Length of a String

[Varun Narula]

Is there some way to have more than the 65k chars a String can hold?

[eammon bannon]

Strings can hold a lot more than 65k characters - (there's an urban myth that String literals that are restricted to max 64k). A String object's length is only restricted by the value of Integer.MAX_VALUE (since that will be the biggest value that String.length() can return) - which is 2147483647. So a String can hold 2147483647 chars. Whether you should ever create a String which will use that much memory however is entirely another matter.
[ March 19, 2004: Message edited by: eammon bannon ]

[Mani Ram]

Originally posted by eammon bannon:
Strings can hold a lot more than 65k characters - (there's an urban myth that String literals that are restricted to max 64k).
[ March 19, 2004: Message edited by: eammon bannon ]

Mmmm.....try this code

String s = "****************..."; //Total of 65536 '*'

You will get ClassFormatError (Illegal constant pool type) when the class is loaded.
But this will work fine,

String s = "****************..."; //Total of 65535 '*'. (One less)
s += "*"; // Now s has 65536 '*'s

Got it?

[eammon bannon]

I stand corrected Mani. That will teach me for believing what I read without trying it myself. Oh well. Still, its a pretty daft thing to want do in your code.

[Eddie Vanda]

I tried to see how many times I could double the length of a string and I got to a count of 23 with about 8 Meg before the operation failed with an out of memory error out of heap space which crashed the program (gracefully).

[Tim West]

An addendum to Eddie's post (had to try it for myself just to check) - the following worked fine.

        String s = "*";
        
        for (int i = 1; i < 18; i++) {
            s = s + s;
            System.out.println("Length is: " + s.length() + ".");
            // System.out.println(s);
        }
        
        System.out.println(s.charAt(100000));

If you uncomment the println(s) line, it will work still, but you get a whole lot of *s on your output
Mine also bombs out at 2^23.
Looks like it's a bug in the parser - can't have string literals more than 65536 chars?
--Tim

[Geoffrey Falk]

What JDK version, patchlevel and platform are you using?
Geoffrey

[Tim West]

I'm not sure if that question was directed at me (it probably wasn't), but here goes...
The (run-time) error I get when a declaring a String literal with exactly 65536 '*'s (ie, String s = "***..." is (from a class 'DateTrial', I was messing around with dates earlier...):

java.lang.ClassFormatError: DateTrial (Illegal constant pool type)
        at java.lang.ClassLoader.defineClass0(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:502)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:123)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:250)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:54)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:193)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:186)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:299)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:265)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:255)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:315)
Exception in thread "main"

My System properties are (System.getProperties().list(System.out); - hope this has enough info for you)

java.runtime.name=Java(TM) 2 Runtime Environment, Stand...
sun.boot.library.path=C:\j2sdk1.4.1_03\jre\bin
java.vm.version=1.4.1_03-b02
java.vm.vendor=Sun Microsystems Inc.
java.vendor.url=http://java.sun.com/
path.separator=;
java.vm.name=Java HotSpot(TM) Client VM
file.encoding.pkg=sun.io
user.country=AU
sun.os.patch.level=Service Pack 2
java.vm.specification.name=Java Virtual Machine Specification
user.dir=C:\Sun\studio5_se\bin
java.runtime.version=1.4.1_03-b02
java.awt.graphicsenv=sun.awt.Win32GraphicsEnvironment
java.endorsed.dirs=C:\j2sdk1.4.1_03\jre\lib\endorsed
os.arch=x86
java.io.tmpdir=C:\DOCUME~1\timothyw\LOCALS~1\Temp\
line.separator=
java.vm.specification.vendor=Sun Microsystems Inc.
user.variant=
os.name=Windows 2000
sun.java2d.fontpath=
java.library.path=C:\j2sdk1.4.1_03\jre\bin;.;C:\WINNT\S...
java.specification.name=Java Platform API Specification
java.class.version=48.0
java.util.prefs.PreferencesFactory=java.util.prefs.WindowsPreferencesFac...
os.version=5.0
user.home=C:\Documents and Settings\timothyw
user.timezone=
java.awt.printerjob=sun.awt.windows.WPrinterJob
file.encoding=Cp1252
java.specification.version=1.4
user.name=timothyw
java.class.path=C:\Documents and Settings\timothyw\st...
java.vm.specification.version=1.0
sun.arch.data.model=32
java.home=C:\j2sdk1.4.1_03\jre
java.specification.vendor=Sun Microsystems Inc.
user.language=en
awt.toolkit=sun.awt.windows.WToolkit
java.vm.info=mixed mode
java.version=1.4.1_03
java.ext.dirs=C:\j2sdk1.4.1_03\jre\lib\ext
sun.boot.class.path=C:\j2sdk1.4.1_03\jre\lib\rt.jar;C:\j2...
java.vendor=Sun Microsystems Inc.
file.separator=\
java.vendor.url.bug=http://java.sun.com/cgi-bin/bugreport...
sun.cpu.endian=little
sun.io.unicode.encoding=UnicodeLittle
sun.cpu.isalist=pentium i486 i386

Incidentally, I was being daft earlier - it's not a bug in javac since it's a runtime error. I didn't notice as I was using compile/run in my IDE...
I'd post the code that produces the error, but it wouldn't be the prettiest of posts - one whole load of *s.
Cheers,

--Tim