Do you confident about primitive types and arithmetic operators in Java? (+, -, *, /, %, ++, --)

Let's go through some examples!

Example 1: What do you think about the following code? (True or false)

 short s1 = 10; short s2 = 11; short s3 = s1 + s2;

The answer is false. There will be a compilation error on line 3. Types as "byte", "short", and "char" are automatically promoted to "int" when used in expressions. So, the result of the "s1 + s2" expression is of type "int".

To resolve this, you have two options:

1. Change the type of s3 from "short" to "int":

    int s3 = s1 + s2;
   

2. Cast the result to "short" before assigning to s3:

    short s3 = (short) (s1 + s2);
   

Example 2: What do you think about this statement? (True or false)

float a = 123.456;

The answer is false. This will result in a compilation error because in Java, a floating-point number like "123.456" is considered a "double" type by default.

To fix this, either add the 'f' suffix or change the variable type:

 // Using the 'f' suffix float a = 123.456f; // Alternatively, change the type to double double a = 123.456;

Example 3: How about this statement? (True or false)

double d1 = 12.5;
float f1 = 12.5f;
float result = (float) (d1 + f1);

This will result in a compilation error on line 3. When performing arithmetic operations, Java automatically promotes types to the larger one. You have three solutions:

1. Cast d1 to "float" before addition:

    float result = (float) d1 + f1;
   

2. Cast the result to "float" after addition:

    float result = (float) (d1 + f1);
   

3. Change the result type to "double":

    double result = d1 + f1; // Recommended
   

 Note: For "long" type, use 'l' or 'L' suffix to specify the value.

Example 4: What is the result of this statement?

short s = (short) 1921222;
System.out.println(s);

The result printed is 20678 = 1921222 % (2^16/2).

Example 5: What is the result of this statement?

System.out.println((2147483647 + 1));
// Note: 2^32/2-1 = 2147483647

The printed result is "-2147483648". When values exceed the range of "int", they wrap around.

Example 6 (last): What are the results of the following code?

// 1.
long x = 10;
int y = 5;
y = (int) (x * y); // 2.
long x = 10;
int y = 5;
y *= x;

The first statement results in a compilation error on line 3. To fix it, cast the result explicitly.

The second statement works fine because of implicit type casting.