Added java sample for chat

Author: anandmali

java/src/main/java/com/example/gemini/ChatSession.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2025 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
+ *
+ *      https://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.gemini;
+
+import com.google.genai.Chat;
+import com.google.genai.Client;
+import com.google.genai.types.Content;
+import com.google.genai.types.GenerateContentConfig;
+import com.google.genai.types.GenerateContentResponse;
+import com.google.genai.types.Part;
+
+import java.util.Collections;
+import java.util.List;
+
+public class ChatSession {
+    public static List<GenerateContentResponse> chat() {
+        // [START chat]
+        Client client = new Client();
+
+        Content userContent = Content.fromParts(Part.fromText("Hello"));
+        Content modelContent =
+                Content.builder()
+                        .role("model")
+                        .parts(
+                                Collections.singletonList(
+                                        Part.fromText("Great to meet you. What would you like to know?")
+                                )
+                        ).build();
+
+        Chat chat = client.chats.create(
+                "gemini-2.0-flash",
+                GenerateContentConfig.builder()
+                        .systemInstruction(userContent)
+                        .systemInstruction(modelContent)
+                        .build()
+        );
+
+        GenerateContentResponse response1 = chat.sendMessage("I have 2 dogs in my house.");
+        System.out.println(response1.text());
+
+        GenerateContentResponse response2 = chat.sendMessage("How many paws are in my house?");
+        System.out.println(response2.text());
+
+        // [END chat]
+        return List.of(response1, response2);
+    }
+}

java/src/test/java/com/example/gemini/ChatSessionTest.java

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+/*
+ * Copyright 2025 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
+ *
+ *      https://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.gemini;
+
+import com.google.genai.types.GenerateContentResponse;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+public class ChatSessionTest {
+    @Test
+    public void test_chat() {
+        List<GenerateContentResponse> chatResponses = assertDoesNotThrow(ChatSession::chat,
+                "chat returned an error");
+
+        for (GenerateContentResponse response : chatResponses) {
+            assertNotNull(response, "Response should not be null");
+            assertNotNull(response.text(), "Response text should not be null");
+            assertFalse(response.text().trim().isEmpty(), "Response text should not be empty");
+        }
+    }
+}