How to use an array containing Pair objects?

Asked Jan 03 '21 at 12:25

Active Jan 03 '21 at 21:23

Viewed 45 times

My array:

private Object[] arr = new Pair[initialCapacity];

My Pair class:

private static class Pair<V> {
    private String key;
    private V value;

    public Pair(String key, V value) {
        this.key = key;
        this.value = value;
    }
}

I'm trying to get the properties of the objects like this:

arr[startPos].key

but I get the error "cannot find symbol - variable key"

asked Jan 03 '21 at 12:25

Wiggiwoo

Don't declare the array an array of Object, since even though you assigned a Pair array to the variable, Java only knows that the variable holds Objects – Hovercraft Full Of Eels Jan 03 '21 at 12:27
Rather, declare it `private Pair[] arr = new Pair[initialCapacity];` – Hovercraft Full Of Eels Jan 03 '21 at 12:28
@HovercraftFullOfEels I declared it like Pair[] instead and now I can find the key, but still not the value? – Wiggiwoo Jan 03 '21 at 12:30
I suggest a second duplicate: https://stackoverflow.com/questions/2770321/what-is-a-raw-type-and-why-shouldnt-we-use-it – luk2302 Jan 03 '21 at 12:31
If you need key value pairs why not use a Map? Arrays only know int indices and are not best for your situation – Hovercraft Full Of Eels Jan 03 '21 at 12:31
The task wants me to use an array @HovercraftFullOfEels – Wiggiwoo Jan 03 '21 at 12:32
You also need to give the class public getter and possibly setter methods – Hovercraft Full Of Eels Jan 03 '21 at 12:35
1

And the raw type will bite OP as well, can you add that as a duplicate as well @HovercraftFullOfEels ? – luk2302 Jan 03 '21 at 12:36
1

@luk, yes, you mean [this question](https://stackoverflow.com/q/2770321/522444), and you of course are correct, but I can't right now since I am on my phone, and the phone app has limitations – Hovercraft Full Of Eels Jan 03 '21 at 12:39
@HovercraftFullOfEels obtaining the key works now, but I can't get the value, it says "incompatible types: java.lang.object cannot be converted to V" – Wiggiwoo Jan 03 '21 at 12:49
1

Read this: [What is a raw type and why shouldn't we use it?](https://stackoverflow.com/questions/2770321/what-is-a-raw-type-and-why-shouldnt-we-use-it) – luk2302 Jan 03 '21 at 12:50

How to use an array containing Pair objects?

0 Answers0