Java study # 3 (type conversion and instruction execution)

About type conversion

--double d = 3; ← You can assign an int type 3 to a double type variable, --String s = "Best" + 3; ← You can concatenate String type and int type. This is because Java automatically evaluates and converts expressions.

Three types of type conversion

1. Automatic conversion at the time of substitution
2. Explicit type conversion
3. Automatic type conversion during calculation

The automatic type conversion at the time of assignment seems to be that the value is automatically converted to the box and assigned only when the value of "small type" is assigned to the variable of "large type". As an example

float f = 3;
double d = f;

Even so, when it is output, f is converted to 3.0 and d is also converted to 3.0 and substituted. So, if you put a decimal point in the int type, an error will occur. However, there seems to be a method that can be forcibly assigned ...

int a = (int)3.2；

↑ Instruction to convert 3.2 to int and assign This forced instruction (* int) is called a cast operator.

• Enter the conversion destination type name in parentheses. There is a risk with this method as it tries to force the data to be converted even if some of the original data is lost.

int　a　=　(int)3.2;

Is output, 3 is displayed. Is this the last resort because you are often asked to be accurate? Is this a fairly used technique ...? I'm scared personally so I don't want to use it (^ o ^)

Instruction execution statement

System.out.println("Ranka");

↑ This is the statement of instruction execution In other words, it is in the form of the name (argument); of the command to be called.

Type of instruction

1. System.out.print (); ← Display characters without line breaks.
2. int m = Math.max (①, ②); ← Compare the two values and substitute the larger number.
3. int n = Integer.parseInt (①); ← Convert a character string to a number.
4. int r = new java.util.Random (). nextInt (①); ← Instruction to generate and assign random numbers
5. String input = new java.util.Scanner (System.in) .nextInt (); ← Accepts one line of character string input from the keyboard
6. int input = new java.util.Scanner (System.in) .nextInt (); ← Accepts one integer input from the keyboard

That's why the second chapter is over! After that, I will try the exercises that are prepared. (Because I started working on it earlier than I expected today, w) I haven't been able to memorize it when I get to this point, but I'm excited to be able to write small games using what I've learned ^ _ ^ I was studying with Umesh in one hand today, so I feel tipsy ... Good night (´ ･ ω ゞ)