bind: support exported variables

basic types, struct*, interface.

TODO: error, non-pointer struct, pointer basic types, slice of bytes.

Update golang/go#12475.

Change-Id: I5ff91059b1f963b0cadb6f76cb0e12f7b6b98718
Reviewed-on: https://go-review.googlesource.com/15340
Reviewed-by: David Crawshaw <crawshaw@golang.org>

bind/java/SeqTest.java

@@ -33,6 +33,34 @@ public class SeqTest extends AndroidTestCase {
     assertEquals("const MaxFloat32", 3.40282346638528859811704183484516925440e+38, Testpkg.MaxFloat32, 0.0001);
     assertEquals("const Log2E", 1/0.693147180559945309417232121458176568075500134360255254120680009, Testpkg.Log2E, 0.0001);
   }
+
+  public void testVar() {
+    assertEquals("var StringVar", "a string var", Testpkg.getStringVar());
+
+    String newStringVar = "a new string var";
+    Testpkg.setStringVar(newStringVar);
+    assertEquals("var StringVar", newStringVar, Testpkg.getStringVar());
+
+    assertEquals("var IntVar", 77, Testpkg.getIntVar());
+
+    long newIntVar = 777;
+    Testpkg.setIntVar(newIntVar);
+    assertEquals("var IntVar", newIntVar, Testpkg.getIntVar());
+
+    Testpkg.S s0 = Testpkg.getStructVar();
+    assertEquals("var StructVar", "a struct var", s0.String());
+    Testpkg.S s1 = Testpkg.New();
+    Testpkg.setStructVar(s1);
+    assertEquals("var StructVar", s1.String(), Testpkg.getStructVar().String());
+
+    // TODO(hyangah): handle nil return value (translate to null)
+
+    AnI obj = new AnI();
+    obj.name = "this is an I";
+    Testpkg.setInterfaceVar(obj);
+    assertEquals("var InterfaceVar", obj.String(), Testpkg.getInterfaceVar().String());
+  }
+
   public void testAssets() {
     String want = "Hello, Assets.\n";
     String got = Testpkg.ReadAsset();

bind/java/testpkg/testpkg.go

@@ -39,6 +39,13 @@ const (
 	Log2E                          = math.Log2E
 )
 
+var (
+	StringVar    = "a string var"
+	IntVar       = 77
+	StructVar    = &S{name: "a struct var"}
+	InterfaceVar I
+)
+
 type I interface {
 	F()
 
@@ -104,8 +111,10 @@ func finalizeInner(a *int) {
 	numSCollected++
 }
 
+var seq = 0
+
 func New() *S {
-	s := &S{innerObj: new(int), name: "new"}
+	s := &S{innerObj: new(int), name: fmt.Sprintf("new%d", seq)}
 	runtime.SetFinalizer(s.innerObj, finalizeInner)
 	return s
 }