Eliminating redundancy in multiple constructors

Question

If anyone could tell me whether my code is redundant (and if it is, possible solutions to eliminate redundancy) I would very appreciate it.

public class Question {
  private Queue<Double> a;

  public Question(double XXX) {
     a = new LinkedList<Double>();  // REDUNDANT?
     ......
  }

  public Question(double[] YYY) {
     a = new LinkedList<Double>();  // REDUNDANT?
     ......
  }
}

Basically, one constructor takes in a double value while the other constructor takes in an array of double numbers. Is there any way to instantiate the Queue only once?

Robert Louis Murphy · Answer 1 · 2012-04-14T01:26:44.787

3

When using Java 7 and NetBeans or other IDEs, the IDE may flag

a = new LinkedList<Double>();

as redundant, you can use

a = new LinkedList<>();

instead. But if you are just asking about actual redundancy in your code, use:

public class Question {
  private Queue<Double> a;

  public Question() {
     a = new LinkedList<>();
  }

  public Question(double XXX) {
     this();
     ......
  }

  public Question(double[] YYY) {
     this();
     ......
  }
}

edited Apr 14 '12 at 01:26

answered Apr 14 '12 at 01:21

Robert Louis Murphy

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Thanks! This is the style I was looking for. Can't believe I didn't think of this... – jkface Apr 14 '12 at 01:23

score 3 · Answer 2 · answered Apr 14 '12 at 01:22

3

You can instantiate your variable a while declaring.

public class Question {
   private Queue<Double> a = new LinkedList<Double>();

   ...
 }

answered Apr 14 '12 at 01:22

score 2 · Answer 3 · answered Apr 14 '12 at 01:22

2

You can use the this operator to call another constructor with the appropriate arguments.

answered Apr 14 '12 at 01:22

Makoto

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score 1 · Answer 4 · answered Apr 14 '12 at 01:21

1

Put it in the field declaration:

private Queue<Double> a = new LinkedList<Double>();

answered Apr 14 '12 at 01:21

Jordão

55,340
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score 1 · Answer 5 · answered Apr 14 '12 at 01:29

You may also want to consider this:

public class Question {
    private Queue<Double> a;

    public Question(double ... ds) {
        a = new LinkedList<>(Arrays.asList(ArrayUtils.toObject(ds)));
    }
}

This uses the varargs constructor, to which you can pass a single double, multiple doubles, or an array of doubles. So you can do:

new Question(1, 2, 3);
new Question(1);
new Question(new double[] { 1, 2, 3 } );

Note: ArrayUtils is part of the Apache Commons Lang.

Eliminating redundancy in multiple constructors

5 Answers5