Add CLDC 1.1 core API compatibility

[dlunch]

Summary

• add the missing CLDC 1.1 exception and error hierarchy and correct standard class names
• complete the core java.io stream, reader/writer, data stream, charset, and PrintStream contracts
• add CLDC-compatible Class, Thread, Throwable, Random, Vector, Hashtable, date, calendar, and time zone APIs

Compatibility

• preserve split multibyte input and UTF-16 surrogate pairs across stream calls
• use Java-compatible primitive formatting, modified UTF handling, collection behavior, and the standard 48-bit Random algorithm
• keep thread interruption state-based and time zone support focused on GMT/UTC and fixed offsets within the current runtime constraints

Validation

• cargo test --workspace (178 passed, 1 ignored)
• cargo clippy --workspace --all-targets
• cargo fmt --all -- --check
• git diff --check

[codecov]

Codecov Report

❌ Patch coverage is 79.59184% with 350 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.37%. Comparing base (7f6b1a9) to head (08d84ae).

Files with missing lines	Patch %	Lines
java_runtime/src/classes/java/io/reader.rs	29.23%	46 Missing ⚠️
java_runtime/src/classes/java/io/input_stream.rs	8.51%	43 Missing ⚠️
java_runtime/src/classes/java/io/print_stream.rs	79.24%	33 Missing ⚠️
..._runtime/src/classes/java/util/simple_time_zone.rs	52.94%	24 Missing ⚠️
...runtime/src/classes/java/io/input_stream_reader.rs	77.77%	18 Missing ⚠️
java_runtime/src/classes/java/io/writer.rs	60.00%	18 Missing ⚠️
java_runtime/src/classes/java/lang/thread.rs	87.14%	18 Missing ⚠️
...me/src/classes/java/io/byte_array_output_stream.rs	58.53%	17 Missing ⚠️
java_runtime/src/classes/java/util/vector.rs	88.54%	15 Missing ⚠️
...runtime/src/classes/java/io/filter_input_stream.rs	44.44%	10 Missing ⚠️
... and 23 more

Additional details and impacted files

@@ Coverage Diff @@## main #177 +/- ##
==========================================
- Coverage 85.51% 85.37% -0.14% 
==========================================
Files 181 191 +10 Lines 15588 17054 +1466 ==========================================
+ Hits 13330 14560 +1230 - Misses 2258 2494 +236 

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[chatgpt-codex-connector]

💡 Codex Review

RustJava/java_runtime/src/classes/java/lang/class.rs

Line 176 in 08d84ae

Ok(jvm.is_inherited_from(&*other_rust_class,&rust_class.name()))

Use JVM assignability for array classes

When both Class objects are arrays, this falls back to inheritance only. Array class definitions report Object as the superclass and no interfaces, so cases such as Object[].class.isAssignableFrom(String[].class) or Cloneable.class.isAssignableFrom(String[].class) return false even though the JVM's normal type checks already support array covariance and array supertypes. Reflection-based type checks over arrays will therefore reject valid assignments; this should use the same type-assignability path as isInstance rather than is_inherited_from.

---

RustJava/java_runtime/src/classes/java/io/input_stream_reader.rs

Line 240 in 08d84ae

Ok(to_copy)

Avoid returning zero from non-empty reads

When the decoder withholds an incomplete multibyte sequence and no characters are buffered yet, for example a UTF-8 stream whose read returns only the first byte of a 3-byte character, writeBufSize stays 0 and this returns 0 even though length > 0. Reader.read(char[], off, len) is only allowed to return 0 for zero-length requests, so callers that loop until EOF or positive progress can spin on split/truncated multibyte input. Keep reading until a character, EOF/replacement, or an exception is available before returning.

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[Copilot]

Pull request overview

This PR extends the RustJava runtime toward CLDC 1.1 core API compatibility, adding missing class hierarchies and filling in key java.io, java.lang, and java.util behaviors so CLDC-era code can run with closer-to-spec semantics.

Changes:

• Adds/extends CLDC 1.1 core library surface area (exceptions/errors, Class, Thread, Throwable, Random, Vector, Hashtable, date/calendar/time zone).
• Completes important java.io stream/reader/writer/data stream behavior (including modified UTF and charset handling).
• Expands test coverage for the added CLDC contracts across java.lang, java.util, and java.io.

Reviewed changes

Copilot reviewed 61 out of 61 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
jvm/src/jvm.rs	Bootstrap loads Runnable; thread count API
java_runtime/src/loader.rs	Registers newly added runtime classes
java_runtime/src/classes/java/util/vector.rs	Adds CLDC Vector legacy APIs
java_runtime/src/classes/java/util/time_zone.rs	Adds TimeZone ID/default/available IDs
java_runtime/src/classes/java/util/simple_time_zone.rs	Implements raw offset and validations
java_runtime/src/classes/java/util/random.rs	Implements CLDC Random algorithms/APIs
java_runtime/src/classes/java/util/hashtable.rs	Adds legacy Hashtable APIs + toString/rehash
java_runtime/src/classes/java/util/gregorian_calendar.rs	Time/timezone handling and field validation
java_runtime/src/classes/java/util/empty_stack_exception.rs	Corrects EmptyStackException name/package
java_runtime/src/classes/java/util/date.rs	Implements Date equals/hashCode/toString
java_runtime/src/classes/java/util/calendar.rs	Adds millis/timezone and comparison APIs
java_runtime/src/classes/java/net/url_connection.rs	Fixes UnknownServiceException package
java_runtime/src/classes/java/net/unknown_service_exception.rs	Corrects UnknownServiceException name/package
java_runtime/src/classes/java/lang/virtual_machine_error.rs	Adds VirtualMachineError base type
java_runtime/src/classes/java/lang/out_of_memory_error.rs	Adds OutOfMemoryError under VME
java_runtime/src/classes/java/lang/instantiation_exception.rs	Adds InstantiationException class
java_runtime/src/classes/java/lang/illegal_thread_state_exception.rs	Adds IllegalThreadStateException class
java_runtime/src/classes/java/lang/illegal_monitor_state_exception.rs	Adds IllegalMonitorStateException class
java_runtime/src/classes/java/lang/illegal_access_exception.rs	Adds IllegalAccessException class
java_runtime/src/classes/java/lang/throwable.rs	Adds Throwable.getMessage
java_runtime/src/classes/java/lang/thread.rs	Adds CLDC Thread metadata/state APIs
java_runtime/src/classes/java/lang/class.rs	Adds CLDC Class query/newInstance/toString
java_runtime/src/classes/java/lang.rs	Exports and wires new lang classes
java_runtime/src/classes/java/io/writer.rs	Aligns Writer API to CLDC/JDK contracts
java_runtime/src/classes/java/io/reader.rs	Aligns Reader API + skip/mark defaults
java_runtime/src/classes/java/io/print_writer.rs	Updates PrintWriter write/flush/close signatures
java_runtime/src/classes/java/io/print_stream.rs	Implements broader PrintStream contract
java_runtime/src/classes/java/io/output_stream_writer.rs	Adds OutputStreamWriter with charset handling
java_runtime/src/classes/java/io/interrupted_io_exception.rs	Adds InterruptedIOException + field
java_runtime/src/classes/java/io/input_stream.rs	Implements InputStream read/available/close defaults
java_runtime/src/classes/java/io/input_stream_reader.rs	Charset ctor + split multibyte handling
java_runtime/src/classes/java/io/filter_output_stream.rs	Adds flush/close forwarding
java_runtime/src/classes/java/io/filter_input_stream.rs	Adds skip/mark/markSupported forwarding
java_runtime/src/classes/java/io/data_output.rs	Expands DataOutput interface surface
java_runtime/src/classes/java/io/data_output_stream.rs	Implements CLDC primitive + modified UTF writes
java_runtime/src/classes/java/io/data_input.rs	Adds readUnsignedByte requirement
java_runtime/src/classes/java/io/data_input_stream.rs	Implements required reads + modified UTF decoding
java_runtime/src/classes/java/io/byte_array_output_stream.rs	Adds write([BII), toString, size validation
java_runtime/src/classes/java/io/byte_array_input_stream.rs	Adds bounds checks + markSupported
java_runtime/src/classes/java/io/string_writer.rs	Updates write signature; adds flush/close
java_runtime/src/classes/java/io/unsupported_encoding_exception.rs	Adds UnsupportedEncodingException
java_runtime/src/classes/java/io/utf_data_format_exception.rs	Adds UTFDataFormatException
java_runtime/src/classes/java/io.rs	Wires new java.io classes
java_runtime/tests/classes/java/util/test_vector.rs	Adds Vector CLDC legacy API test
java_runtime/tests/classes/java/util/test_timezone.rs	Expands TimeZone behavior tests
java_runtime/tests/classes/java/util/test_random.rs	Adds CLDC Random algorithm tests
java_runtime/tests/classes/java/util/test_hashtable.rs	Adds Hashtable legacy API tests
java_runtime/tests/classes/java/util/test_gregorian_calendar.rs	Adds Calendar time/comparison API tests
java_runtime/tests/classes/java/util/test_date.rs	Adds Date CLDC value contract test
java_runtime/tests/classes/java/util/mod.rs	Registers new util tests
java_runtime/tests/classes/java/lang/test_throwable.rs	Adds getMessage coverage
java_runtime/tests/classes/java/lang/test_thread.rs	Adds CLDC Thread metadata/state test
java_runtime/tests/classes/java/lang/test_cldc11_exceptions.rs	Adds CLDC exception hierarchy tests
java_runtime/tests/classes/java/lang/test_class.rs	Adds CLDC Class query/newInstance tests
java_runtime/tests/classes/java/lang/mod.rs	Registers new lang tests
java_runtime/tests/classes/java/io/test_string_writer.rs	Updates Writer signature expectations
java_runtime/tests/classes/java/io/test_print_stream.rs	Adds PrintStream CLDC API tests
java_runtime/tests/classes/java/io/test_output_stream_writer.rs	Adds OutputStreamWriter encoding/surrogate tests
java_runtime/tests/classes/java/io/test_input_stream_reader.rs	Adds ISR split multibyte/encoding tests
java_runtime/tests/classes/java/io/test_data_output_stream.rs	Adds CLDC data stream round-trip tests
java_runtime/tests/classes/java/io/mod.rs	Registers new io tests

---

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[dlunch]

Addressed the remaining actionable review findings in ad52cbc:

• Class.isAssignableFrom now uses the JVM type-assignability path, including array covariance and Object/Cloneable/Serializable array supertypes.
• InputStreamReader now keeps reading split multibyte input until it can return a character or EOF instead of returning 0 for a non-empty request.
• Added regression tests for both behaviors.

Verified with cargo test --workspace and stable/beta Clippy with warnings denied. The four Vector/modified UTF-8 threads were answered and resolved as JDK-compatible behavior.