使用Java对数组进行排序，并在MongoDB中选择字段

import java.util.Arrays;

public class ArraySortExample {
    public static void main(String[] args) {
        int[] array = {5, 2, 8, 1, 9};
        
        // 使用Arrays类的sort()方法对数组进行排序
        Arrays.sort(array);
        
        // 打印排序后的数组
        System.out.println(Arrays.toString(array));
    }
}

import com.mongodb.MongoClient;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoCursor;
import com.mongodb.client.MongoDatabase;
import org.bson.Document;
import com.mongodb.client.model.Projections;

public class MongoDBExample {
    public static void main(String[] args) {
        // 连接MongoDB数据库
        MongoClient mongoClient = new MongoClient("localhost", 27017);
        MongoDatabase database = mongoClient.getDatabase("mydb");
        
        // 获取集合
        MongoCollection<Document> collection = database.getCollection("mycollection");
        
        // 查询并选择需要返回的字段
        Document query = new Document();
        Document projection = new Document();
        projection.put("field1", 1); // 返回field1字段
        projection.put("field2", 1); // 返回field2字段
        projection.put("_id", 0); // 排除_id字段
        MongoCursor<Document> cursor = collection.find(query).projection(projection).iterator();
        
        // 遍历结果
        while (cursor.hasNext()) {
            Document document = cursor.next();
            System.out.println(document.toJson());
        }
        
        // 关闭连接
        mongoClient.close();
    }
}