运算符
运算符
算数运算符
public class dome6 { //常量 final 修饰符,不存在先后顺序 static final double ip = 3.12; //常量 常量 变量 public static void main(String[] args) { System.out.println(ip);//3.12 long a = 1000000000l; int b = 10; short c = 10; byte d = 10; double e = 3.12; System.out.println(a+b+c);//long System.out.println(c+d+e);//23.12 double System.out.println(b+c+d);//30 为int public class Dome007 { public static void main(String[] args) { //++ -- 一元运算符 自增 自减 //int a = 5; //int b = a++; //System.out.println(a);//a++ 执行完代码后 先给b附值再自增 6 //System.out.println(b);//5 //int a = 5; //int b = ++a; //System.out.println(a);//6 //System.out.println(b);//6 ++a执行代码前,先自增 后给b赋值 int a = 5; int b = a--; System.out.println(a);//4 System.out.println(b);//5 int c = 5; int d = --c; System.out.println(c);//4 System.out.println(d);//4 三元运算符 条件运算符 //x ? y :z 必须掌握 //如果x为真结果为y 反之为z public class Dome10 { public static void main(String[] args) { int rbq = 60; String type = rbq<70 ?"及格":"不及格"; System.out.println(type);
a + b = 30 10 20a - b = -10a * b = 200b / a = 2b % a = 0c % a = 5a++ = 10a-- = 11d++ = 25++d = 27
a = 000101b = 100001a&b = 000001 俩一为1其余取0a|b = 100101 俩0取0其余为一a^b = 111011 对位相同为零 否则为一~a = 111010 零变一 一变0
面试题
怎么计算2*8
2*2*2*2 位运算 效率极高 <<左移相当于*2 >>右移相当于/2 System out printin(2<<3)
字符串连接符
int b = 30; int a = 10; String 字符串 System.out.println(""+a+b);//1030System.out.println(+a+b"" );//40
image-20210416110200853](C:\Users\dell\AppData\Roaming\Typora\typora-user-images\image-20210416110200853.png)
public class Dome8 { public static void main(String[] args) { double pow = Math.pow(2, 3); double pow1 = Math.pow(3, 2); System.out.println(pow); System.out.println(pow1); //与&& 或|| 非!//短路运算 int a = 4; boolean c = (a<4)&&(a++<4); System.out.println(a);//4 System.out.println(c);//执行完a<4判断出来就不执行了 false } }