docs: add example code (#8)

anthropic-java-example/build.gradle.kts

@@ -0,0 +1,13 @@
+plugins {
+    id("java")
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+
+    implementation(project(":anthropic-java"))
+    implementation(project(mapOf("path" to ":anthropic-java-core")))
+}

anthropic-java-example/src/main/java/com/anthropic/example/Main.java

@@ -0,0 +1,49 @@
+package com.anthropic.example;
+
+import com.anthropic.client.AnthropicClient;
+import com.anthropic.client.okhttp.AnthropicOkHttpClient;
+import com.anthropic.core.http.StreamResponse;
+import com.anthropic.models.*;
+
+public final class Main {
+    private Main() {}
+
+    public static void main(String[] args) {
+        AnthropicClient client = AnthropicOkHttpClient.fromEnv();
+        MessageCreateParams.Builder createParamsBuilder = MessageCreateParams.builder()
+                .model(Model.CLAUDE_3_5_SONNET_LATEST)
+                .maxTokens(1000)
+                .addMessage(MessageParam.builder()
+                        .role(MessageParam.Role.USER)
+                        .content(MessageParam.Content.ofString("Tell me a story about building the best SDK!"))
+                        .build());
+
+        // Having a conversation in a loop
+        for (int i = 0; i < 4; i++) {
+            Message message = client.messages().create(createParamsBuilder.build());
+
+            message.content().stream()
+                    .flatMap(contentBlock -> contentBlock.textBlock().stream())
+                    .forEach(textBlock -> System.out.println(textBlock.text()));
+
+            System.out.println("\n-----------------------------------\n");
+
+            createParamsBuilder
+                    .addMessage(message.toParam())
+                    .addMessage(MessageParam.builder()
+                            .role(MessageParam.Role.USER)
+                            .content(MessageParam.Content.ofString("But why???"))
+                            .build());
+        }
+
+        // Streaming example
+        try (StreamResponse<RawMessageStreamEvent> streamResponse = client.messages().createStreaming(createParamsBuilder.build())) {
+            streamResponse.stream()
+                    .flatMap(event -> event.rawContentBlockDeltaEvent().stream())
+                    .flatMap(deltaEvent -> deltaEvent.delta().textDelta().stream())
+                    .forEach(textDelta -> System.out.print(textDelta.text()));
+        } catch (Exception e) {
+            System.out.println(e.getMessage());
+        }
+    }
+}