基本运算符

 

 

package Operator;

public class Demo01 {
    public static void main(String[] args) {
        //二元运算符
        //ctrl + D:复制当前行到下一行
        int a = 10;
        int b = 20;
        int c = 25;
        int d = 25;
        System.out.println(a + b);//30
        System.out.println(a - b);//-10
        System.out.println(a * b);//200
        System.out.println(a / b);//0
        System.out.println(a / (double) b);//0.5

    }
}

 

package Operator;

public class Demo02 {
    public static void main(String[] args) {
        long a = 123123123123L;
        int b = 123;
        short c = 10;
        byte d = 8;
        System.out.println(a + b + c + d);//123123123264 long
        System.out.println(b + c + d);//141 int
        System.out.println(c + d);//18 int
        //cast：转换

    }
}

 

package Operator;

public class Demo03 {
    public static void main(String[] args) {
        //关系运算符返回的结果：正确、错误 布尔值
        int a = 10;
        int b = 20;
        int c = 22;

        System.out.println(a > b);//false
        System.out.println(a < b);//true
        System.out.println(a == b);//false
        System.out.println(a != b);//true
        System.out.println(c % a);//22/10=2...2   % 取余：模运算
    }
}

 

package Operator;

public class Demo04 {
    public static void main(String[] args) {
        // ++   --  自增、自减
        int a = 3;
        int b = a++;//执行完这行代码后，先给b赋值，再自增
        //a = a + 1
        System.out.println(a);//4
        //a = a + 1
        int c = ++a;//执行这行代码前，先自增，再给c赋值

        System.out.println(a);//5
        System.out.println(b);//3
        System.out.println(c);//5

        //幂运算 2^3 = 8   2 * 2 * 2 = 8
        //很多运算，会使用一些工具类来操作！
        double pow = Math.pow(2,3);
        System.out.println(pow);//8.0


    }
}

 

package Operator;
//逻辑运算符
public class Demo05 {
    public static void main(String[] args) {
        //与and 或or 非：取反
        //&&：逻辑与运算：两个变量都为真，结果才为真
        //||：逻辑或运算：两个变量有一个为真，结果才为真
        //！：真-假  假-真
        boolean a = true;
        boolean b = false;
        System.out.println("a && b :" + (a && b));//false
        System.out.println("a || b :" + (a || b));//true
        System.out.println("!(a && b) :" + !(a && b));//true

        //短路运算
        int c = 5;
        boolean d = (c < 4 )&&(c++ < 4);
        System.out.println(d);//false
        System.out.println(c);//5

    }
}

 

package Operator;

public class Demo06 {
    public static void main(String[] args) {
        /*
        A = 0011 1100
        B = 0000 1101
        ---------------------------
        A&B = 0000 1100
        A|B = 0011 1101
        A^B = 0011 0001//相同为0，不同为1
        ~B = 1111 0010

        2 * 8 = 16  2*2*2*2
        效率极高！！！！！！
        << 左移*2   >>右移/2
        0000 0000  0
        0000 0001  1
        0000 0010  2
        0000 0011  3
        0000 0100  4
        0000 1000  8
        0001 0000  16
         */
        System.out.println(2<<3);//16
    }
}

 

package Operator;

public class Demo07 {
    public static void main(String[] args) {
        int a = 10;
        int b =20;
        a += b;//a = a + b
        System.out.println(a);//30
        a -= b;//a = a - b
        System.out.println(a);//10
        System.out.println("------------------------------------");
        //字符串连接符，遵循前面的类型
        System.out.println(a + b);//30
        System.out.println(a + b+"");//30
        System.out.println(""+ a + b);//1020
    }
}

 

package Operator;
//三元运算符
public class Demo08 {
    public static void main(String[] args) {
        // x ? y : z
        //如果x 为true,则结果为y,否则结果为z
        int score = 60;
        String type = score < 60 ? "不及格！" : "及格!";
        System.out.println(type);//及格！
       // if ()
        
    }
}