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# Java 示例
<a name="examples-java"></a>

以下 Java 示例演示了用户如何开始生成内嵌代码建议。这些说明性示例向您展示了如何为自己的项目触发编码助手。以下大多数示例适用于其他语言：
+ [生成类和函数](#classes-java)
+ [文件代码](#code-java)
+ [生成算法](#algorithms-java)
+ [生成单元测试](#tests-java)

## 生成类和函数
<a name="classes-java"></a>

要生成全部或部分类实现，请使用代码注释。该评论描述了该班的意图。从简单开始，必要时添加更多细节。生成类后，可以继续在其框架内生成函数。

在撰写评论时，最好使用该语言的注释结构。In Java，这是`/** */`*。*

输入: 

```
/**
 * DocumentReader class. has a name, children and optional parent. 
 * Includes I/O functions to read and
 * write document
 */
```

输出：

```
/**
 * DocumentReader class. has a name, children and optional parent. 
 * Includes I/O functions to read and
 * write document
 */
import java.util.ArrayList;
public class DocumentReader {
    private String name;
    private DocumentReader parent;
    private ArrayList<DocumentReader> children;

    /**
     * Constructor
     * @param name name of the document
     * @param parent parent of the document
     */
    public DocumentReader(String name, DocumentReader parent) {
        this.name = name;
        this.parent = parent;
        this.children = new ArrayList<>();
    }

    /**
     * Constructor
     * @param name name of the document
     */
    public DocumentReader(String name) {
        this(name, null);
    }
    /**
     * Getter for name
     * @return name of the document
     */
    public String getName() {
        return name;
    }

    /**
     * Getter for parent
     * @return parent of the document
     */
    public DocumentReader getParent() {
        return parent;
    }

    /**
     * Getter for children
     * @return children of the document
     */
    public ArrayList<DocumentReader> getChildren() {
        return children;
    }

    /**
     * Adds a child to the document
     * @param child child to be added
     */
    public void addChild(DocumentReader child) {
        children.add(child);
    }

    /**
     * Removes a child from the document
     * @param child child to be removed
     */
    public void removeChild(DocumentReader child) {
        children.remove(child);
    }
}
```

现在有了初始类，可以生成一个带有额外注释的附加函数。

输入:

```
/**
* function to read document from local directory path
* and print first line of document
*/
```

输出：

```
/**
 * function to read document from local directory path
 * and print first line of document
 */
public void readDocument() {
    try {
        BufferedReader reader = new BufferedReader(new FileReader(name));
        String line = reader.readLine();
        System.out.println(line);
        reader.close();
    } catch (IOException e) {
        System.out.println("Error reading document: " + e.getMessage());
    }
}
```

## 文件代码
<a name="code-java"></a>

依靠内联文档，缩短编写代码的时间。添加一个 Java 评论中断`/* */`。

输入: 

```
import java.util.function.Function;

public class S3Utils {
    /* 
     * <place cursor here>
    */
    public static Function<String, String> generateS3Function(String bucketName, String region) {
        return (String key) -> {
            String url = generateS3Url(bucketName, key, region);
            return url;
        };
    }
}
```

如果未进行内联生成，请在将光标放在所需文档的位置后执行 Amazon Q Developer 内联建议。

输出：

```
import java.util.function.Function;

public class S3Utils {
    /* 
     * Generate a function that returns the S3 URL for a given key
     * @param bucketName the name of the bucket
     * @param region the region of the bucket
     * @return the function that generates the S3 URL
    */
    public static Function<String, String> generateS3Function(String bucketName, String region) {
        return (String key) -> {
            String url = generateS3Url(bucketName, key, region);
            return url;
        };
    }
}
```

要更简单地解释代码（类、函数或脚本元素），请使用正向字符 (`//`)，这些字符策略性地放在要添加文档的代码部分之前。

输入:

```
// 
public class S3Utils {
    /* 
     * Generate a function that returns the S3 URL for a given key
     * @param bucketName the name of the bucket
     * @param region the region of the bucket
     * @return the function that generates the S3 URL
    */
    public static Function<String, String> generateS3Function(String bucketName, String region) {
        return (String key) -> {
            String url = generateS3Url(bucketName, key, region);
            return url;
        };
    }
}
```

输出：

```
// This class is used to generate a function that returns the S3 URL for a given key
public class S3Utils {
    /* 
     * Generate a function that returns the S3 URL for a given key
     * @param bucketName the name of the bucket
     * @param region the region of the bucket
     * @return the function that generates the S3 URL
    */
    public static Function<String, String> generateS3Function(String bucketName, String region) {
        return (String key) -> {
            String url = generateS3Url(bucketName, key, region);
            return url;
        };
    }
}
```

## 生成算法
<a name="algorithms-java"></a>

Amazon Q 开发者可以生成常用的算法，尤其是与之相关的算法 AWS SDKs。在你的脚本中，添加一个提示来指定你想要的函数。

此示例生成用户名密钥到命名值的哈希映射，然后使用冒泡排序算法生成排序函数。

输入:

```
import java.util.HashMap;
public class SortList {

    // generate key value pair hash map for 
    // user id and name
    public static HashMap<Integer, String> getUserIdNameMap() {
        HashMap<Integer, String> userIdNameMap = new HashMap<Integer, String>();
        userIdNameMap.put(1, "Amit");
        userIdNameMap.put(2, "Rahul");
        userIdNameMap.put(3, "Vijay");
        userIdNameMap.put(4, "Raj");
        userIdNameMap.put(5, "Kumar");
        return userIdNameMap;
    }

    /*
    * Create function to sort UserIdName map by name alphabetically using bubble sort
    */ 
    
    
}
```

输出：

```
/*
* Create function to sort UserIdName map by name alphabetically using bubble sort
*/ 
public static HashMap<Integer, String> sortUserIdNameMap(HashMap<Integer, String> userIdNameMap) {
    int size = userIdNameMap.size();
    for (int i = 0; i < size; i++) {
        for (int j = i + 1; j < size; j++) {
            if (userIdNameMap.get(i).compareTo(userIdNameMap.get(j)) > 0) {
                String temp = userIdNameMap.get(i);
                userIdNameMap.put(i, userIdNameMap.get(j));
                userIdNameMap.put(j, temp);
            }
        }
    }
    return userIdNameMap;
}
```

此外，用户还可以为标准程序创建提示。在此示例中，用户创建了将哈希映射存储到 Amazon DynamoDB 表的提示。在脚本的开头，用户添加了添加 DynamoDB 的提示 Java 库可帮助为 Amazon Q 开发者提供更多背景信息。

输入:

```
// add libraries for Amazon DynamoDB
import com.amazonaws.services.dynamodbv2.AmazonDynamoDB;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClientBuilder;

     /*
     * Store sorted UserIdName map into Amazon DynamoDB table named users
     */
```

输出：

```
// add libraries for Amazon DynamoDB
import com.amazonaws.services.dynamodbv2.AmazonDynamoDB;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClientBuilder;

     /*
     * Store sorted UserIdName map into Amazon DynamoDB table named users
     */
    public static void storeSortedUserIdNameMap(HashMap<Integer, String> userIdNameMap) {
        // create Amazon DynamoDB client
        AmazonDynamoDB client = AmazonDynamoDBClientBuilder.defaultClient();

        // store sorted UserIdName map into Amazon DynamoDB table named users
        for (int userId : userIdNameMap.keySet()) {
            String name = userIdNameMap.get(userId);
            client.putItem("users", new HashMap<String, Object>() {{
                put("userId", userId);
                put("name", name);
            }});
        }
    }
```

## 生成单元测试
<a name="tests-java"></a>

通过内嵌评论，Amazon Q Developer 可以生成单元测试来执行断言和其他 JUnit 测试。在此示例中，用户首先要求 Amazon Q 生成适用的库 JUnit 以设置测试脚本的上下文。接下来，用户创建一个公共类，后面是声明符和注释字符串。

输入:

```
// import libraries for java unit tests
import org.junit.Test;
import static org.junit.Assert.*;

public class UnitTests {

    @Test 
    /*
     * Create unit test for getUserIdNameMap
     */  
}
```

输出：

```
@Test 
/*
* Create unit test for getUserIdNameMap
*/
public void testGetUserIdNameMap() {
    // create a new instance of the UserIdNameMap class
    UserIdNameMap userIdNameMap = new UserIdNameMap();

    // create a new instance of the User class
    User user = new User("John", "Doe");

    // add the user to the map
    userIdNameMap.addUser(user);

    // get the user from the map
    User retrievedUser = userIdNameMap.getUser("John");

    // assert that the retrieved user is the same as the user added to the map
    assertEquals(user, retrievedUser);
}
```

此外，在用户与 Amazon Q Developer 之间的聊天中，它会根据用户的代码输入提示建议并生成单元测试。有关更多信息，请参阅[聊天示例](examples-chat.md)。