From 1fd6faf0b9874e0962ab790e12b1f12fabac893e Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Fri, 12 Jun 2026 17:10:45 +0100
Subject: Add Java field declaration

---
 .../hobgoblin/compiler/output/lang/java/JavaWriter.java     | 13 +++++++++++++
 .../output/lang/java/ast/JavaClassBodyDeclaration.java      |  2 +-
 .../compiler/output/lang/java/ast/JavaFieldDeclaration.java |  8 ++++++++
 .../compiler/output/lang/java/JavaWriterTests.java          | 13 +++++++++++++
 4 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaFieldDeclaration.java

diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriter.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriter.java
index c9f62b3..2ae41bb 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriter.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriter.java
@@ -130,6 +130,10 @@ public class JavaWriter implements AutoCloseable {
                 writeConstructorDeclaration(constructorDeclaration);
             }
 
+            case JavaFieldDeclaration fieldDeclaration -> {
+                writeFieldDeclaration(fieldDeclaration);
+            }
+
             case JavaMethodDeclaration methodDeclaration -> {
                 writeMethodDeclaration(methodDeclaration);
             }
@@ -232,6 +236,15 @@ public class JavaWriter implements AutoCloseable {
         this.writer.write(fieldAccess.fieldName());
     }
 
+    private void writeFieldDeclaration(JavaFieldDeclaration fieldDeclaration) throws IOException {
+        this.writeVisibility(fieldDeclaration.visibility());
+        this.writer.write(" final ");
+        this.writeTypeRef(fieldDeclaration.type());
+        this.writer.write(" ");
+        this.writer.write(fieldDeclaration.name());
+        this.writer.write(";");
+    }
+
     private void writeImplements(List<JavaTypeRef> implementsTypes) throws IOException {
         if (!implementsTypes.isEmpty()) {
             this.writer.write("implements ");
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaClassBodyDeclaration.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaClassBodyDeclaration.java
index 3bee614..5ce363d 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaClassBodyDeclaration.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaClassBodyDeclaration.java
@@ -1,4 +1,4 @@
 package org.zwobble.hobgoblin.compiler.output.lang.java.ast;
 
-public sealed interface JavaClassBodyDeclaration permits JavaConstructorDeclaration, JavaMethodDeclaration, JavaTypeDeclaration {
+public sealed interface JavaClassBodyDeclaration permits JavaConstructorDeclaration, JavaFieldDeclaration, JavaMethodDeclaration, JavaTypeDeclaration {
 }
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaFieldDeclaration.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaFieldDeclaration.java
new file mode 100644
index 0000000..14855de
--- /dev/null
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaFieldDeclaration.java
@@ -0,0 +1,8 @@
+package org.zwobble.hobgoblin.compiler.output.lang.java.ast;
+
+public record JavaFieldDeclaration(
+    JavaVisibility visibility,
+    JavaTypeRef type,
+    String name
+) implements JavaClassBodyDeclaration {
+}
diff --git a/src/test/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriterTests.java b/src/test/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriterTests.java
index 6819760..427d099 100644
--- a/src/test/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriterTests.java
+++ b/src/test/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriterTests.java
@@ -668,6 +668,19 @@ public class JavaWriterTests {
         ));
     }
 
+    @Test
+    public void fieldDeclaration() throws IOException {
+        var java = new JavaFieldDeclaration(
+            JavaVisibility.PRIVATE,
+            JavaTypeRef.INT,
+            "count"
+        );
+
+        var string = write(writer -> writer.writeClassBodyDeclaration(java));
+
+        assertThat(string, equalTo("private final int count;"));
+    }
+
     @Test
     public void block() throws IOException {
         var java = new JavaBlock(List.of(
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