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Insert data in sqlitedatabase using AndroidStudio

I am trying to insert data in the table MyProduct but every time i run the program it shows "null pointer exception" in db.insertData() in MainActivity and method insertData() in MyHelper class. Can anyone please tell me whats going wrong?? Thank You
MainActivity
public class MainActivity extends Activity {
MyHelper helper;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
helper=new MyHelper(this);
SQLiteDatabase sqLiteDatabase=helper.getWritableDatabase();
// helper.onCreate(sqLiteDatabase);
helper.insertData();
}
}
MyHelper.class
public class MyHelper extends SQLiteOpenHelper {
static final String DATABASE_NAME="MyDatabase";
static final int DATABASE_VERSION=1;
static final String TABLE_NAME="MyCatalog";
static final String UID="ID";
static final String UTITLE="TITLE";
static final String UPRICE="PRICE";
static final String UDESCP="DESCP";
static final String CREATE_TABLE="CREATE TABLE"+TABLE_NAME+"("+UID+"VARCHAR(25) PRIMARY KEY,"+UTITLE+ " VARCHAR(255),"+UPRICE+" VARCHAR(255),"+UDESCP+" VARCHAR(255));";
private static final String DROP_TABLE="DROP TABLE" +TABLE_NAME+"IF EXISTS";
private Context context;
public MyHelper(Context context)
{
super(context,DATABASE_NAME,null,DATABASE_VERSION);
this.context=context;
Message.message(context,"Constructor called");
}
public void onCreate(SQLiteDatabase db)
{
Message.message(context,"on create");
db.execSQL(CREATE_TABLE);
Message.message(context,"table created");
}
public void onUpgrade(SQLiteDatabase db,int oldVersion,int newVersion)
{
Message.message(context,"upgrade called");
db.execSQL(DROP_TABLE);
onCreate(db);
}
ContentValues contentValues;
public SQLiteDatabase db;
public void insertData()
{
contentValues.put(UID,"W");
contentValues.put(UTITLE,"w");
contentValues.put(UPRICE,"10");
contentValues.put(UDESCP, "abc");
db.insert(TABLE_NAME, null, contentValues);
}
}

You haven't initialized your db or contentValues objects. At the start of your insertData method, try putting the following:
db = getWriteableDatabase();
contentValues = new ContentValues();

SQLite database problems

I have veritabani.java and i create database in this class. Then i create object in mainactivity.java. But when i run app. the program dont move database.java so i cant create database how i can solve this problem.
veritabani.java
public class veritabani extends SQLiteOpenHelper {
private static final String VERİTABANİ_ADİ="kayit";
public veritabani(Context c)
{
super(c,VERİTABANİ_ADİ,null,2);
}
#Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE kayit(ilacadi TEXT);");
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXIST kayit");
onCreate(db);
}
}
mainactivity.java
public class MainActivity extends Activity {
private veritabani v1;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.home);
v1=new veritabani(this);
}
v1=new veritabani(this) doesnt work.

Try this code
public class DBAdapter
{
private static final String DATABASE_NAME = "GSDATA.db";
private static final int DATABASE_VERSION = 2;
private static final String CREATE_COVERPHOTO_TABLE = "CREATE TABLE IF NOT EXISTS COVERPHOTO (path Text,date DATE);";
private final Context context;
public String group;
private DatabaseHelper DBHelper;
private static SQLiteDatabase db;
public DBAdapter(Context ctx)
{
this.context = ctx;
DBHelper = new DatabaseHelper(context);
}
private class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
#Override
public void onCreate(SQLiteDatabase db)
{
db.execSQL(CREATE_COVERPHOTO_TABLE);
System.out.println("The Database is Created Here :");
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// db.execSQL("DROP TABLE IF EXISTS calSimpleNote");
onCreate(db);
}
} // database helper class complete
// ---opens the database---
public DBAdapter open() throws SQLException {
db = DBHelper.getWritableDatabase();
return this;
}
// ---closes the database---
public void close() {
DBHelper.close();
db.close();
}
// and write below line in main activity
DBAdapter adapter = new DBAdapter(MainActivity.this);

I'm not sure what you mean by "the program dont move database.java" but i had issues with databases using SQLiteOpenHelper.
Actually, SQLiteOpenHelper calls " public void onCreate(SQLiteDatabase db)" only once, so if you change your tables between 2 launch, it won't be updated.
To solve this you have to manually delete the database by going into parameters / applications / [your_app] / erase data (or something like this) and try again.

db.insert only stores auto incremented id in database

db.insert function inserts only an auto incremented ID in the table and nothing else though I get values from activity edit texts. Rest of the cells of table row remain empty
Here is my code:
public class SHelper extends SQLiteOpenHelper {
static final String dbName = "School";
static final String studentTable = "Student";
static final String colName = "Name";
static final String colPassword = "Password";
public static final int dbVersion=1;
public SHelper(Context context)
{
super(context, dbName, null, dbVersion);
}
#Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE "+studentTable+"("+colID+" INTEGER PRIMARY KEY, "+colName+" TEXT,"+colPassword+" TEXT);");
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + studentTable);
onCreate(db);
}
public void add(StudentData studentdata)
{
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(colName, StudentData.getName());
values.put(colPassword, StudentData.getPassword());
db.insert(studentTable, null, values);
db.close();
}
}
public class StudentData {
private static String name;
private static String password;
public StudentData() {
super();
}
public StudentData(String name,String password) {
super();
StudentData.name = name;
StudentData.password = password;
}
public static String getName() {
return name;
}
public void setName(String name) {
StudentData.name = name;
}
public static String getPassword() {
return password;
}
public void setPassword(String password) {
StudentData.password = password;
}
}
public class stoActivity extends Activity {
SHelper db = new SHelper(this);
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_sto);
final EditText fullname=(EditText)findViewById(R.id.fullName);
final EditText password=(EditText)findViewById(R.id.password);
final String fullname=fullname.getText().toString();
final String password=password.getText().toString();
Button registerbutton = (Button) findViewById(R.id.registerButton);
registerbutton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v){
db.add(new StudentData(fullname,password));
Intent it=new Intent(stoActivity.this,otherActivity.class);
stoActivity.this.startActivity(it);
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_register, menu);
return true;
}
}

There's your issue:
public void add(*StudentData studentdata)
{
...
values.put(colName, *StudentData.getName());
values.put(colPassword, *StudentData.getPassword());
...
}
Can you see it? Your statement is referring to the wrong part of the signature. you need to change the StudentData in the body of your method to lower case studentdata to match what is being passed to the method as a parameter. This illegal behavior went by compiled because you have the static modifier in places where i'm not sure is necessary, ex. the getName() and getPassword() methods.

create table with AutoIncrement key, so change method onCreate to the following:
#Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE "+studentTable+"("+colID+" INTEGER PRIMARY KEY AUTOINCREMENT, "+colName+" TEXT,"+colPassword+" TEXT);");
}

You are not inserting any value for the column you have declared as primary Key.

It´s just an assumtion, but I had similar problems if I wanted to save data inside db. In your onCreate-Method at db.execSQL, You got a blank after comma --> "INTEGER PRIMARY KEY, ". I know that SQLite is very sensitive with such kind of input, You have to look exactly at blanks, commas or any other input.

alter table code in android...

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().

To create permanent buttons programmatically

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();