Added bitfield code samples (#3894)

Co-authored-by: M Sazzadul Hoque <[email protected]>

src/test/java/io/redis/examples/BitfieldExample.java

@@ -0,0 +1,52 @@
+// EXAMPLE: bitfield_tutorial
+// REMOVE_START
+package io.redis.examples;
+
+import org.junit.Assert;
+import org.junit.Test;
+import java.util.List;
+// REMOVE_END
+
+// HIDE_START
+import redis.clients.jedis.UnifiedJedis;
+// HIDE_END
+
+// HIDE_START
+public class BitfieldExample {
+    @Test
+    public void run() {
+        UnifiedJedis jedis = new UnifiedJedis("redis://localhost:6379");
+// HIDE_END
+
+        //REMOVE_START
+        // Clear any keys here before using them in tests.
+        jedis.del("bike:1:stats");
+        //REMOVE_END
+
+        // STEP_START bf
+        List<Long> res1 = jedis.bitfield("bike:1:stats", "SET", "u32", "#0", "1000");
+        System.out.println(res1);   // >>> [0]
+
+        List<Long> res2 = jedis.bitfield("bike:1:stats", "INCRBY", "u32", "#0", "-50", "INCRBY", "u32", "#1", "1");
+        System.out.println(res2);   // >>> [950, 1]
+
+        List<Long> res3 = jedis.bitfield("bike:1:stats", "INCRBY", "u32", "#0", "500", "INCRBY", "u32", "#1", "1");
+        System.out.println(res3);   // >>> [1450, 2]
+
+        List<Long> res4 = jedis.bitfield("bike:1:stats", "GET", "u32", "#0", "GET", "u32", "#1");
+        System.out.println(res4);   // >>> [1450, 2]
+        // STEP_END
+
+        // Tests for 'bf' step.
+        // REMOVE_START
+        Assert.assertEquals("[0]", res1.toString());
+        Assert.assertEquals("[950, 1]", res2.toString());
+        Assert.assertEquals("[1450, 2]", res3.toString());
+        Assert.assertEquals("[1450, 2]", res4.toString());
+        // REMOVE_END
+
+// HIDE_START
+        jedis.close();
+    }
+}
+// HIDE_END