java - Cannot convert Integer to int

Question

I am stuck at this problem for ages. Basically I cannot convert Integer to int.

class CheckOdd implements Check<Integer>
{
  public <Integer> boolean check(Integer num)
  {
    int i = (Integer) num;
    return (i % 2 != 0);
  }
}

I have tried using
int i = (Integer) object; int i = (int) object; intValue()
but still no luck. If I use int i = (Integer) object; it produce error:incompatible types. If I use int i = (int) object; it produce error: inconvertible types.

Please Help. Thank you in advance.

It is a bad practice to write yourself a wrapper around existing wrappers. java.lang.Integer works fine. If you need an integer implementation with more features, I would invite you to rethink your design and naming conventions before really writing yourself a new Integer class. — Eric Tobias
– Eric Tobias, Commented Nov 24, 2014 at 7:46
@EricTobias, while you are correct, I am not sure that the OP intentionally attempts create a wrapper, rather the issue is caused of misused generics. — stackh34p
– stackh34p, Commented Nov 24, 2014 at 8:15

Elliott Frisch · Accepted Answer · 2014-11-24 07:34:42Z

10

You've replaced java.lang.Integer with a generic type which you have named Integer

public <Integer> boolean check(Integer num) // <-- not a java.lang.Integer

should be

public boolean check(Integer num)

answered Nov 24, 2014 at 7:34

Elliott Frisch

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Comments

Shriram · Accepted Answer · 2014-11-24 07:35:20Z

3

After java 1.5 Autoboxing was supported. So you can use

int i = num;

answered Nov 24, 2014 at 7:35

Shriram

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1 Comment

Elliott Frisch Over a year ago

You mention Autoboxing but your example is actually the reverse; Autounboxing. Also, with OP's generic this would not have worked because <Integer> was a generic type (and not java.lang.Integer).

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