Creating an array while passing it as an argument in Java

Question

Is there a way to create an array of objects as part of a constructor or method? I'm really not sure how to word this, so I've included an example. I have an enum, and one of the fields is an array of numbers. Here is what I tried:

public enum KeyboardStuff {

    QWERTY(1, {0.5f, 1.3f, 23.1f}, 6);
    DVORAK(5, {0.1f, 0.2f, 4.3f, 1.1f}, 91);
    CHEROKEE(2, {22.0f}, 11);

    private int number, thingy;
    private float[] theArray;

    private KeyboardStuff(int i, float[] anArray, int j) {
        // do things
    }

}

The compiler says that the brackets { } are invalid and should be removed. Is there a way I can pass an array as an argument without creating an array of objects beforehand?

Paul Bellora · Accepted Answer · 2011-09-25 18:54:28Z

38

You can try with new float[] { ... }.

public enum KeyboardStuff {

    QWERTY(1, new float[] {0.5f, 1.3f, 23.1f}, 6);
    DVORAK(5, new float[] {0.1f, 0.2f, 4.3f, 1.1f}, 91);
    CHEROKEE(2, new float[] {22.0f}, 11);

    private int number, thingy;
    private float[] theArray;

    private KeyboardStuff(int i, float[] anArray, int j) {
        // do things
    }

}

edited Sep 25, 2011 at 18:54

Paul Bellora

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answered Sep 25, 2011 at 18:49

Vivien Barousse

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Comments

Peter Lawrey · Accepted Answer · 2011-09-25 19:26:16Z

5

Following @Dave's suggest I would use a vararg

QWERTY(1, 6, 0.5, 1.3, 23.1);
DVORAK(5, 91, 0.1, 0.2, 4.3, 1.1);
CHEROKEE(2, 11, 22.0);

private final int number, thingy;
private final double[] theArray;

private KeyboardStuff(int number, int thingy, double... theArray) {
    // do things
}

It is pretty rare that using a float is better than using a double. double has less rounding error and only uses 4 more bytes.

answered Sep 25, 2011 at 19:26

Peter Lawrey

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1 Comment

Tanaki Over a year ago

@Dave too, I almost forgot about this. Thank you for this solution, but I may need to create more than one Object[] parameter, so this wouldn't be ideal in that situation.

Dave Newton · Accepted Answer · 2011-09-25 18:54:48Z

2

Is there a way you can pass an array without creating an array?

No, but you could use varargs to make it mostly-invisible, although that int at the end might need to move.

answered Sep 25, 2011 at 18:54

Dave Newton

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Comments

Arnout Engelen · Accepted Answer · 2015-10-30 07:21:16Z

1

If using Lists's instead of arrays is an option, future versions of Java might start supporting a 'collection literals' syntax which unfortunately doesn't seem to have made it into Java 8:

public enum KeyboardStuff {

    QWERTY(1, [0.5f, 1.3f, 23.1f], 6);
    DVORAK(5, [0.1f, 0.2f, 4.3f, 1.1f], 91);
    CHEROKEE(2, [22.0f], 11);

    private int number, thingy;
    private List<Float> values;

    private KeyboardStuff(int i, List<Float> values, int j) {
        // do things
    }

}

edited Oct 30, 2015 at 7:21

answered Sep 25, 2011 at 19:33

Arnout Engelen

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1 Comment

harperska Over a year ago

It looks like collection literals did not make it into Java 8 either, unfortunately.

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