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Partitioning the constructor method - a problem with finite values

I wanted to break the constructor of my class into parts. But I have a problem ...

Is it possible to initialize the final value in a method called inside the constructor? Should it be initialized directly in the constructor?

It...

import java.util.Scanner;

public final class A
{
    private final int L;
    private final int D;
    private final int N;

    public A()
    {
        Scanner scanner = new Scanner(System.in);
        this.getFirstLine(scanner);

        /* the rest of the constructor method */
    }

    private void getFirstLine(Scanner scanner)
    {
        this.L = scanner.nextInt();
        this.D = scanner.nextInt();
        this.N = scanner.nextInt();
    }
}

gives me errors similar to The final field A.L cannot be assigned.

So, is this considered an appointment? Yes?

Is there a way to split the constructor to achieve what I wanted?

Thanks in advance.

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5 answers

How about this one.

import java.util.Scanner;

public final class A {

    private final int l;
    private final int d;
    private final int n;

    public A() {
        Scanner scanner = new Scanner(System.in);
        int[] list = this.getFirstLine(scanner);
        l = list[0];
        d = list[1];
        n = list[2];

        /* the rest of the constructor method */
    }

    private int[] getFirstLine(Scanner scanner) {
        return new int[]{scanner.nextInt(), scanner.nextInt(), scanner.nextInt()};
    }
}
+2

You cannot do this according to Java Language Spec :

(§16.9) (§8.8) , ; .

, , . . :

import java.util.Scanner;

public final class A
{
    private final int L;
    private final int D;
    private final int N;

    public A()
    {
        Scanner scanner = new Scanner(System.in);
        this.L = scanner.nextInt();
        this.D = scanner.nextInt();
        this.N = scanner.nextInt();

        /* the rest of the constructor method */
    }
}

, , .

+3

. , , , . getFirstLine :

private A(Scanner scanner)
{
    this.L = scanner.nextInt();
    this.D = scanner.nextInt();
    this.N = scanner.nextInt();
}
+2

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+2

, , , :

import java.util.Scanner;

public final class A
{
    private static final Scanner scanner = new Scanner(System.in);

    private static class FirstLine
    {
        public static int[] get()
        {
            return new int[]
            {
                A.scanner.nextInt(), 
                A.scanner.nextInt(), 
                A.scanner.nextInt()
            };
        }
    }

    private final int L;
    private final int D;
    private final int N;

    public A()
    {
        int[] valuesScanned = FirstLine.get();
        this.L = valuesScanned[0];
        this.D = valuesScanned[1];
        this.N = valuesScanned[2];
    }

    /*JUST TO TEST*/
    public static void main(String[] args)
    {
        A test = new A();
        System.out.println(test.L);
        System.out.println(test.D);
        System.out.println(test.N);
    }
}

, . .

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