运算符

package operator;

public class Demo01 {
    public static void main(String[] args) {
        //二元运算符 加减乘除
        //ctrl + d :复制当前行到下一行
        int a = 10;
        int b = 20;
        int c = 25;
        int d = 26;

        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如果里面有LONG就是long类型
        //double同理
    }
}

    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(c%a);//c /a   21 /10 = 2....1(取余,也叫模运算)
        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++;//执行完这行代码后,先给b赋值.在自增
        //a++  a = a + 1
        System.out.println(a);
        int c = ++a;//执行完这行代码前,先自增,在给b赋值
        //a++  a = a + 1
        System.out.println(b);
        System.out.println(c);
        //幂运算 2^3  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;

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,则结果为true
        System.out.println("! (a && b):"+!(a&&b));//如果是真,则变为假.若果是假则变为真
        //短路运算
        int c = 5;
        boolean d = (c<4)&&(c++<4);
        System.out.println(d);
        System.out.println(c);
    }

}

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

package operator;

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

        int score = 80;
        String type = score <60 ?"不及格":"及格";//必须掌握
        //if
        System.out.println(type);
    }
}