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从Java中获取ArrayList object的值?

[英]Get value from ArrayList object in Java?

I know this is a quite basic question, but after reading some SO posts and google I couldn't understand the issue well, so.我知道这是一个非常基本的问题,但是在阅读了一些 SO 帖子和谷歌之后我无法很好地理解这个问题,所以。

I have a map object data , a System.out.println(data) shows me something like the following on the console:我有一个 map object data ,一个System.out.println(data)在控制台上显示如下内容:

{data=[{engine=engine1, keyword=keyword1, url=url1}, {engine=engine2, keyword=keyword2, url=url2}]}

Also, a data shows me LinkedHashMap@11 size=1 on the console.此外, data在控制台上显示LinkedHashMap@11 size=1

Now I wanted to have the first "engine" key value of the first array of "data", aka engine1 .现在我想拥有第一个“数据”数组的第一个“引擎”键值,也就是engine1

Before that I tried to obtain the first of the array, so I tried the following, but I get errors.在此之前,我尝试获取数组的第一个,所以我尝试了以下操作,但出现错误。

data.get("data")[1]
Cannot evaluate because of compilation error(s): The type of the expression must be an array type but it resolved to Object.

data.get("data").get(1)
Cannot evaluate because of compilation error(s): The method get(int) is undefined for the type Object.

How can I obtain the "engine1" value from "data"?如何从“data”中获取“engine1”的值? Thanks for your help.谢谢你的帮助。

edit:编辑:

The code around it is as shown below.它周围的代码如下所示。 data is declared by Map<String, Object> data . dataMap<String, Object> data声明。

import org.yaml.snakeyaml.Yaml;

~~ 

InputStream inputStream = new FileInputStream(new File("student.yml"));

Yaml yaml = new Yaml();
Map<String, Object> data = yaml.load(inputStream);
System.out.println(data);

(not sure you need this info but just in case, "student.yml" file is as shown below) (不确定您是否需要此信息,但以防万一,“student.yml”文件如下所示)

data: 
  - engine: engine1
    keyword: keyword1
    url: url1
  - engine: engine2
    keyword: keyword2
    url: url2

Updating answer post question edit;更新答案发布问题编辑; Please find below, the solution you want;请在下面找到您想要的解决方案;

import org.yaml.snakeyaml.Yaml;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.util.List;
import java.util.Map;

public class YamlParser {

    public static void main(String[] args) throws FileNotFoundException {

        InputStream inputStream = new FileInputStream(new File("src/main/resources/student.yml"));

        Yaml yaml = new Yaml();
        Map<String, Object> data = yaml.load(inputStream);
        System.out.println(data); // Prints full map
        List<Map<String,String>> eng = (List<Map<String,String>>) data.get("data"); //Casting object to List
        System.out.println(eng.get(0).get("engine")); // Prints the value : engine1
    }
}

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