Java直接运行源代码文件，不会产生HelloWorld.class第二种方法：把模块放在D盘下，然后导入

第三种方法：新建一个模块，然后把内容复制过去

byte l = 12;
short m =l;
System.out.println(m);
char n ='a';
int reason = m+n;
System.out.println(reason);

整数相除想得到小数：

System.out.println(5/2);
System.out.println(5.0/2);
int a1 = 5;
int b1 = 2;
System.out.println(1.0*a1/b1);

System.out.println("chiikawa"+a2+'a');//chiikawa10a
System.out.println(a2+'a'+"chiikawa");//107chiikawa

        int c1 = 10;
        int rs = c1++;//先用c1的值计算rs，然后再加1
        System.out.println(rs);//10
        System.out.println(c1);//11
        int d1 = 10;
        int rd = ++d1;//先加1，然后用d1的值计算rd
        System.out.println(rd);//11
        System.out.println(d1);//11

 

        byte x = 10;
        byte y =30;
        //x = x+y;//编译错误，类型不匹配
        x = (byte)(x+y);
        x+=y;//等价于x = (byte)(x+y);
        System.out.println(x);//40

        int a =99;
        int b = 67;
        int max = a>b?a:b;
        System.out.println(max);
        int i = 10;
        int j = 45;
        int k = 34;
        int temp =i>j? i:j;
        int max2 = temp>k?temp:k;
        System.out.println(max2);