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Java Numeric Promotion in Conditional Expression

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  • Difficulty Level : Medium
  • Last Updated : 16 Dec, 2021

With recurrence use of if-else condition in programming which is tend to occur no matter how much we optimize our code. So taking this factor into consideration, conditional operator was introduced making our job of writing code easier as it do have a specific syntax in accordance to which it does check the condition passed to it. The conditional operator ? : uses the boolean value of one expression to decide which of two other expressions should be evaluated. Let us do have an illustration to get used to with its syntax.

Illustration:

Object obj ;
if (true) {
    obj = new Integer(4) ;
} else {
    obj = new Float(2.0);
}

So, with the usage of conditional operator we expect the expression whose syntax is as follows:

Object obj = true ? new Integer(4) : new Float(2.0));

Note: But the result of running the code gives an unexpected result.

Example:

Java




// Java Program to Demonstrate
// Replacing of Conditional Operator
// with If-else and viceversa
 
// Importing required classes
import java.io.*;
 
// Main class
class GFG {
 
    // Main driver method
    public static void main (String[] args) {
 
        // Expression 1 (using ?: )
        // Automatic promotion in conditional expression
        Object o1 = true ? new Integer(4) : new Float(2.0);
 
        // Printing the output using conditional operator
        System.out.println(o1);
 
        // Expression 2 (Using if-else)
        // No promotion in if else statement
        Object o2;
        if (true)
            o2 = new Integer(4);
        else
            o2 = new Float(2.0);
 
        // Printing the output using if-else statement
        System.out.println(o2);
    }
}


Output:

According to Java Language Specification Section 15.25, the conditional operator will implement numeric type promotion if there are two different types as 2nd and 3rd operand.  The rules of conversion are defined at Binary Numeric Promotion. Therefore, according to the rules given, If either operand is of type double, the other is converted to double and hence 4 becomes 4.0. Whereas, the, if/else construct, does not perform numeric promotion and hence behaves as expected.

This article is contributed by Deepak Garg. If you like GeeksforGeeks and would like to contribute, you can also write an article and mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.


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