What is the result of adding a double value to a String?

• A. A double is converted to an integer
• B. A String object is returned
• C. A double is lost
• D. An error is thrown

Answer: (B)

When a double value is added to a String in Java, the result is a new String that represents the concatenation of the String and the string representation of the double value. This occurs because the + operator in Java, when applied to a String, invokes the String concatenation functionality.

When a non-String value (like a double) is combined with a String, Java automatically converts the non-String value to its String representation. For example, if the double value is 3.14 and the String is "Value: ", the result of the operation would be "Value: 3.14". Therefore, the outcome of this operation is indeed a new String object that combines both elements.

This behavior is part of Java's type conversion mechanism, which seamlessly converts other types to Strings during concatenation, making it easy to mix different data types in user-facing outputs without explicit casts or conversions.