deamo00

package OPERATOR;

public class Deamo01 {
    public static void main(String[] args) {
        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/b);
    }

    public static class deamo1 {
        public static void main(String[] args) {
            System.out.println("Hello\tWorld");
            char c1 ='你';
            System.out.println((int)c1);
            char c2 ='好';
            System.out.println((int) c2);
            System.out.println((char) c1);
            System.out.println((char) c2);
            int num =809651316;
            if (num!=809651316) {
                System.out.println("成功登录");
            } else{
                System.out.println("登录失败");
            }
            System.out.println((int)num);

        }

    }

    public static class deamo2 {
        public static void main(String[] args) {
            int i =128;
            byte b =(byte)i;
            System.out.println(i);
            System.out.println(b);
            //强制转换（变量名称)
            System.out.println("-------------------------------------------------");
            byte b1 =1;
            int  i1 =b1;
            System.out.println(b1);
            System.out.println(i1);
            //非强制转换不需要（）
            System.out.println("-------------------------------------------------");
            System.out.println((int)27.89);     //27
            System.out.println((int)-45.999);   //-45
            //转换时的精度会变
            System.out.println("-------------------------------------------------");
            char c1 ='a';
            int  i2 =c1+1;
            System.out.println(i2);
            System.out.println((char) i2);
            //变换字母
            System.out.println("-------------------------------------------------");
            int money =10_0000_0000;
            System.out.println(money);//输出的为1000000000
            int money1 =10-0000-0000;
            System.out.println(money1);//输出的为10
            //在处理较大的数据时可以用下划线_来进行分割
            System.out.println("-------------------------------------------------");
            int money2 =10_0000_0000;
            int year   =20;

            int total =money2*year;
            System.out.println(total);//输出为-1474836480（错误）

            long total1 =money2*(long)(year);
            System.out.println(total1);//输出为20000000000(正确)

            long total2 =(long)(money2)*year;
            System.out.println(total2);//输出为20000000000(正确)

            //如果在输出较大的乘法时，要先进行转换(转换其中一个即可)
            System.out.println("-------------------------------------------------");



        }
    }

    public static class deamo3 {
        //属性；变量




        //实例变量：从属于对象  如果没有设定初始值，则按照默认值进行
        //布尔值默认为false
        /**除了基本类型其他的初始值都为null(空白)
         * 基本类型（byte short int long char float double boolean）
         */
        String name;
        byte age1;
        short age2;
        int age3;
        long age4;
        char age5;
        float age6;
        double age7;
        boolean age8;

        //类变量
        static double salary =5000;








        //main 方法
        public static void main(String[] args) {
            //局部变量  必须声明和初始化数值
            int i =10;
            System.out.println(i);





            //变量类型    变量名字= OPERATOR.Deamo01.deamo3
            deamo3 deamo3 = new deamo3();
            System.out.println(deamo3.age1);  //输出的为0
            System.out.println(deamo3.age2);  //输出的为0
            System.out.println(deamo3.age3);  //输出的为0
            System.out.println(deamo3.age4);  //输出的为0
            System.out.println(deamo3.age5);  //输出的为0
            System.out.println(deamo3.age6);  //输出的为0.0
            System.out.println(deamo3.age7);  //输出的为0.0
            System.out.println(deamo3.age8);  //输出的为false
            System.out.println(deamo3.name);  //输出的为null



            //类变量 static
            System.out.println(salary);


        }
        //其他方法
        public  void add(){




        }

        public static class jbav4 {
        }
    }
}