What is the maximum size of a `String` object in Java?

Question

A simple question: What is the maximum size (in bytes or characters) of a String object in Java?

Some background info: I want to build a SQL statement (INSERT INTO tbl VALUES (...), (...), ...) and I don't want to exceed the size of the object.

score 7 · Accepted Answer · answered Jul 11 '13 at 22:18

7

Strings contain an array of chars, so I think you can have at most 2^31 - 1 characters in a Java String. This is the value of Integer.MAX_VALUE.

Any String larger than that, and you can't even index all of the elements.

answered Jul 11 '13 at 22:18

jh314

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Assuming you have sufficient memory available. – Jul 11 '13 at 22:18
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That one String would be roughly 4GB if I did the math correctly. – Jul 11 '13 at 22:21

score 3 · Answer 2 · answered Jul 11 '13 at 22:21

from the source code

class String implements java.io.Serializable {
    private char value[]; // 4 bytes + 12 bytes of array header
    private int offset; // 4 bytes
    private int count; // 4 bytes
}

what ever the value of Integer.MAX_VALUE is (which on most systems will be 2^31 -1)

this requires 4GB of memory though so its a very large amount (java uses 16 bit unicode)

so the minimum of Integer.MAX_VALUE and the available memory

score 2 · Answer 3 · edited May 23 '17 at 10:28

2

It sounds like you want to insert many rows. Use a PreparedStatement and batch parameters. https://stackoverflow.com/a/3786127/1172714.

Please note that assembling a SQL statement as a String is a dangerous practice. Instead use a prepared statement http://docs.oracle.com/javase/tutorial/jdbc/basics/prepared.html

edited May 23 '17 at 10:28

Community

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answered Jul 11 '13 at 22:39

dsh

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Thank you. I know it can be dangerous, but this specific program is for my personal use, and I can take the luxury of being "not so formal" ;-) – Barranka Jul 11 '13 at 22:40

score 1 · Answer 4 · answered Jul 11 '13 at 22:20

1

Theoretically it could be Integer.MAX_VALUE chars long.

answered Jul 11 '13 at 22:20

Harald K

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What is the maximum size of a `String` object in Java?

4 Answers4