public class Test1 {

public static void main(String[] args) {

//变量：1.声明数据类型(整数、小数、字符串、....) 2.赋值（赋值符号=，将=右侧 赋给左侧） 3.使用

int myNum = 10;

// int myNum = 10 ; 变量名不能重复

myNum = myNum + 1;

System.out.println(myNum);

byte b = 127;

System.out.println(b);

short s = 1000;// short = int （整数默认是int，但是 = 对于整数自带 整数类型（byte short int long）之间的 转换器）

System.out.println(s);

long lon = 2000000;

System.out.println(lon);

float f = (float) 123.4; //小数默认是double. float = double

float f2 = 123.4f; //小数默认是double. float = double

System.out.println(f);

double d = 123.4;

System.out.println(d);

char c = 'x';

System.out.println(c);

String str = "a";

String str2 = "aaaa";

String str3 = "";

System.out.println(str);

System.out.println(str2);

System.out.println(str3);

int x1 = 1;

int X1 = 1;

int y = 222;

System.out.println(y);

}

}