Add java/lang/StringBuffer::length()I

Author: dlunch

java_runtime/src/classes/java/lang/string_buffer.rs

@@ -43,6 +43,7 @@ impl StringBuffer {
                 JavaMethodProto::new("append", "([CII)Ljava/lang/StringBuffer;", Self::append_char_array, Default::default()),
                 JavaMethodProto::new("toString", "()Ljava/lang/String;", Self::to_string, Default::default()),
                 JavaMethodProto::new("setLength", "(I)V", Self::set_length, Default::default()),
+                JavaMethodProto::new("length", "()I", Self::length, Default::default()),
             ],
             fields: vec![
                 JavaFieldProto::new("value", "[C", Default::default()),
@@ -221,4 +222,12 @@ impl StringBuffer {
 
         Ok(())
     }
+
+   async fn length(jvm: &Jvm, _: &mut RuntimeContext, this: ClassInstanceRef<Self>) -> Result<i32> {
+        tracing::debug!("java.lang.StringBuffer::length({:?})", &this);
+
+        let count: i32 = jvm.get_field(&this, "count", "I").await?;
+
+        Ok(count)
+    }
 }

java_runtime/tests/classes/java/lang/test_string_buffer.rs

@@ -21,6 +21,9 @@ async fn test_string_buffer() -> Result<()> {
         .invoke_virtual(&string_buffer, "append", "(J)Ljava/lang/StringBuffer;", (42i64,))
         .await?;
 
+    let length: i32 = jvm.invoke_virtual(&string_buffer, "length", "()I", ()).await?;
+    assert_eq!(length, 12);
+
     let result = jvm.invoke_virtual(&string_buffer, "toString", "()Ljava/lang/String;", ()).await?;
     let result = JavaLangString::to_rust_string(&jvm, &result).await?;