How do I print an array in Java's jdb debugger?

Question

How do I print out the values of the byte array all at once? I seem to recall I could specify a memory range in gdb. Is similar functionality is available in jdb?

I have a Java byte array:

byte [] decompressed = new byte[OUTPUT_FILE_IO_BUFFER_SIZE];

which I populate from a String:

System.arraycopy(decompressedString.getBytes(), 0, decompressed, 0, 
                         decompressedString.length());

In jdb, I want to print the contents of the byte array. I tried

main[1] print decompressed

which returns:

 decompressed = instance of byte[7] (id=342)

iokevins · Accepted Answer · 2009-12-06 03:09:47Z

6

One solution:

dump decompressed

This dumps the byte values! :)

answered Dec 6, 2009 at 3:09

iokevins

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ashgromnies Over a year ago

it's printing them as signed integers -- is there any way to get it to print hex values? Local variables: prefix = instance of byte[16] (id=2384) Main Thread[1] dump prefix prefix = { -118, -113, -73, -125, 13, -42, -63, 87, -10, 54, -122, 57, -63, 3, 81, 116 }

Yas Ikeda · Accepted Answer · 2024-11-18 10:10:01Z

0

It is a bit lengthy, but it can display all the elements in a line.

print java.util.Arrays.toString(decompressed)

Even if the array was a boxed-type array (like Byte[]), Arrays.asList could also provide the same. It is slightly shorter.

print java.util.Arrays.asList(decompressed)

edited Nov 18, 2024 at 10:10

answered Nov 16, 2024 at 0:49

Yas Ikeda

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2 Comments

user85421 Over a year ago

Arrays.asList() will not work - It does not take primitives as variable-arity argument - in posted example it will create a List with one single element: the array itself. So the output will be something like [[B@12345678]!

Yas Ikeda Over a year ago

@user85421, you're right. Arrays.asList does not work. I confused with its behaviour for byte[] and Byte[]. In my personal issue, the target array was of boxed-type, and it made Arrays.asList return a List<Byte> instance, then print command outputs the same result as Array.toString. On the other hand, Arrays.asList returns a List<byte[]> instance when byte[] is given, then print command outputs the result you mentioned. I updated my answer.

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