Need help for doing something with Java

[Cryosec]

I'm back here to ask something else for an android app I'm coding

 

In the main activity, when user presses the floating action button, a second activity is launched. Here the users adds stuff to a list (name, price, quantity), which then gets saved to an SQLite table.

What I need to do is: for every time the user presses the FAB in the MainActivity, a new table must be created (with unique table name), and a new entry in the listview of mainactivity, related to the newly created table, should appear (and also be saved).

I can't find a way to make this possible, any ideas?

 

(I already have a DBHelper class)

[Stardar1]

3 minutes ago, Cryosec said:

I'm back here to ask something else for an android app I'm coding

 

In the main activity, when user presses the floating action button, a second activity is launched. Here the users adds stuff to a list (name, price, quantity), which then gets saved to an SQLite table.

What I need to do is: for every time the user presses the FAB in the MainActivity, a new table must be created (with unique table name), and a new entry in the listview of mainactivity, related to the newly created table, should appear (and also be saved).

I can't find a way to make this possible, any ideas?

 

(I already have a DBHelper class)

Well you could make a list of tables. 

[Cryosec]

2 minutes ago, Stardar1 said:

Well you could make a list of tables. 

aaand how could I tell the DBHelper to use a unique table name each time the button is pressed? also, what would be the variable type for a table (assuming you intend List<item>)?

[Stardar1]

3 minutes ago, Cryosec said:

aaand how could I tell the DBHelper to use a unique table name each time the button is pressed? also, what would be the variable type for a table (assuming you intend List<item>)?

Rather than a unique name you would have an index in the list, as Java cannot create and store variable with unique names while running the code. 

 

as for the tables, and their types, that should be easy to figure out. (I have not used them)

[Cryosec]

3 minutes ago, Stardar1 said:

Rather than a unique name you would have an index in the list, as Java cannot create and store variable with unique names while running the code. 

 

but I wouldn't have different tables, as they all have the same name. SQLite would create the first table, and when I need to create the next table, at index 1, it would find a table in the database with the same name, so it won't create a new one.

 

But if you mean instead of a TABLE_NAME I used the index in the list, then I'd have to change the onCreate and onUpdate functions in the DBHelper, which would give me an error (onCreate and onUpdate won't be called anymore, as they won't be the default function the class expects)

[Stardar1]

1 minute ago, Cryosec said:

but I wouldn't have different tables, as they all have the same name. SQLite would create the first table, and when I need to create the next table, at index 1, it would find a table in the database with the same name, so it won't create a new one.

 

But if you mean instead of a TABLE_NAME I used the index in the list, then I'd have to change the onCreate and onUpdate functions in the DBHelper, which would give me an error (onCreate and onUpdate won't be called anymore, as they won't be the default function the class expects)

Can you not just create a new table object in the list?

 

 

list.add(new Table(<args));

[Cryosec]

2 minutes ago, Stardar1 said:

Can you not just create a new table object in the list?

tables are created with SQL queries within the DBHelper class:

 

Spoiler

private static final int DATABASE_VERSION = 1;
    private static final String DATABASE_NAME = "shopList";
    private static final String TABLE_NAME = "shopTable";
    // Table column names
    private static final String KEY_ID = "id";
    private static final String KEY_NAME = "Name";
    private static final String KEY_PRICE = "Price";
    private static final String KEY_QTY = "Quantity";

--snip--

public void onCreate(SQLiteDatabase db) {

        String CREATE_SHOP_TABLE = "CREATE TABLE IF NOT EXISTS " + TABLE_NAME + "("
                + KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT,"
                + KEY_PRICE + " INTEGER," + KEY_QTY + " INTEGER" + ")";
        db.execSQL(CREATE_SHOP_TABLE);
    }

    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
        onCreate(db);
    }

 

 

[Stardar1]

Just now, Cryosec said:

tables are created with SQL queries within the DBHelper class:

 

  Reveal hidden contents

private static final int DATABASE_VERSION = 1;
    private static final String DATABASE_NAME = "shopList";
    private static final String TABLE_NAME = "shopTable";
    // Table column names
    private static final String KEY_ID = "id";
    private static final String KEY_NAME = "Name";
    private static final String KEY_PRICE = "Price";
    private static final String KEY_QTY = "Quantity";

--snip--

public void onCreate(SQLiteDatabase db) {

        String CREATE_SHOP_TABLE = "CREATE TABLE IF NOT EXISTS " + TABLE_NAME + "("
                + KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT,"
                + KEY_PRICE + " INTEGER," + KEY_QTY + " INTEGER" + ")";
        db.execSQL(CREATE_SHOP_TABLE);
    }

    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
        onCreate(db);
    }

 

 

Then make a class that creates a table. Store those in the list. 

[Cryosec]

10 minutes ago, Stardar1 said:

Then make a class that creates a table. Store those in the list. 

A class that creates a table would be a copy of DBHelper, thus still keeping the same name for each table created

[Stardar1]

Just now, Cryosec said:

A class that creates a table would be a copy of DBHelper, thus still keeping the same name for each table created

But that doesnt matter because you would be creating a new instance every time in the list. 

 

[Cryosec]

3 minutes ago, Stardar1 said:

But that doesnt matter because you would be creating a new instance every time in the list. 

It would matter, as the database would find a table with the same name with the query "CREATE TABLE IF NOT EXISTS", preventing the creation of the new table

[Stardar1]

Just now, Cryosec said:

It would matter, as the database would find a table with the same name with the query "CREATE TABLE IF NOT EXISTS", preventing the creation of the new table

Java cannot create variables with your custom names once it has been compiled, not unless the table has a field that takes in a string for it's name. 

[Cryosec]

2 minutes ago, Stardar1 said:

Java cannot create variables with your custom names once it has been compiled, not unless the table has a field that takes in a string for it's name. 

theeeen the database idea won't work.

I'll need another way to save entries in a ListView, and also be able to load a specific saved list from an entry in another listview of another activity

[Stardar1]

Just now, Cryosec said:

theeeen the database idea won't work.

I'll need another way to save entries in a ListView, and also be able to load a specific saved list from an entry in another listview of another activity

You can use a file...

[Cryosec]

2 minutes ago, Stardar1 said:

You can use a file...

that's something I never attempted to do. What would be the file layout and type for something like this?

[Stardar1]

Just now, Cryosec said:

that's something I never attempted to do. What would be the file layout and type for something like this?

Probably a .txt, as for the format insie it, that is for you to determine, as you are reading it. 

[Cryosec]

2 minutes ago, Stardar1 said:

Probably a .txt, as for the format insie it, that is for you to determine, as you are reading it. 

So if I got this correctly, I should create a txt file when a new list is created (the FAB button in the mainactivity), and for every new entry, I'll save it also to the file.

Something like this (the txt):

name,price,qty;
name,price,qty;
name,price,qty;

Then, to read the file and re-create the list, I can make it read until the comma, use the input as "name", read to the next comma, and so on. Sounds good, what do you think?

[Stardar1]

1 minute ago, Cryosec said:

So if I got this correctly, I should create a txt file when a new list is created (the FAB button in the mainactivity), and for every new entry, I'll save it also to the file.

Something like this (the txt):

name,price,qty;
name,price,qty;
name,price,qty;

Then, to read the file and re-create the list, I can make it read until the comma, use the input as "name", read to the next comma, and so on. Sounds good, what do you think?

Will work great. Is the user inputing those parameters?

[Cryosec]

1 minute ago, Stardar1 said:

Will work great. Is the user inputing those parameters?

In the second activity, user will be prompted (after pressing another FAB) with a popup. This has 3 EditTexts where the user will input the name, the price and the quantity (stored as String name, int price, int qty. obviouslty I can convert price and qty to string if needed)

[Stardar1]

4 minutes ago, Cryosec said:

In the second activity, user will be prompted (after pressing another FAB) with a popup. This has 3 EditTexts where the user will input the name, the price and the quantity (stored as String name, int price, int qty. obviouslty I can convert price and qty to string if needed)

ok. 

[Cryosec]

2 minutes ago, Stardar1 said:

ok. 

Well, thanks for helping me  

[Fetzie]

You would probably want to use a double or BigInt for pricing to allow for decimals (use Double.toString(doublevalue); to make it a String if you want to). That gives you the option to have prices like "$5.99" that you can perform Math.function() on later.

 

[Cryosec]

3 minutes ago, Fetzie said:

You would probably want to use a double or BigInt for pricing to allow for decimals (use Double.toString(doublevalue); to make it a String if you want to). That gives you the option to have prices like "$5.99" that you can perform Math.function() on later.

 

that actually helps, I was going to do some research on what should be the best type. Thanks!