public class demo05 {
    public static void main(String[] args) {
        //操作数量比较大的数值时 注意溢出问题
        //JDK7新特性 数字之间可以用下划线 _ 分割 并且不会被输出
        int money = 10_0000_0000;
        System.out.println(money);
        System.out.println("==============================");
        int years = 20;
        int total = money*years;
        long total2 = money*years;
        System.out.println(total);//-1474836480 内存溢出
        System.out.println(total2);//默认是int 转换之前已经内存溢出
        System.out.println("==============================");
        long total3 = (long)money*years;
        System.out.println(total3);//20000000000 先把一个数值强制转换为long 计算是就会把整体都按long的级别来运算
    }
}