
}
public long createEventI(Event event){
ContentValues values = new ContentValues();
values.put(colTitle,event.getTitle());
return mDb.insert(eventTable,null,values);
}
}
Update:
Any problems in the database? After I made the changes, the whole thing crush.
change below to
dateToday.setText(EventDBAdapter.createEventT(event));
with below and it will work.
dateToday.setText(String.valueOf(EventDBAdapter.createEventT(event)));
I hope you are initializing event object before using it in onClick. if not, then initialize it like event = new Event(); before
event.setTitle(inputToday.toString());
Unless EventDBAdapter in your question is an instance of the EventDBAdapter class, then you are attempting to use a non-static method (public long createEventT()) in a static way (by accessing it through the class name).
To access it, you first need to create an instance of EventDBAdapter. One way to achieve this would probably be (assuming you are calling this method from inside an Activity):
long date = new EventDBAdapter(this).createEventT(event);
dateToday.setText(String.valueOf(date));
There are more answers on this topic here.
I am having a class named GameDb and it's extending SQLiteOpenHelper. I don't know why, but onCreate it's not called, the table is not created !
Having a singelton for all my activities and fragments:
public MyApp extends Application
{
// .... Code
private GameDb gameDb;
public GameDb getGameDb()
{
if (gameDb == null)
gameDb = new GameDb(this);
return this.gameDb;
}
}
Getting all games from database, calling from an activity
public class MyActivity extends FragmentActivity
{
#Override
protected void onCreate(Bundle bundle)
{
// Code....
// Get all games
ArrayList<Game> allGames = getMyApp().getGameDb().getAllGames();
}
}
Class which contains all necessary methods for querying the database (writing and reading). This methods are not written below because it's not necessary.
public class GameDb
{
private SQLiteDatabase db;
private GameDbHelper dbHelper;
public GameDb(Context context)
{
this.dbHelper = new GameDbHelper(context);
this.db = dbHelper.getWritableDatabase();
}
public ArrayList<Games> getAllGames()
{
// return db.query(....);
}
public void insertNewGame(int id, String name)
{
// db.query(....);
}
// Static inner class which extends SQLiteOpenHelper
private static class GameDbHelper extends SQLiteOpenHelper
{
public GameDbHelper(Context context)
{
super(context, "DB_NAME", null, 1);
}
// On create not called !
#Override
public void onCreate(SQLiteDatabase db)
{
db.execSQL("CREATE TABLE my_table(_id INTEGER AUTOINCREMENT, date TEXT);");
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
dropTable(db);
onCreate(db);
}
public void dropTable(SQLiteDatabase db)
{
db.execSQL("DROP TABLE IF EXISTS my_table");
}
}
}
When I'm trying to get all games, or add a new game I'm getting a FATAL EXCEPTION, (1) no such table: my_table
You may have a old database present on your device and database doesn't always get deleted when you reinstall the app using IDE. Thus you must uninstall the app manually and the reinstall your app using IDE.
I don't believe onCreate() gets implicitly called when you instantiate your database object. You need to explicitly call your Activity's openOrCreateDatabase() method.
First let you know I am new in Android.
Trying to create multiple classes to handle database table operations. Created a database helper as follow:
public class WSDatabaseHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "wsemp";
private static final int DATABASE_VERSION = 5;
public WSDatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
#Override
public void onCreate(SQLiteDatabase database) {
.............
}
#Override
public void onUpgrade(SQLiteDatabase database, int oldVersion, int newVersion) {
................
}
}
Created a class to handle database table operation:
public class CustomerBean {
private WSDatabaseHelper database;
#Override
public boolean onCreate() {
database = new WSDatabaseHelper(getContext());
return false;
}
public boolean insertObject(valObj) {
SQLiteDatabase db = database.getWritableDatabase();
db.insert(.......);
}
}
But now I am not sure how I can call this insertObject function from my activity or session file. I tried by CustomerBean.isnertObject(obj) but it's asking to change the method to static.
There are two ways to call method in this situation
Create the object of the class and call method
// Create object
CustomerBean customerBean = new CustomerBean();
// call the method
customerBean.insertObject(<insert object here>);
Make the method static and call it from class name
// In CustomerBean class
public static boolean insertObject(valObj) {
SQLiteDatabase db = database.getWritableDatabase();
db.insert(.......);
}
//In WSDatabaseHelper class
CustomerBean.insertObject(<object name here>);
On more thing to correct here is that in CustomerBean class you have written
#Override
public boolean onCreate() {
database = new WSDatabaseHelper(getContext());
return false;
}
Which is not correct. onCreate() method of Activity class of Android and
you can put #Override Annotation for this method only if your class is extending Activity class
Hope this will help you
Add the static modifier to your method. Then you should be able to access it between classes.
following is the code that i used to alter my table but my app is crashing.
I have create this dbupdateadapter class separately. the records are being added, but the column is not added to the same table
public class dbupdateadapter {
public static final String TABLE_MEMBERID="memberid";
private static final String DATABASE_NAME="myfemmefab.db";
private static final String TABLE_NAME="registeration";
private static final int DATABASE_VERSION=2;
private static final String DATABASE_UPDATE="ALTER TABLE registeration ADD COLUMN(memberid TEXT);";
private static Context context1;
private dbhelper1 helper1;
private SQLiteDatabase sdb1;
public dbupdateadapter(Context con){
this.context1=con;
helper1=new dbhelper1(context1);
}
public class dbhelper1 extends SQLiteOpenHelper{
public dbhelper1(Context context){
super(context,DATABASE_NAME,null,DATABASE_VERSION);
}
#Override
public void onCreate(SQLiteDatabase sdb1){
sdb1.execSQL(DATABASE_UPDATE);
}
#Override
public void onUpgrade(SQLiteDatabase sdb1,int oldver,int newver){
//android.util.Log.w("constants", "upgrading database will destroy the old data");
if(newver>oldver){
sdb1.execSQL(DATABASE_UPDATE);
}
//onCreate(sdb1);
}
}
public dbupdateadapter open() throws SQLException{
sdb1=helper1.getWritableDatabase();
return this;
}
void insertcoldata (String memberid){
ContentValues cv1=new ContentValues();
cv1.put(TABLE_MEMBERID, memberid);
sdb1.insert(TABLE_NAME, null, cv1);
}
public void close(){
helper1.close();
}
}
You should know that in
public void onCreate(SQLiteDatabase db ){ ... }
you should create your tables and populate them with some initial values and you didn't create table in your snippet of code.
for upgrating your tables you should use
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { ... }
Exactly from docs:
Called when the database needs to be upgraded. The implementation
should use this method to drop tables, add tables, or do anything else
it needs to upgrade to the new schema version.
Also have look at
SQL As Understood By
SQLite
Example of how to implement ALTER
TABLE
Use "ALTER TABLE registeration ADD memberid TEXT;"; or "ALTER TABLE registeration ADD COLUMN memberid TEXT;"; You have an error in syntax.
Where are you creating yout table? You are executing DATABASE_UPDATE in your onCreate().