bind/java: custom int-keyed hashmap

This removes the last dependency on an Android class in the running
gobind code. (Tests still need some work before they will run on the
desktop.)

Change-Id: I49bfb545d4587c6f430c0938fa1ca4d513b56d77
Reviewed-on: https://go-review.googlesource.com/17252
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>

bind/java/SeqTest.java

@@ -316,6 +316,42 @@ public class SeqTest extends AndroidTestCase {
     assertFalse("want obj to be kept live by Go", finalizedAnI);
   }
 
+  private int countI = 0;
+
+  private class CountI extends Testpkg.I.Stub {
+    public void F() { countI++; }
+
+    public void E() throws Exception {}
+    public Testpkg.I I() { return null; }
+    public Testpkg.S S() { return null; }
+    public String StoString(Testpkg.S s) { return ""; }
+    public long V() { return 0; }
+    public long VE() throws Exception { return 0; }
+    public String String() { return ""; }
+  }
+
+  public void testGoRefMapGrow() {
+    CountI obj = new CountI();
+    Testpkg.Keep(obj);
+
+    // Push active references beyond base map size.
+    for (int i = 0; i < 24; i++) {
+      CountI o = new CountI();
+      Testpkg.CallF(o);
+      if (i%3==0) {
+        Testpkg.Keep(o);
+      }
+    }
+    runGC();
+    for (int i = 0; i < 128; i++) {
+      Testpkg.CallF(new CountI());
+    }
+
+    Testpkg.CallF(obj); // original object needs to work.
+
+    assertEquals(countI, 1+24+128);
+  }
+
   private void runGC() {
     System.gc();
     System.runFinalization();