fix: correct Java 8 string handling to encode Rust strings as UTF-16

ristretto_vm/src/java_object.rs

@@ -1,8 +1,7 @@
 use crate::Error::InternalError;
 use crate::{Result, VM};
 use ristretto_classfile::{mutf8, Version};
-use ristretto_classloader::Error::ParseError;
-use ristretto_classloader::{Class, Object, Reference, Value};
+use ristretto_classloader::{Class, ConcurrentVec, Object, Reference, Value};
 use std::sync::Arc;
 
 const JAVA_8: Version = Version::Java8 { minor: 0 };
@@ -190,13 +189,10 @@
         // In Java 9 and later, the value field is a byte array.
         let java_class_file_version = vm.java_class_file_version();
         let array = if java_class_file_version <= &JAVA_8 {
-            let bytes = mutf8::to_bytes(self)?;
-            let utf8_string =
-                String::from_utf8(bytes).map_err(|error| ParseError(error.to_string()))?;
-            let chars: Vec<char> = utf8_string.chars().collect();
-            Reference::from(chars)
+            let chars = self.encode_utf16().collect::<Vec<u16>>();
+            Reference::CharArray(ConcurrentVec::from(chars))
         } else {
             if java_class_file_version >= &JAVA_17 {
                 object.set_value("hashIsZero", Value::Int(0))?;
             }
             object.set_value("coder", Value::Int(0))?; // LATIN1

ristretto_vm/src/local_variables.rs

@@ -189,8 +189,10 @@ impl Display for LocalVariables {
                 continue;
             };
             let value = local.to_string();
-            if value.len() > 100 {
-                locals.push(format!("{}...", &value[..97]));
+            let chars: Vec<char> = value.chars().collect();
+            if chars.len() > 100 {
+                let value = chars.iter().take(97).collect::<String>();
+                locals.push(format!("{value}..."));
             } else {
                 locals.push(value);
             }

ristretto_vm/src/operand_stack.rs

@@ -152,8 +152,10 @@
                 let mut values = Vec::new();
                 for stack_entry in &stack {
                     let value = stack_entry.to_string();
-                    if value.len() > 100 {
-                        values.push(format!("{}...", &value[..97]));
+                    let chars: Vec<char> = value.chars().collect();
+                    if chars.len() > 100 {
+                        let value = chars.iter().take(97).collect::<String>();
+                        values.push(format!("{value}..."));
                     } else {
                         values.push(value);
                     }