运算符

运算符

加减乘除

package operator;

public class D01 {
    public static void main(String[] args) {
        int a =10;
        int b =20;
        int c =25;
        int d =30;
        System.out.println(a+b);
        System.out.println(a-b);
        System.out.println(a*b);
        System.out.println((double)a/b);//0.5
    }
}

package operator;

public class D02 {
    public static void main(String[] args) {
        long a =12300000000L;
        int b =123;
        short c =10;
        byte d =8;
        System.out.println(a+b+c);//long
        System.out.println(d+b+c);//int
        System.out.println(d+c);//int
    }
}

package operator;

public class D03 {
    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 = 21;
        System.out.println(a>b);//false
        System.out.println(a<b);//true
        System.out.println(a==b);//false
        System.out.println(a!=b);//true
        //取余，模运算
        System.out.println(c%a);//c/a=21/10=2..............1 取余数1

    }
}

++ -- 和幂运算

package operator;

public class D04 {
    public static void main(String[] args) {
        // ++ -- 自增 ，自减   一元运算符
        int a=3;
        //System.out.println(a);=3
        int b =a++;//a++   a=a+1执行完这行代码后，先给b赋值,再自增
        //System.out.println(a);=4
        int c = ++a;//++a   a=a+1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);
        System.out.println(c);
        //幂运算 2^3 2*2*2=8 工具Math     很多运算使用工具类来操作！
        double pow =Math.pow(2,3);
        System.out.println(pow);
    }
}

与或非

package operator;

public class D05 {
    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));//逻辑运算，两个变量都为真，结果才为ture
        System.out.println("a || b:"+(a||b));//逻辑运算，两个变量有一个为真，结果才为ture
        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
        System.out.println("=========================================================");
        int c=5;
        boolean d=(c<4)&&(c++<4);
        System.out.println(d);
        System.out.println(c);
    }
}

<<左移 >>右移

package operator;

public class D06 {
    public static void main(String[] args) {
        /**
         * A=0011 1100
         * B=0000 1101
         * -----------------------------------------------
         * A&B= 0000 1100都是1为1
         * A|B= 0011 1101都是0为0
         * A^B= 0011 0001相同为0，不同为1
         * ~B= 1111 0010相反
         *--------------------------------------------------
         * <<左移    *2
         * >>右移    /2
         * */
        System.out.println(2<<3);
        System.out.println(2>>3);
    }
}

字符串连接

package operator;

public class D07 {
    public static void main(String[] args) {
        int a=10;
        int b =20;
        a+=b;//a=a+b
        //30
        a-=b;//a=a-b
        //10
        System.out.println(a);
        //字符串连接符   +  ,String
        System.out.println(""+a+b);
        System.out.println(a+b+"");
    }
}

？：

package operator;

public class D08 {
    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 age =18;
        String type = age>=18?"成年":"未成年";
        System.out.println(type);
    }
}