使用json4s将JSON中的字段替换为新对象

import org.json4s._
import org.json4s.jackson.JsonMethods._

// 创建新对象
case class NewObject(name: String, age: Int)

// JSON字符串
val jsonString = """{"name": "John", "age": 25, "city": "New York"}"""

// 解析JSON
val json = parse(jsonString)

// 替换字段
val transformedJson = json.transformField {
  case JField("name", _) => ("name", JString("Tom"))
  case JField("age", _) => ("age", JInt(30))
  case field => field
}

// 转换为JSON字符串
val result = compact(render(transformedJson))

println(result)