diff --git a/JavaExamples.java b/JavaExamples.java
index 3babfd7..3a18640 100644
--- a/JavaExamples.java
+++ b/JavaExamples.java
@@ -1,84 +1,86 @@
 /// Java Examples
 import java.util.*;
+import qual.Immutable;
 import qual.Mutable;
 
-// Mutating immut set, `s` is immut
-void foo(Set<String> s) {
-  Set<String> new_s = s;
-  @Mutable Set<String> new_s1 = s; // ERROR
-  new_s.add("x"); // ERROR
-}
+public class JavaExamples {
+    // Mutating immut set, `s` is immut
+    void foo(@Immutable Set<String> s) {
+        Set<String> new_s = s; // Flow sensitive will refine this to @Immutable
+        @Mutable Set<String> new_s1 = s; // ERROR, type incompatible
+        new_s.add("x"); // ERROR
+    }
 
-// Mutating immut set, `new_s` is immut
-void foo1(@Mutable Set<String> s) {
-  Set<String> new_s = new HashSet<>(s);
-  Set<String> new_s1 = s;
-  new_s.add("x"); // ERROR
-  new_s1.add("x"); //OK
-}
+    // Mutating immut set, `new_s` is immut
+    void foo1(@Mutable Set<String> s) {
+        @Immutable Set<String> new_s = new @Immutable HashSet<>(s);
+        Set<String> new_s1 = s; // Flow sensitive will refine this to @Mutable
+        new_s.add("x"); // ERROR
+        new_s1.add("x"); //OK
+    }
 
-// Mutating mut set
-void foo2(Set<String> s) {
-  @Mutable Set<String> new_s = new HashSet<>(s);
-  new_s.add("x"); // OK
-}
+    // Mutating mut set
+    void foo2(Set<String> s) {
+        @Mutable Set<String> new_s = new HashSet<>(s);
+        new_s.add("x"); // OK
+    }
+
+    // Type parameter mutability
+    void foo3(Set<List<String>> s, List<String> l) {
+        assert s.get(l) != null;
+        List<String> v = s.get(l);
+        @Mutable List<String> v2 = s.get(l); // ERROR
+        v.add("x"); // ERROR
+    }
+
+    void foo4(Person p) {
+        p.name = "Jenny"; // ERROR, this should be forbid by compiler by adding final before String
+        p.family.add("Jenny"); // ERROR, can not mutate immut list
+    }
 
-// Type parameter mutability
-void foo3(Set<List<String>> s, List<String> l) {
-  assert s.get(l) != null;
-  List<String> v = s.get(l);
-  @Mutable List<String> v2 = s.get(l); // ERROR
-  v.add("x"); // ERROR
+    void foo5(MutPerson p) {
+        p.name = "Jenny"; // OK
+        p.family.add("Jenny"); // OK
+        p.getFamily().add("Jenny"); // OK
+    }
 }
 
 // Class and its immut members
 class Person {
-  String name;
-  List<String> family;
+    String name; // String is default @Immutable, use final to prevent reassignment
+    @Immutable List<String> family;
 
-  Person(String n, List<String> f) {
-    this.name = n; // OK
-    this.family = f; // OK
-    this.family.add("Mom"); // ERROR
-  }
+    Person(String n, @Immutable List<String> f) {
+        this.name = n; // OK
+        this.family = f; // OK
+        this.family.add("Mom"); // ERROR
+    }
 
-  void setName(String n) {
-    this.name = n; // ERROR
-  }
+    void setName(String n) {
+        this.name = n; // ERROR, this should be forbid by compiler by adding final before String
+    }
 
-  @Mutable List<String> getFamily() {
-    return family; // ERROR
-  }
-}
-
-void foo4(Person p) {
-  p.name = "Jenny"; // ERROR
-  p.family.add("Jenny"); // ERROR
-  p.family.getFamily().add("Jenny"); // OK
+    @Mutable List<String> getFamily() {
+        return family; // ERROR, type incompatible
+    }
 }
 
 // Class and its mut members
 class MutPerson {
-  @Mutable String name;
-  @Mutable List<String> family;
+    String name; // String is default @Immutable in PICO
+    @Mutable List<String> family;
 
-  Person(String n, List<String> f) {
-    this.name = n; // OK
-    this.family = f; // OK
-    this.family.add("Mom"); // OK
-  }
+    MutPerson(String n, List<String> f) {
+        this.name = n; // OK
+        this.family = f; // OK
+        this.family.add("Mom"); // OK
+    }
 
-  void setName(String n) {
-    this.name = n; // OK
-  }
-
-  List<String> getFamily() {
-    return family; // OK
-  }
-}
+    void setName(String n) {
+        this.name = n; // OK
+    }
 
-void foo5(MutPerson p) {
-  p.name = "Jenny"; // OK
-  p.family.add("Jenny"); // OK
-  p.family.getFamily().add("Jenny"); // ERROR
+    List<String> getFamily() {
+        return family; // OK
+    }
 }