java - 在单个二维数组中存储多种数据类型

Question

我需要在二维数组中存储多种数据类型(主要是 int 或 string)。使用 Object[][] 确实可以解决问题。但这是一个好方法吗？

Object[][] 数组如何保留堆空间？我的意思是，按照哪种数据类型？是否会导致资源浪费？

我试图做这样的事情:-

Object[][] dataToBeWritten={ {"帕米",34,45},
{"罗恩","x",""},
{"蜘蛛","x",""}
};

编辑:如果存在的话，您也可以建议任何更好的替代方案..

Answer 1

参见How to calculate the memory usage of a Java array和 Memory usage of Java objects: general guide .

For example, let's consider a 10x10 int array. Firstly, the "outer" array has its 12-byte object header followed by space for the 10 elements. Those elements are object references to the 10 arrays making up the rows. That comes to 12+4*10=52 bytes, which must then be rounded up to the next multiple of 8, giving 56. Then, each of the 10 rows has its own 12-byte object header, 4*10=40 bytes for the actual row of ints, and again, 4 bytes of padding to bring the total for that row to a multiple of 8. So in total, that gives 11*56=616 bytes. That's a bit bigger than if you'd just counted on 10*10*4=400 bytes for the hundred "raw" ints themselves.

我认为这仅适用于 Hotspot。对任何对象的引用只是链接整数，每个 4 字节，无论实际对象如何，或者对象是否为 null。不过，对象本身的备用要求是一个完全不同的故事，因为在创建数组时没有保留空间或类似的东西。