3
int row = 100000;
int col = 18;
Object[][] objectArray = new Object[row][1];
int[][] intArray = new int[row][1];
System.out.println("Size of objectArray = " + net.sourceforge.sizeof.SizeOf.deepSizeOf(objectArray) + " bytes");
System.out.println("Size of intArray = " + net.sourceforge.sizeof.SizeOf.deepSizeOf(intArray) + " bytes");
Object[][] objectMatrix = new Object[row][col];
int[][] intMatrix = new int[row][col];
System.out.println("Size of objectMatrix = " + net.sourceforge.sizeof.SizeOf.deepSizeOf(objectMatrix) + " bytes");
System.out.println("Size of intMatrix = " + net.sourceforge.sizeof.SizeOf.deepSizeOf(intMatrix) + " bytes");
相关输出
Size of objectArray = 4000024 bytes
Size of intArray = 4000024 bytes
Size of objectMatrix = 17600024 bytes
Size of intMatrix = 10400024 bytes
如果不是1D(数COLS = 1),I具有2D(数1),对象矩阵需要更多的空间。
有人可以解释原因吗?
编辑:添加另一种情况下只用一个行
int row = 1;
int col = 2;
Object[][] objectArray = new Object[row][1];
int[][] intArray = new int[row][1];
System.out.println("Size of objectArray = " + net.sourceforge.sizeof.SizeOf.deepSizeOf(objectArray) + " bytes");
System.out.println("Size of intArray = " + net.sourceforge.sizeof.SizeOf.deepSizeOf(intArray) + " bytes");
Object[][] objectMatrix = new Object[row][col];
int[][] intMatrix = new int[row][col];
System.out.println("Size of objectMatrix = " + net.sourceforge.sizeof.SizeOf.deepSizeOf(objectMatrix) + " bytes");
System.out.println("Size of intMatrix = " + net.sourceforge.sizeof.SizeOf.deepSizeOf(intMatrix) + " bytes");
输出
Size of objectArray = 64 bytes
Size of intArray = 64 bytes
Size of objectMatrix = 72 bytes
Size of intMatrix = 64 bytes
我想也许一个对象数组需要更多的空间。 (不知道为什么会这样,但这是可能的,这取决于内部实现。) – 2012-04-13 18:02:09
(当然,在完整的64位Java实现中,指针是整数的两倍)。 – 2012-04-13 18:03:07
(我不知道如何deepSizeOf在内部工作,但如果它以某种方式查看分配,则不能保证两个相同的对象占用相同的大小分配。) – 2012-04-13 18:05:34