changing the size of an array from a method in java

Question

I have a 2D array and I want to make the size of the array the same as the number of appointments. The number of appointments is found in another class with this line

numOfAppointments = DB.numOfAppointmentsByUser(loggedInUserID);

And I declare the array at the top of the program so it is accessible from the whole program, this is that:

String[][] data = new String[numOfAppointments][2];

But I cant call the numOfAppointments above the data array because it isn't in a method and gives this error: error: <identifier> expected and if I call the numOfAppointment in a method then I will need to declare the data array in that method so that I can use the value from numOfAppointments as the size in the array.

How can I make it so that I can declare the array at the top of the program so it is accessible from all methods but at the same time call the numOfAppointments variable so that I can create the size of the array.

I have tried placing them both in a constructor like this:

numOfAppointments = DB.numOfAppointmentsByUser(loggedInUserID);

public String[][] data = new String[numOfAppointments][2];

I tried to make the array public in the constructor instead but it gives the error illegal start of expression and If I remove the public then the data array isn't accessible from any other method since it isn't public and is a child of that method. Thanks for any help.

What's the purpose of static word? :)

Luai Ghunim
– Luai Ghunim

2017-11-12 20:40:46 +00:00
Commented Nov 12, 2017 at 20:40 — Luai Ghunim
– Luai Ghunim, Commented Nov 12, 2017 at 20:40

Jacob G. · Accepted Answer · 2017-11-12 20:45:00Z

3

You need to move the following declaration outside of the constructor to make it available globally!

public String[][] data;

public Constructor(...) {
    int numOfAppointments = DB.numOfAppointmentsByUser(loggedInUserID);

    data = new String[numOfAppointments][2];
}

edited Nov 12, 2017 at 20:45

answered Nov 12, 2017 at 20:41

Jacob G.

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2 Comments

Andrew Harris Over a year ago

wow that was so simple, been trying to solve it for ages. That did it, thanks a lot :)

Timothy Truckle Over a year ago

a constructor should only assign values to member variables. It should not call methods in other classes and/or objects! Therefore the number of appointments should be passed as constructor parameter.

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