static variable declaration in class java [duplicate]

Question

Why is this declaration wrong? This declaration leads to identifier expected error

class Abc{
    static ArrayList<Integer> p;
    p = new ArrayList<Integer>(); // identifier expected error
}

or just do it like this: static ArrayList<Integer> p = new ArrayList<Integer>(); .. better would be to code to interfaces and use the more up to date way to work with generics: static List<Integer> p = new ArrayList<>(); — Stultuske
– Stultuske, Commented Feb 16, 2018 at 9:11
"Why is this declaration wrong?" p = new ArrayList<Integer>(); is not declaration, it is initialization. — Pshemo
– Pshemo, Commented Feb 16, 2018 at 9:14

T.J. Crowder · Accepted Answer · 2018-02-16 09:16:21Z

2

You have a freestanding assignment statement in your class body. You can't have step-by-step code there, it has to be within something (an initializer block, a method, a constructor, ...). In your specific case, you can:

Put that on the declaration as an initializer

static ArrayList<Integer> p = new ArrayList<>();

Wrap it in a static initialization block

static {
    p = new ArrayList<Integer>();
}

More in the tutorial on initializing fields.

answered Feb 16, 2018 at 9:16

T.J. Crowder

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Comments

ibenjelloun · Accepted Answer · 2018-02-16 09:41:52Z

0

This is the right way to do it :

import java.util.ArrayList;

public class Abc {
    static ArrayList<Integer> p;
    static {    
        p = new ArrayList<Integer>(); // works
    } 
}

edited Feb 16, 2018 at 9:41

ibenjelloun

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answered Feb 16, 2018 at 9:16

RCInd

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2 Comments

Stultuske Over a year ago

that's a working way to do it, plenty of possible improvements though.

RCInd Over a year ago

true. the code pasted is erroneous. what i meant was that this the correct syntax (braces)

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