CODEWITHSUNDEEP
javaarraysconstructor
Fodrigoal
Fodrigoal

Reputation: 79

How to call a constructor of a constructor inside a parameter?

I need to create an Array with objects from another class but the other class use objects of another class in the constructors too... I will try to explain better:

public class BookStore
{
    private String storeName; //e.g. "Jason's New Books"
    private Book[] inventory; // Array of Book objects

    public BookStore()
    {
        inventory = new Book[100];

        inventory[3] = new Book("James Joyce", 2013, "ULYSSES");
    }

I need to create this Book Array but I can't figure out how to put the parameters, because in the Book class the constructor is like this:

public Book(Author author, Date published, String title)

As you can see, this constructor uses objects from another class to initiate, and the other class the constructors are like this:

public Date()

and

public Author()

When I try to compile the BookStore class I get the following error:

"incompatible types: java.lang.String cannot be converted to Author"

Upvotes: 1

Views: 93

Answers (5)

Mohammed Aouf Zouag
Mohammed Aouf Zouag

Reputation: 17132

Use this:

import java.util.Date;

inventory[index] = new Book(
    new Author("Author name"),
    new Date(115, 11, 10), // The 10th of December, 2015
    "book title"
);

Considering that the Author class has defined such a constructor:

public class Author {
    private String name;
    // Other member variables

    public Author(String name) {
         this.name = name;
    }

    // Other methods
}

Upvotes: 5

Thomas Kläger
Thomas Kläger

Reputation: 21490

The answer from @Sparta has one problem: the month number in java.util.Date is zero-based (January is 0, February is 1, etc) and wraps around, and the year is 1900-based, so new Date(2015, 12, 10) is not the "10th of December, 2015" but "10th of January 3916"

Sorry, would have liked to comment on your answer but I do not yet have enough reputation...

Upvotes: 1

civam
civam

Reputation: 116

Since your Book class constructer Book(Author author, Date published, String title) accepts 3 parameters as following

  1. First parameter is object of Author class
  2. Second parameter is object of Date
  3. Third parameter is String variable

And you are using String, so its throughing that error

Hence, instead of using 

inventory[3] = new Book("James Joyce", 2013, "ULYSSES");

Use

Author objAuthor = new Author();
Date objDate = new Date();
inventory[3] = new Book(objAuthor, objDate, "ULYSSES");

Upvotes: 1

benscabbia
benscabbia

Reputation: 18072

You're almost there, you just need to create an instance of each object:

private Book[] inventory; // Array of Book objects

    public BookStore()
    {
        inventory = new Book[100];
        inventory[3] = new Book(new Author(), new Date(), "title");

You could alternatively do something like: 

        Author author = new Author();
        Date date = new Date();

        inventory[3] = new Book(author, title, "title");

You will need to pass in the required parameters for each object to match your constructor

Upvotes: 1

Eran
Eran

Reputation: 393846

If you only have parameterless constructors in the Date and Author classes, you'll have to create the instances using multiple statements :

Author author = new Author();
author.setName("James Joyce"); // assuming such a method exists
Date date = new Date();
date.setYear(2013); // assuming such a method exists
inventory[3] = new Book(author, date, "ULYSSES");

Upvotes: 2

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