在Java中进行声明后分配给数组的字节数 [英] Number of bytes allocated to an array after it's declaration in java

问题描述

在Java中，声明数组后如何检查分配给数组的字节数?例如:

In Java, how the check number of bytes allocated to an array after it's declaration? For example:

int[] a = new int[10]; 

数组'a'被分配4 * 10字节，因为int的大小为4字节，并且有10个整数元素.有非手动的方式吗?

Array 'a' is allocated 4*10 bytes since the size of int is 4 bytes and there are 10 integer elements. Is there a non-manual way of doing this?

推荐答案

实际上 int [10] 的大小为56个字节或更多(取决于JVM).

Actually the size of int[10] is 56 bytes or more (depending on your JVM).

• 10 * 4 = 40个字节(十个整数)
• 4个字节来存储数组长度
Java对象
• 8个字节
• 4个字节以使对象的大小为8(对齐)的倍数.

但这全部取决于您的操作系统的JVM和内存体系结构. java.lang.instrumentation.Instrumentation 提供了一种计算对象大小的方法，如此答案.

But this all depends on the JVM and memory architecture of your operating system. java.lang.instrumentation.Instrumentation provides a way to calculate sizes of an object, as explained in this answer.

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