operator---8个Demo

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);
        System.out.println(a-b);
        System.out.println(a*b);
        System.out.println(a/(double)b);


    }
}

public class Demo02 {
    public static void main(String[] args) {
        long a = 1231564613132L;
        int b = 123;
        short c = 10;
        byte d = 8;

        System.out.println(a+b+c+d);//Long
        System.out.println(b+c+d);//int
        System.out.println(c+d);//int
    }
}

public class Demo03 {
    public static void main(String[] args) {
        //关系运算符返回结果：正确，错误   布尔值
        //if

        int a = 10;
        int b = 20;
        int c = 21;

        //取余，模运算
        System.out.println(c%a);//c / a     21 / 10 = 2 ... 1

        System.out.println(a>b);
        System.out.println(a<b);
        System.out.println(a==b);
        System.out.println(a!=b);
    }
}

public class Demo04 {
    public static void main(String[] args) {
        //++ --     自增  自减  一元运算符
        int a = 3;

        int b = a++;//执行完这段代码后，先给b赋值，再自增
        // a = a + 1;
        System.out.println(a);
        // a = a + 1;
        int c = ++a;//执行完这段代码前，先自增,再给b赋值

        System.out.println(a);
        System.out.println(b);
        System.out.println(c);

        //幂运算  2^3  2*2*2 = 8   很多运算，我们会使用工具类来操作!
        double pow = Math.pow(3,2);
        System.out.println(pow);
    }
}

//逻辑运算符
public class Demo05 {
    public static void main(String[] args) {
        // 与(and)    或(or)   非(取反)
        boolean a = true;
        boolean b = false;

        System.out.println("a && b："+(a && b));//逻辑与运算，两个变量都为真，结果才为true
        System.out.println("a || b："+(a || b));//逻辑与运算，两个变量有一个为真，则结果才为true
        System.out.println("!(a && b)："+!(a && b));//如果是真，则变为假，如果是假，则变为真

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

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
        ~B  = 1111 0010

        2*8 = 16    2*2*2*2
        效率极高！！！
        <<  *2
        >>  /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);
    }
}

public class Demo07 {
    public static void main(String[] args) {
        int a = 10;
        int b = 20;

        a+=b;//a = a+b
        a-=b;//a = a-b

        System.out.println(a);

        //字符串连接符    + ,String
        System.out.println(""+a+b);

        System.out.println(a+b+"");

    }
}

//三元运算符
public class Demo08 {
    public static void main(String[] args) {
        // x ? y : z
        //如果x==true，则结果为y，否则结果为z

        int score = 50;
        String type = score < 60 ?"不及格":"及格";//必须掌握
        // if
        System.out.println(type);
    }
}