Update Java samples to match C samples.

Also add all of the samples as Java tests, referencing the output of the C
samples.

bindings/java/samples/Utils.java

@@ -0,0 +1,49 @@
+package samples;
+
+public class Utils {
+    public static byte[] hexToBytes(String s) {
+        int len = s.length();
+        byte[] data = new byte[len / 2];
+        for (int i = 0; i < len; i += 2) {
+            data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4) +
+                Character.digit(s.charAt(i + 1), 16));
+        }
+        return data;
+    }
+
+    public static final int toInt(byte val[]) {
+        int res = 0;
+        for (int i = 0; i < val.length; i++) {
+            int v = val[i] & 0xff;
+            res = res + (v << (i * 8));
+        }
+        return res;
+    }
+
+    public static final long toLong(byte val[]) {
+        long res = 0;
+        for (int i = 0; i < val.length; i++) {
+            long v = val[i] & 0xff;
+            res = res + (v << (i * 8));
+        }
+        return res;
+    }
+
+    public static final byte[] toBytes(int val) {
+        byte[] res = new byte[4];
+        for (int i = 0; i < 4; i++) {
+            res[i] = (byte) (val & 0xff);
+            val >>>= 8;
+        }
+        return res;
+    }
+
+    public static final byte[] toBytes(long val) {
+        byte[] res = new byte[8];
+        for (int i = 0; i < 8; i++) {
+            res[i] = (byte) (val & 0xff);
+            val >>>= 8;
+        }
+        return res;
+    }
+}