Why does this exceed the 65535 byte limit in Java constructors and static initializers?

Disclaimer: I realize that I can generate this at Java runtime. When testing some code, I need a very special case I found a different way, so now it's just a curiosity than any practical curiosity

I've tried to take the following as a static field, as an instance field, and initialize it directly in the constructor Every time eclipse informs me that "the code of the constructor testdata () exceeds the 65535 byte limit" or "the code of the static initializer exceeds the 65535 byte limit"

There are 10000 integers If each int is 4 bytes (32 bits), wouldn't it be 40000 bytes? In addition to just building the data of the array, is there any more overhead of 250000 bytes?

This data is generated using this small Python:

#!/usr/bin/python

import random;
print "public final int[] RANDOM_INTEGERS = new int[] {";
for i in range(1,10000):
    print str(int(random.uniform(0,0x7fffffff))) + ",";
print "};";

This is a small sample:

public final int[] RANDOM_INTEGERS = new int[] {
    963056418,460816633,1426956928,1836901854,334443802,721185237,488810483,1734703787,1858674527,112552804,1467830977,1533524842,1140643114,1452361499,716999590,652029167,1448309605,1111915190,1032718128,1194366355,112834025,419247979,944166634,205228045,1920916263,1102820742,1504720637,757008315,67604636,1686232265,597601176,1090143513,205960256,1611222388,1997832237,1429883982,1693885243,1987916675,159802771,1092244159,1224816153,1675311441,1873372604,1787757434,1347615328,1868311855,1401477617,508641277,1352501377,1442984254,1468392589,1059757519,1898445041,1368044543,513517087,99625132,1291863875,654253390,169170318,2117466849,1711924068,564675178,208741732,1095240821,1993892374,87422510,1651783681,1536657700,1039420228,674134447,1083424612,2137469237,1294104182,964677542,1506442822,1521039575,64073383,929517073,206993014,466196357,1139633501,1692533218,1934476545,2066226407,550646675,624977767,1494512072,1230119126,1956454185,1321128794,2099617717,//.... to 10,0000 instances

Solution

The following is the bytecode for initializing the array with {1000001100002100003}:

5  iconst_3
 6  newarray int [10]
 8  dup
 9  iconst_0
10  ldc <Integer 1000001> [12]
12  iastore
13  dup
14  iconst_1
15  ldc <Integer 1000002> [13]
17  iastore
18  dup
19  iconst_2
20  ldc <Integer 1000003> [14]
22  iastore
23  putfield net.jstuber.test.TestArrayInitializingConstructor.data : int[] [15]

So for this small array, each element needs 5 bytes of Java bytecode For larger arrays, the array index and the index in the constant pool will use 3 bytes for most elements, resulting in 8 bytes per array element Therefore, for 10000 elements, you have to expect about 80 KB of bytecode

The code for initializing a large array with a 16 bit index is as follows:

2016  dup
2017  sipush 298
2020  ldc_w <Integer 100298> [310]
2023  iastore
2024  dup
2025  sipush 299
2028  ldc_w <Integer 100299> [311]