Java basic grammar

Learning log

Program flow

Write the source code.
Compile the source code with a compiler and convert it to bytecode.
The interpreter translates bytecode into machine language to run the CPU

--The extension of the java file will be .java.

`name of the class.java`


public class class name{
public static void method name(String[] args) {
    //processing
  }
}

The inside of a class is called a class block, and the inside of a method is called a method block.

System.out.println();

Output the value taken as an argument.

Variable definition

Variable declaration statement

`python`


Data type variable name;

//For example
int age;  //Declare the variable first.
age = 30; //Next, assign the data to the variable.

You can also declare and assign variables at the same time. (Called variable initialization)

`python`


Data type variable name=value;

//For example
int age = 30;

Data type type

Classification	Model name	Data to store	Example
integer	long	大きなinteger	long worldPeople; //World population
	int	Ordinary integer	int salary; //Salary amount
	short	Small integer	short age; //age
	byte	Smaller integer	byte glasses; //Number of glasses you have
a few	double	Ordinary decimal	double pi; //Pi
	float	Decimal numbers that can be a little vague	float weight//body weight
Boolean value	boolean	true or false	boolean isMarried;//Whether you are married or not
letter	char	１つのletter	char initial; //イニシャル1letter
String	String	Character sequence	String name; //My name

Operand operator

`python`


age = 20 + 5; //Operator=Or+以外のageOr20、5(変数Or値のこと)Is called the operand.
//All formulas consist only of these two elements.

Among the operands, the values assigned to variables and the values of numbers, characters, and character strings described in the source code are called literals. Each literal has a data type.

--Assignment operator

`python`


a = 10;  // =>10,Substitute the right side for the left side
a += 10; // =>a = a +10. When the left side and the right side are added and assigned to the left side, and the characters are added, the left side and the right side are connected.
a -= 10; // =>a = a -10. Subtract the left and right sides and substitute for the left side
a *= 10; // =>a = a *10. Multiply the left side and the right side and substitute for the left side
a /= 10; // =>a = a /10. Divide the left and right sides and substitute for the left side
a %= 10; // =>a = a %10. Divide the left and right sides and substitute the remainder for the left side

--Increment decrement operator

`python`


a++(Or++a); // =>a +1, only 1 is added to a.
a--(Or--a); // =>a -1, only 1 is subtracted for a.

Initialization of constants

Variables can be overwritten. However, since the tax rate and the circumference rate are basically the same, it would be troublesome if they could be overwritten. Therefore, such variables are assigned as constants.

`python`


Data type constant name=value;

final int PRICE = 100;
//Constant names are generally capitalized