CODEWITHSUNDEEP
javaconditional-operator
user3055964
user3055964

Reputation: 151

Java Ternary Operations - Accepting Integer

If I have Ternary syntax like this, compiler does not throw any compilation error:

int s = 2;
Double sdf = (s > 3 ?  new Double(12) : new Integer(12));

However if I have this, it is throwing compilation error:

Required type: Double Provided: Integer

Double sdf = (s > 3 ?  new Integer(12) : new Integer(12));

Upvotes: 1

Views: 168

Answers (3)

sarwadnya deshpande
sarwadnya deshpande

Reputation: 119

It's because internally type is pramoted. Integer can be pramoted to double. But double can't be demoted to Integer. Pramotion happens in following way Byte -->Short-->Interger-->Long-->Float -->Double

Upvotes: 1

Vitalii Vitrenko
Vitalii Vitrenko

Reputation: 10405

According to the Conditional Operator ? : specification, in case if one operand is Integer and the other is Double binary numeric promotion is used to resolve the result type.

Based on the rules, in the first example, the result type is Integer but Double in the second one (unboxing + widening).

Upvotes: 2

Gautham M
Gautham M

Reputation: 4935

This happens because if we use wrapped primitive values like in the question (Integer, Float, Double etc.) in a ternary operator, both values will be unboxed and coerced to a common type.

This may result in unexpected results as well.

In the first example, new Integer(12) would be converted to a double as it is the common type. Hence there are no compilation issue.

But in the second example both are Integer which is not compatible with the left hand side type Double.

Example taken from Sonar rule description S2154:

Integer i = 123456789;
Float f = 1.0f;
// Assume condition = true
Number n = (condition) ? i : f; // i is coerced to float. n = 1.23456792E8

To fix this, we need to do explicit casting:

Integer i = 123456789;
Float f = 1.0f;
// Assume condition = true
Number n = condition ? (Number) i : f;  // n = 123456789

Additional suggestion: Do not use new Double() or new Integer() etc. These constructors are deprecated. Instead use valueOf method

Upvotes: 2

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