Java基础语法之基本运算符

9、基本运算符

• 算数运算符：+，-，*，/，%，++，--

• 赋值运算符：=

• 关系运算符：>, <,>=,<=,==,!=,instanceof

• 逻辑运算符：&&，||，！

• 位运算符：&，|，^,~,>>,<<,>>>(了解！！！)

• 条件运算符：？，：

• 扩展赋值运算符：+=，-=，*=，/=

package operator;

public class Demo01 {
    public static void main(String[] args) {
        //二元运算符
        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);
    }
}

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

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
        // 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);
    }
}

package operator;

public class Demo04 {
    public static void main(String[] args) {
        //++ --  自增，自减  一元运算符
        int a = 3;
        int b = a++; //执行完这行代码后，先给b赋值，再自增
        //a++  a = a + 1
        System.out.println(a);//4
        //++a  a = a + 1
        int c = ++a; //执行完这行代码前，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  2*2*2 = 8  很多运算，我们会使用一些工具类来操作！
        double pow = Math.pow(2, 3);
        System.out.println(pow);
    }
}

package operator;

//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，结果才为真。
        System.out.println("a || b:"+(a || b)); //逻辑与运算：两个变量有一个为真，则结果为真。
        System.out.println("!(a && b):"+!(a && b)); //如果是真则为假；如果是假则为真。
        //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
        ~B = 1111 0010

        2*8  2*2*2*2
        效率极高！！！
        << *2
        >> /2
         */
        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
        a-=b; //a = a - b
        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); //1020
        System.out.println(a+b+""); //30

    }
}

package operator;

//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);//不及格
    }
}