ADDITIONAL SYSTEM INFORMATION :
openjdk 25-ea 2025-09-16
OpenJDK Runtime Environment (build 25-ea+19-2255)
OpenJDK 64-Bit Server VM (build 25-ea+19-2255, mixed mode, sharing)

Ubuntu 24.04 in WSL (Windows 11)

However, Java 21 (Temurin) + Windows 11 can reproduce this bug too.

openjdk 21.0.3 2024-04-16 LTS
OpenJDK Runtime Environment Temurin-21.0.3+9 (build 21.0.3+9-LTS)
OpenJDK 64-Bit Server VM Temurin-21.0.3+9 (build 21.0.3+9-LTS, mixed mode, sharing)

A DESCRIPTION OF THE PROBLEM :
Print functions in IO, System.console(), or System.console().writer() like IO.println throws an NegativeArraySizeException when a string with a specific length is passed only in JShell.

The offending lengths are e.g. 128-255, 384-511, and 640-767, where ((length & 0x80) == 0x80). String arguments with other lengths are output without Exceptions (as are as long as they are not affected by JDK-8354910).

The culprit is thought to be the same as that of JDK-8354910; https://github.com/openjdk/jdk/blob/a2dc9c71e47a1cdf70ab351c557a5f1835eb5f4a/src/jdk.jshell/share/classes/jdk/jshell/execution/impl/ConsoleImpl.java#L398 doesn't handle negative argument values derived from a (negative) byte-type value even though OutputStream.write(int) stipulates that "The byte to be written is the eight low-order bits of the argument b. The 24 high-order bits of b are ignored." in https://download.java.net/java/early_access/loom/docs/api/java.base/java/io/OutputStream.html#write(int).

The `buffer` array doesn't assume that it stores negative values according to https://github.com/openjdk/jdk/blob/a2dc9c71e47a1cdf70ab351c557a5f1835eb5f4a/src/jdk.jshell/share/classes/jdk/jshell/execution/impl/ConsoleImpl.java#L470-L480, but actually it does due to https://github.com/openjdk/jdk/blob/a2dc9c71e47a1cdf70ab351c557a5f1835eb5f4a/src/jdk.jshell/share/classes/jdk/jshell/execution/impl/ConsoleImpl.java#L398.

`& 0x80` must have been added at https://github.com/openjdk/jdk/blob/a2dc9c71e47a1cdf70ab351c557a5f1835eb5f4a/src/jdk.jshell/share/classes/jdk/jshell/execution/impl/ConsoleImpl.java#L398.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Run jshell --enable-preview (--enable-preview is unnecessary when you test only System.console().printf or methods of System.console().writer())
2. Execute either of the following methods with an argument as a string with a length of e.g. 128-255, 384-511, or 640-767 there. You can utilize String.repeat to generate one easily, e.g. "a".repeat(128).

Offending methods (the trailing * means that it requires --enable-preview):

- IO.print *
- IO.println *
- System.console().print *
- System.console().println *
- System.console().printf
- System.console().writer().write
- System.console().writer().print
- System.console().writer().println
- System.console().writer().printf

Note: works properly outside of JShell (e.g. java command with a .java source code) like JDK-8354910

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
jshell> IO.println("a".repeat(128))
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

jshell> IO.print("a".repeat(128))
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
jshell> System.console().print("a".repeat(128))
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa$1 ==> java.io.ProxyingConsole@4459eb14

jshell> System.console().println("a".repeat(128))
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
$2 ==> java.io.ProxyingConsole@4459eb14

jshell> System.console().printf("a".repeat(128))
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa$3 ==> java.io.ProxyingConsole@4459eb14

jshell> System.console().writer().print("a".repeat(128))
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
jshell> System.console().writer().println("a".repeat(128))
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

jshell> System.console().writer().printf("a".repeat(128))
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
jshell> System.console().writer().write("a".repeat(128))
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
jshell> IO.println("a".repeat(255))
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

jshell> IO.println("a".repeat(384))
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

jshell> IO.println("a".repeat(511))
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa


ACTUAL -
jshell> IO.println("a".repeat(128))
Exception in thread "output reader" java.lang.NegativeArraySizeException: -128
        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.readCharsOrNull(ConsoleImpl.java:486)
        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.write(ConsoleImpl.java:402)
        at java.base/java.io.OutputStream.write(OutputStream.java:167)
        at java.base/java.io.OutputStream.write(OutputStream.java:124)
        at jdk.jshell/jdk.jshell.execution.DemultiplexInput.run(DemultiplexInput.java:74)
| State engine terminated.
| Restore definitions with: /reload -restore

jshell> IO.print("a".repeat(128))
Exception in thread "output reader" java.lang.NegativeArraySizeException: -128
        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.readCharsOrNull(ConsoleImpl.java:486)
        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.write(ConsoleImpl.java:402)
        at java.base/java.io.OutputStream.write(OutputStream.java:167)
        at java.base/java.io.OutputStream.write(OutputStream.java:124)
        at jdk.jshell/jdk.jshell.execution.DemultiplexInput.run(DemultiplexInput.java:74)
| State engine terminated.
| Restore definitions with: /reload -restore

jshell> System.console().print("a".repeat(128))
Exception in thread "output reader" java.lang.NegativeArraySizeException: -128
        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.readCharsOrNull(ConsoleImpl.java:486)
        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.write(ConsoleImpl.java:402)
        at java.base/java.io.OutputStream.write(OutputStream.java:167)
        at java.base/java.io.OutputStream.write(OutputStream.java:124)
        at jdk.jshell/jdk.jshell.execution.DemultiplexInput.run(DemultiplexInput.java:74)
| State engine terminated.
| Restore definitions with: /reload -restore
$1 ==>

jshell> System.console().println("a".repeat(128))
Exception in thread "output reader" java.lang.NegativeArraySizeException: -128
        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.readCharsOrNull(ConsoleImpl.java:486)
| State engine terminated. at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.write(ConsoleImpl.java:402)

        at java.base/java.io.OutputStream.write(OutputStream.java:167)
        at java.base/java.io.OutputStream.write(OutputStream.java:124)
| Restore definitions with: /reload -restore
        at jdk.jshell/jdk.jshell.execution.DemultiplexInput.run(DemultiplexInput.java:74)
$1 ==>

jshell> System.console().printf("a".repeat(128))
Exception in thread "output reader" java.lang.NegativeArraySizeException: -128
        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.readCharsOrNull(ConsoleImpl.java:486)
        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.write(ConsoleImpl.java:402)
        at java.base/java.io.OutputStream.write(OutputStream.java:167)
        at java.base/java.io.OutputStream.write(OutputStream.java:124)
| State engine terminated. at jdk.jshell/jdk.jshell.execution.DemultiplexInput.run(DemultiplexInput.java:74)

| Restore definitions with: /reload -restore
$1 ==>

jshell> System.console().writer().print("a".repeat(128))
Exception in thread "output reader" java.lang.NegativeArraySizeException: -128
| State engine terminated.
        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.readCharsOrNull(ConsoleImpl.java:486)
| Restore definitions with: /reload -restore
        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.write(ConsoleImpl.java:402)
        at java.base/java.io.OutputStream.write(OutputStream.java:167)
        at java.base/java.io.OutputStream.write(OutputStream.java:124)
        at jdk.jshell/jdk.jshell.execution.DemultiplexInput.run(DemultiplexInput.java:74)

jshell> System.console().writer().println("a".repeat(128))
Exception in thread "output reader" java.lang.NegativeArraySizeException: -128
        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.readCharsOrNull(ConsoleImpl.java:486)
        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.write(ConsoleImpl.java:402)
| State engine terminated. at java.base/java.io.OutputStream.write(OutputStream.java:167)

        at java.base/java.io.OutputStream.write(OutputStream.java:124)
| Restore definitions with: /reload -restore at jdk.jshell/jdk.jshell.execution.DemultiplexInput.run(DemultiplexInput.java:74)


jshell> System.console().writer().printf("a".repeat(128))
Exception in thread "output reader" java.lang.NegativeArraySizeException: -128
        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.readCharsOrNull(ConsoleImpl.java:486)
| State engine terminated. at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.write(ConsoleImpl.java:402)
        at java.base/java.io.OutputStream.write(OutputStream.java:167)

        at java.base/java.io.OutputStream.write(OutputStream.java:124)
| Restore definitions with: /reload -restore at jdk.jshell/jdk.jshell.execution.DemultiplexInput.run(DemultiplexInput.java:74)

$1 ==>

jshell> System.console().writer().write("a".repeat(128))
Exception in thread "output reader" java.lang.NegativeArraySizeException: -128
| State engine terminated. at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.readCharsOrNull(ConsoleImpl.java:486)

        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.write(ConsoleImpl.java:402)
        at java.base/java.io.OutputStream.write(OutputStream.java:167)
        at java.base/java.io.OutputStream.write(OutputStream.java:124)
        at jdk.jshell/jdk.jshell.execution.DemultiplexInput.run(DemultiplexInput.java:74)
| Restore definitions with: /reload -restore

jshell> IO.println("a".repeat(255))
Exception in thread "output reader" java.lang.NegativeArraySizeException: -1
        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.readCharsOrNull(ConsoleImpl.java:486)
        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.write(ConsoleImpl.java:402)
        at java.base/java.io.OutputStream.write(OutputStream.java:167)
        at java.base/java.io.OutputStream.write(OutputStream.java:124)
        at jdk.jshell/jdk.jshell.execution.DemultiplexInput.run(DemultiplexInput.java:74)
| State engine terminated.
| Restore definitions with: /reload -restore

jshell> IO.println("a".repeat(384))
Exception in thread "output reader" java.lang.NegativeArraySizeException: -128
        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.readCharsOrNull(ConsoleImpl.java:486)
        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.write(ConsoleImpl.java:402)
| State engine terminated. at java.base/java.io.OutputStream.write(OutputStream.java:167)

        at java.base/java.io.OutputStream.write(OutputStream.java:124)
        at jdk.jshell/jdk.jshell.execution.DemultiplexInput.run(DemultiplexInput.java:74)
| Restore definitions with: /reload -restore

jshell> IO.println("a".repeat(511))
Exception in thread "output reader" java.lang.NegativeArraySizeException: -1
        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.readCharsOrNull(ConsoleImpl.java:486)
        at jdk.jshell/jdk.jshell.execution.impl.ConsoleImpl$ConsoleOutputStream.write(ConsoleImpl.java:402)
        at java.base/java.io.OutputStream.write(OutputStream.java:167)
        at java.base/java.io.OutputStream.write(OutputStream.java:124)
        at jdk.jshell/jdk.jshell.execution.DemultiplexInput.run(DemultiplexInput.java:74)
| State engine terminated.
| Restore definitions with: /reload -restore

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