Constructor cannot be applied

Question

i was doing this tutorial on Android Studio Development Essentials 6th Edition, the tutorial was about SQLiteDatase so i wrote evrything but i kept on getting an error whenever i try calling the Product Constructor everything is correct on the book but i cant get it right, this is the find Product Constructor and my Product class.

Find product

  public Product findProduct(String productname) {
    String query = "Select * FROM " + TABLE_PRODUCTS + " WHERE " +
            COLUMN_PRODUCTNAME + " = " + productname + ";";
    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery(query, null);
    Product product = new Product();// Cannot be applied
    if (cursor.moveToFirst()) {
        cursor.moveToFirst();
        product.setId(Integer.parseInt(cursor.getString(0)));
        product.setProductName(cursor.getString(1));
        product.setQuantity(Integer.parseInt(cursor.getString(2)));
        cursor.close();
    } else {
        product = null;
    }
    db.close();
    return product;
}

My Product Class

public class Product {
private int id;
private String ProductName;
private int Quantity;

public Product(int _id, String _productname, int _quantity) {
    this.id = _id;
    this.ProductName = _productname;
    this.Quantity = _quantity;
}

public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

public String getProductName() {
    return ProductName;
}

public void setProductName(String productName) {
    this.ProductName = productName;
}

public int getQuantity() {
    return Quantity;
}

public void setQuantity(int quantity) {
    this.Quantity = quantity;
}

}

Thank you.

As you have an overloaded constructor, you MUST add an empty constructor to the Product class. — Rajitha Siriwardena, Oct 31 '16 at 07:27
can you show me were to add please... thank you @RajithaSiriwardena — Mohamed Osman, Oct 31 '16 at 07:30
There is **no need** to be *empty* - only *without parameters*. - @Rajitha Siriwardena — MarianD, Oct 31 '16 at 08:04
@MarianD Oops my bad. Let me rephrase...you MUST add a constructor with empty params, aka a default constructor. — Rajitha Siriwardena, Oct 31 '16 at 08:48

MarianD · Accepted Answer · 2016-10-31T07:58:40.200

3

    public Product(int _id, String _productname, int _quantity) {

is the only constructor in you Product class definition (you don't have any others), so you have to call its constructor with these 3 parameters - instead of

    Product product = new Product();// Cannot be applied

use something as

    Product product = new Product(132, "Wheel", 1000);

Another solution:

Add another constructor in your Product class besides existing one, e. g. an empty one:

    public Product() {}

(it may be located before or after your existing one).

edited Oct 31 '16 at 07:58

answered Oct 31 '16 at 07:32

MarianD

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i know that's how the constructor works am trying to get the data from a cursor not add it by myself – Mohamed Osman Oct 31 '16 at 07:36
You may construct an object and then *change* its properties from a cursor, or add a constructor without parameters - i will extend my answer now. – MarianD Oct 31 '16 at 07:40

score 2 · Answer 2 · edited May 23 '17 at 12:24

2

If You created Your own constructor, the default one is not generated. Please take a look at Java default constructor Regards

edited May 23 '17 at 12:24

Community

1
1

answered Oct 31 '16 at 07:30

Michal W

318
4
11

Constructor cannot be applied

2 Answers2