Add trivial class static initialization

tests/integration_test.rs

@@ -81,3 +81,30 @@ fn should_do_arrays() {
     let last_frame_value = vm.run("Array").unwrap();
     assert_eq!(740, last_frame_value.unwrap())
 }
+
+#[test]
+fn should_do_class_static_initialization() {
+    let vm = VM::new(
+        vec!["tests/test_data/StaticInitialization.class"],
+        "tests/test_data/std",
+    )
+    .unwrap();
+    let last_frame_value = vm.run("StaticInitialization").unwrap();
+    assert_eq!(257, last_frame_value.unwrap())
+}
+
+#[ignore]
+#[test]
+fn should_do_class_static_initialization_multiple_classes() {
+    let vm = VM::new(
+        vec![
+            "tests/test_data/Dependable.class",
+            "tests/test_data/DependsOnDependable.class",
+            "tests/test_data/StaticInitializationUser.class",
+        ],
+        "tests/test_data/std",
+    )
+    .unwrap();
+    let last_frame_value = vm.run("StaticInitializationUser").unwrap();
+    assert_eq!(350, last_frame_value.unwrap())
+}

tests/test_data/Dependable.java

@@ -0,0 +1,8 @@
+
+public class Dependable {
+    static int valueA = 100;
+
+    static {
+        valueA = 200;
+    }
+}

tests/test_data/DependsOnDependable.java

@@ -0,0 +1,8 @@
+
+public class DependsOnDependable {
+    static int valueB = Dependable.valueA + 50;
+
+    static {
+        valueB += 100;
+    }
+}

tests/test_data/StaticInitialization.java

@@ -0,0 +1,35 @@
+
+public class StaticInitialization {
+    private static final int STATIC_FINAL_FIELD = init();
+    private static int staticField1;
+    private static int staticField2;
+    private static int[] staticArray;
+
+    // Static initializer block
+    static {
+        staticField1 = 5; // Direct static field initialization
+        staticArray = new int[staticField1]; // Initialize array in static block
+        for (int i = 0; i < staticArray.length; i++) {
+            staticArray[i] = i * staticField1;
+        }
+    }
+
+    private static int init() {
+        return 42;
+    }
+
+    public static void main(String[] args) {
+        int arraySum = 0;
+        for (int i = 0; i < staticArray.length; i++) {
+            arraySum += staticArray[i];
+        }
+
+        int result = STATIC_FINAL_FIELD + staticField1 + staticField2 + arraySum;
+    }
+
+    // Another static block (executed in order of appearance)
+    static {
+        staticField1 += 50; // Modify staticField1
+        staticField2 = staticField1 * 2; // Initialize staticField2 based on staticField1
+    }
+}

tests/test_data/StaticInitializationUser.java

@@ -0,0 +1,6 @@
+
+public class StaticInitializationUser {
+    public static void main(String[] args) {
+        int result = DependsOnDependable.valueB;
+    }
+}

vm/src/vm.rs

@@ -19,6 +19,14 @@ impl VM {
             .get_method_by_name_signature(main_class_name, "main:([Ljava/lang/String;)V")?;
 
         let mut engine = Engine::new(&self.class_loader.method_area());
+
+        for (class_name, java_class) in self.class_loader.method_area().loaded_classes.iter() {
+            if let Some(java_method) = java_class.methods.method_by_signature.get("<clinit>:()V") {
+                println!("About to initialize java class {class_name} java_method={java_method:?}");
+                engine.execute(java_method)?; //todo implement multiclass correct initialization order
+            }
+        }
+
         engine.execute(main_method)
     }
 }