Java: Add lindex command. (List Command Group) (valkey-io#1219)

* Java: Add lindex command. (List Command Group) (valkey-io#158)

* Minor documentation update + changed param from int to long + minor IT update.

java/client/src/main/java/glide/api/BaseClient.java

@@ -36,6 +36,7 @@
 import static redis_request.RedisRequestOuterClass.RequestType.LRange;
 import static redis_request.RedisRequestOuterClass.RequestType.LRem;
 import static redis_request.RedisRequestOuterClass.RequestType.LTrim;
+import static redis_request.RedisRequestOuterClass.RequestType.Lindex;
 import static redis_request.RedisRequestOuterClass.RequestType.MGet;
 import static redis_request.RedisRequestOuterClass.RequestType.MSet;
 import static redis_request.RedisRequestOuterClass.RequestType.PExpire;
@@ -445,6 +446,12 @@ public CompletableFuture<String[]> lrange(@NonNull String key, long start, long
  response -> castArray(handleArrayOrNullResponse(response), String.class));
  }
 
+ @Override
+ public CompletableFuture<String> lindex(@NonNull String key, long index) {
+ return commandManager.submitNewCommand(
+ Lindex, new String[] {key, Long.toString(index)}, this::handleStringOrNullResponse);
+ }
+
  @Override
  public CompletableFuture<String> ltrim(@NonNull String key, long start, long end) {
  return commandManager.submitNewCommand(

java/client/src/main/java/glide/api/commands/ListBaseCommands.java

@@ -103,6 +103,30 @@ public interface ListBaseCommands {
  */
  CompletableFuture<String[]> lrange(String key, long start, long end);
 
+ /**
+ * Returns the element at <code>index</code> from the list stored at <code>key</code>.<br>
+ * The index is zero-based, so <code>0</code> means the first element, <code>1</code> the second
+ * element and so on. Negative indices can be used to designate elements starting at the tail of
+ * the list. Here, <code>-1</code> means the last element, <code>-2</code> means the penultimate
+ * and so forth.
+ *
+ * @see <a href="https://redis.io/commands/lindex/">redis.io</a> for details.
+ * @param key The key of the list.
+ * @param index The index of the element in the list to retrieve.
+ * @return The element at <code>index</code> in the list stored at <code>key</code>.<br>
+ * If <code>index</code> is out of range or if <code>key</code> does not exist, <code>null
+ * </code> is returned.
+ * @example
+ * <pre>{@code
+ * String payload1 = client.lindex("myList", 0).get();
+ * assert payload1.equals('value1'); // Returns the first element in the list stored at 'myList'.
+ *
+ * String payload2 = client.lindex("myList", -1).get();
+ * assert payload2.equals('value3'); // Returns the last element in the list stored at 'myList'.
+ * }</pre>
+ */
+ CompletableFuture<String> lindex(String key, long index);
+
  /**
  * Trims an existing list so that it will contain only the specified range of elements specified.
  * <br>

java/client/src/main/java/glide/api/models/BaseTransaction.java

@@ -45,6 +45,7 @@
 import static redis_request.RedisRequestOuterClass.RequestType.LRange;
 import static redis_request.RedisRequestOuterClass.RequestType.LRem;
 import static redis_request.RedisRequestOuterClass.RequestType.LTrim;
+import static redis_request.RedisRequestOuterClass.RequestType.Lindex;
 import static redis_request.RedisRequestOuterClass.RequestType.MGet;
 import static redis_request.RedisRequestOuterClass.RequestType.MSet;
 import static redis_request.RedisRequestOuterClass.RequestType.PExpire;
@@ -677,6 +678,28 @@ public T lrange(@NonNull String key, long start, long end) {
  return getThis();
  }
 
+ /**
+ * Returns the element at <code>index</code> from the list stored at <code>key</code>.<br>
+ * The index is zero-based, so <code>0</code> means the first element, <code>1</code> the second
+ * element and so on. Negative indices can be used to designate elements starting at the tail of
+ * the list. Here, <code>-1</code> means the last element, <code>-2</code> means the penultimate
+ * and so forth.
+ *
+ * @see <a href="https://redis.io/commands/lindex/">redis.io</a> for details.
+ * @param key The key of the list.
+ * @param index The index of the element in the list to retrieve.
+ * @return Command Response - The element at <code>index</code> in the list stored at <code>key
+ * </code>.<br>
+ * If <code>index</code> is out of range or if <code>key</code> does not exist, <code>null
+ * </code> is returned.
+ */
+ public T lindex(@NonNull String key, long index) {
+ ArgsArray commandArgs = buildArgs(key, Long.toString(index));
+
+ protobufTransaction.addCommands(buildCommand(Lindex, commandArgs));
+ return getThis();
+ }
+
  /**
  * Trims an existing list so that it will contain only the specified range of elements specified.<br>
  * The offsets <code>start</code> and <code>end</code> are zero-based indexes, with <code>0</code> being the

java/client/src/test/java/glide/api/RedisClientTest.java

@@ -64,6 +64,7 @@
 import static redis_request.RedisRequestOuterClass.RequestType.LRange;
 import static redis_request.RedisRequestOuterClass.RequestType.LRem;
 import static redis_request.RedisRequestOuterClass.RequestType.LTrim;
+import static redis_request.RedisRequestOuterClass.RequestType.Lindex;
 import static redis_request.RedisRequestOuterClass.RequestType.MGet;
 import static redis_request.RedisRequestOuterClass.RequestType.MSet;
 import static redis_request.RedisRequestOuterClass.RequestType.PExpire;
@@ -1348,6 +1349,31 @@ public void lrange_returns_success() {
  assertEquals(value, payload);
  }
 
+ @SneakyThrows
+ @Test
+ public void lindex_returns_success() {
+ // setup
+ String key = "testKey";
+ long index = 2;
+ String[] args = new String[] {key, Long.toString(index)};
+ String value = "value";
+
+ CompletableFuture<String> testResponse = new CompletableFuture<>();
+ testResponse.complete(value);
+
+ // match on protobuf request
+ when(commandManager.<String>submitNewCommand(eq(Lindex), eq(args), any()))
+ .thenReturn(testResponse);
+
+ // exercise
+ CompletableFuture<String> response = service.lindex(key, index);
+ String payload = response.get();
+
+ // verify
+ assertEquals(testResponse, response);
+ assertEquals(value, payload);
+ }
+
  @SneakyThrows
  @Test
  public void ltrim_returns_success() {

java/client/src/test/java/glide/api/models/TransactionTests.java

@@ -43,6 +43,7 @@
 import static redis_request.RedisRequestOuterClass.RequestType.LRange;
 import static redis_request.RedisRequestOuterClass.RequestType.LRem;
 import static redis_request.RedisRequestOuterClass.RequestType.LTrim;
+import static redis_request.RedisRequestOuterClass.RequestType.Lindex;
 import static redis_request.RedisRequestOuterClass.RequestType.MGet;
 import static redis_request.RedisRequestOuterClass.RequestType.MSet;
 import static redis_request.RedisRequestOuterClass.RequestType.PExpire;
@@ -232,6 +233,9 @@ public void transaction_builds_protobuf_request(BaseTransaction<?> transaction)
  results.add(
  Pair.of(LRange, ArgsArray.newBuilder().addArgs("key").addArgs("1").addArgs("2").build()));
 
+ transaction.lindex("key", 1);
+ results.add(Pair.of(Lindex, ArgsArray.newBuilder().addArgs("key").addArgs("1").build()));
+
  transaction.ltrim("key", 1, 2);
  results.add(
  Pair.of(LTrim, ArgsArray.newBuilder().addArgs("key").addArgs("1").addArgs("2").build()));

java/integTest/src/test/java/glide/SharedCommandTests.java

@@ -684,6 +684,27 @@ public void lpush_lpop_lrange_type_error(BaseClient client) {
  assertTrue(lrangeException.getCause() instanceof RequestException);
  }
 
+ @SneakyThrows
+ @ParameterizedTest
+ @MethodSource("getClients")
+ public void lindex(BaseClient client) {
+ String key1 = UUID.randomUUID().toString();
+ String key2 = UUID.randomUUID().toString();
+ String[] valueArray = new String[] {"value1", "value2"};
+
+ assertEquals(2, client.lpush(key1, valueArray).get());
+ assertEquals(valueArray[1], client.lindex(key1, 0).get());
+ assertEquals(valueArray[0], client.lindex(key1, -1).get());
+ assertNull(client.lindex(key1, 3).get());
+ assertNull(client.lindex(key2, 3).get());
+
+ // Key exists, but it is not a List
+ assertEquals(OK, client.set(key2, "value").get());
+ Exception executionException =
+ assertThrows(ExecutionException.class, () -> client.lindex(key2, 0).get());
+ assertTrue(executionException.getCause() instanceof RequestException);
+ }
+
  @SneakyThrows
  @ParameterizedTest
  @MethodSource("getClients")

java/integTest/src/test/java/glide/TransactionTestUtilities.java

@@ -79,6 +79,7 @@ public static BaseTransaction<?> transactionTest(BaseTransaction<?> baseTransact
 
  baseTransaction.lpush(key5, new String[] {value1, value1, value2, value3, value3});
  baseTransaction.llen(key5);
+ baseTransaction.lindex(key5, 0);
  baseTransaction.lrem(key5, 1, value1);
  baseTransaction.ltrim(key5, 1, -1);
  baseTransaction.lrange(key5, 0, -2);
@@ -172,6 +173,7 @@ public static Object[] transactionTestResult() {
  10.5,
  5L,
  5L,
+ value3, // lindex(key5, 0)
  1L,
  OK,
  new String[] {value3, value2},