Multiple choice technology programming languages

What will happen if you attempt to compile and run the following code? Integer ten=new Integer(10); Long nine=new Long (9); System.out.println(ten + nine); int i=1; System.out.println(i + ten);

  1. 19 followed by 20

  2. 19 followed by 11

  3. Error: Can't convert java lang Integer

  4. 10 followed by 1
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C Correct answer
Explanation

The code attempts to add Integer and Long wrapper objects directly using the + operator. Java does not support automatic unboxing and arithmetic between different wrapper object types - Integer + Long is invalid. You must first convert them to primitive types using intValue() or longValue(). The compiler will error on 'ten + nine' because it cannot resolve the + operator for Integer and Long types. The second operation 'i + ten' would work because int auto-unboxes Integer, but the first error prevents compilation.

AI explanation

To answer this question, let's go through each line of code and understand its behavior:

  1. Integer ten = new Integer(10); - This line creates a new instance of the Integer class and assigns the value 10 to it.

  2. Long nine = new Long(9); - This line creates a new instance of the Long class and assigns the value 9 to it.

  3. System.out.println(ten + nine); - This line attempts to print the sum of ten and nine. Since ten is an Integer and nine is a Long, the Java compiler will try to promote ten to a Long before performing the addition. However, this operation is not supported, and it will result in an error.

  4. int i = 1; - This line declares and initializes an integer variable i with the value 1.

  5. System.out.println(i + ten); - This line attempts to print the sum of i and ten. Since ten is an Integer and i is an int, the Java compiler will automatically promote i to an Integer before performing the addition. The sum will be 1 + 10 = 11, and it will be printed as the output.

Therefore, the correct answer is C. Error: Can't convert java lang Integer. The code will fail to compile because the addition of an Integer and a Long is not supported.

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