Java

ลำดับตอนที่ #3 : Java I - Type Conversion

Implicit Type Conversion

Type Conversion

          We learned about concatenating Strings, but can we concatenate an integer and a string? You can, using type conversion. In Java, types can be converted both implicitly and explicitly. In the example, 23 is converted to "23". This is because int gets converted to String implicitly when you add them together.

Rules of Calculation

          Before learning about implicit type conversion between an int and a double, there's one important rule to be careful of. Calculations between two identical types will return the same type. Therefore, 5 / 2 returns 2, not 2.5.

Int and Double Calculations

          What happens when we do calculations with an int and a double? In this case, the int will be implicitly converted to a double, and the result will be a double. So, both 5 / 2.0 and 5.0 / 2 will be 2.5. Since integers can be written as decimals (like 5 and 5.0), Java automatically converts them.

Explicit Type Conversion

Calculating int Type Numbers

          We've learned that 5 / 2, a calculation of integers, results in 2.  What should we do if we want to find a more accurate value when dividing an integer by another integer?

Cast

          Explicit type conversion, also known as casting, solves that for us. You can convert an integer to a double by casting it, like in the image below (※ you only have to cast one of the integers to a double, as we learned in the previous lesson).

Final Project

          It's time for the final project. You'll create a program that prints your name, age, height, weight, and BMI. Let's give it a try!