Regarding Java variable usage

Summary of Java variables

It outputs what you have learned about Java variables. Reference book: Introduction to Java that can be understood clearly

9 typical data types

Classification	Model name	Data to store	frequency of use
integer	byte	Very small integer	△
	short	Small integer	△
	int	Ordinary integer	◎
	long	Large integer	△
a few	float	A few that can be a little vague	△
	double	Ordinary decimal	○
Boolean value	boolean	true or false	○
letter	char	One character	△
String	String	Character sequence	◎

Supplement

There is no problem if you basically use "int type" for integers. For a few, there is basically no problem if you use "double type". Enclose the characters in quotation marks. ('House') Enclose the string in double quotes. ("Let's dance at home")

Variable declaration method

 int = age;  //Variable declaration
 age = 22;  //Substitute "22" for age
 //Or
 int age = 22;  //Variable declaration and assignment in one line

 System.out.println(age);  //output