samples: add quickstart (#82)

Author: Mahina Kaholokula

servicedirectory/snippets/snippets/src/main/java/com/example/servicedirectory/Quickstart.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2020 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.servicedirectory;
+
+// [START servicedirectory_quickstart]
+
+import com.google.cloud.servicedirectory.v1beta1.LocationName;
+import com.google.cloud.servicedirectory.v1beta1.Namespace;
+import com.google.cloud.servicedirectory.v1beta1.RegistrationServiceClient;
+import com.google.cloud.servicedirectory.v1beta1.RegistrationServiceClient.ListNamespacesPagedResponse;
+import java.io.IOException;
+
+public class Quickstart {
+
+  public static void quickstart() throws IOException {
+    // TODO(developer): Replace these variables before running the sample.
+    String projectId = "your-project-id";
+    String locationId = "your-region";
+    quickstart(projectId, locationId);
+  }
+
+  public static void quickstart(String projectId, String locationId) throws IOException {
+    // Initialize client that will be used to send requests. This client only needs to be created
+    // once, and can be reused for multiple requests. After completing all of your requests, call
+    // the "close" method on the client to safely clean up any remaining background resources.
+    try (RegistrationServiceClient client = RegistrationServiceClient.create()) {
+
+      // The project and location that hold the namespace to list.
+      LocationName parent = LocationName.of(projectId, locationId);
+
+      // Call the API.
+      ListNamespacesPagedResponse response = client.listNamespaces(parent);
+
+      // Iterate over each namespace and print its name.
+      System.out.println("Namespaces:");
+      for (Namespace namespace : response.iterateAll()) {
+        System.out.println(namespace.getName());
+      }
+    }
+  }
+}
+// [END servicedirectory_quickstart]