Using object in another class

Question

I want to use inst in another class SubscribeTables() I need it with all of its data. I tried to make a getter in Main() but it didnt work. Maybe i can pass it to another class somehow? Can someone help me with it?

Lets say i need to call inst.isConnected() in SubscribeTables()

public class Main {
    public static void main(String[] args) throws IOException {

      // Setup NT4 Client
      NetworkTableInstance inst = NetworkTableInstance.getDefault();
      inst.startClient4("FRC Stat Track");
      selectNetworkTablesIP(inst, 5883);
      // Connects after ~100ms


      new SubscribeTables();
}

You can create a constructor for SubscribeTables which takes a NetworkTableInstance as a parameter, and create a field in SubscribeTables. — tgdavies
– tgdavies, Commented Jan 25, 2023 at 22:25
Why is all of your code in the static main world? If you need OOP objects that interact, then use OOPs. Declare your inst field as an instance field with getters/setters and usual restrictions and controls. — Hovercraft Full Of Eels
– Hovercraft Full Of Eels, Commented Jan 25, 2023 at 22:26

Enowneb · Accepted Answer · 2023-01-26 05:59:37Z

So to consolidate, in terms of code, your SubscribeTables class should look like this:

public class SubscribeTables {
    private NetworkTableInstance instance;

    // Make a constructor to take NetworkTableInstance
    public SubscribeTables(NetworkTableInstance instance) {
        this.instance = instance;
    }

    public void function() {
        // Use the NetworkTableInstance for every function in this Class
        boolean isConnected = instance.isConnected();
    }
}

And the way to create a SubscribeTables object:

SubscribeTables tables = new SubscribeTables(inst);

Sudarshana Gurusinghe · Accepted Answer · 2023-01-25 22:34:07Z

0

The scope of NetworkTableInstance inst is limited to the lifecycle of main method as your new class is not aware. You have 2 options if you still want to do it in this way - but not recommened.

Pass the instance of NetworkTableInstance as a constructor paramater to SubscribeTables
Pass the instance of NetworkTableInstance to the respective methods as a method parameter you need to call on SubscribeTables

answered Jan 25, 2023 at 22:34

Sudarshana Gurusinghe

462 bronze badges

1 Comment

Elo Benc Over a year ago

I couldn't do something like NetworkTablesInstance inst = new NetworkTablesInstance();

Oleksandr Myronets · Accepted Answer · 2023-01-25 22:34:32Z

0

You can supply link of object A(type NetworkTableInstance) to object B(type SubscribeTables) either by argument in constructor or by argument in setter method. In both cases SubscribeTables class should have field of type NetworkTableInstance to put NetworkTableInstance object from constructor or setter arguments into the field.

answered Jan 25, 2023 at 22:34

Oleksandr Myronets

11010 bronze badges

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