写一段java代码，将对象转为字符串

可以使用Java提供的ObjectMapper类来将Java对象转换为JSON字符串。需要引入Jackson库，以下是示例代码：

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class ObjectToString {
    public static void main(String[] args) {
        // 创建一个Java对象
        Person person = new Person("Tom", 18);

        // 创建ObjectMapper对象
        ObjectMapper objectMapper = new ObjectMapper();

        // 将Java对象转换为JSON字符串
        try {
            String jsonString = objectMapper.writeValueAsString(person);
            System.out.println(jsonString);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
    }

    static class Person {
        private String name;
        private int age;

        public Person(String name, int age) {
            this.name = name;
            this.age = age;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public int getAge() {
            return age;
        }

        public void setAge(int age) {
            this.age = age;
        }
    }
}

输出结果为：

{"name":"Tom","age":18}