如何遍历java中对象的arrayList？
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【中文标题】如何遍历java中对象的arrayList？【英文标题】：How to iterate over the arrayList of objects in the java? 【发布时间】：2019-04-19 11:33:37 【问题描述】：我已经使用 Angular 将对象数组发送到 Api 以进行后期操作，这与 3 个对象的数组一起使用：
我想在 java 中这样做，所以我在 java 中将类初始化为：
SLDto.java
public class SLDto
private LetterDto letterDto;
private List<DocumentDto> documentDto;
private List<SelectionCustomOfficeDto> selectionCustomOfficeDto;
public SLDto()
//i omitted getters and setters here
LetterDto.java
public class LetterDto
private int clkletter;
private String inOut;
private String inOutNo;
private String inOutDate;
private String letterIssuedSubBy;
private String letterFile;
private String representativeName;
private int assessmentNo;
private int selectionNo;
public LetterDto()
DocumentDto.java
public class DocumentDto
private int docId;
private String docName;
private boolean checked;
public DocumentDto()
SelectionCustomOfficeDto.java
public class SelectionCustomOfficeDto
private int id;
private String fromDate;
private String toDate;
private int consignmentNo;
private int selectionId;
private int customOfficeId;
private String custOfficeName;
private String selectionName;
我需要将客户端对象映射到 Api，所以我使用了该方法：
@PostMapping(value = "/letter/create")
public String postAllOne(@RequestBody SLDto sldto )
//i tried 2ways to see the json data or trace it and assign into
respective objects but i am not getting.I tried
1st method
System.out.println(sldto.getLetterDto()); //Not working
2nd method
for(LetterDto letterDto:sldto.getLetterDto())
//it is not allowing me
return "success";
它不允许我映射为：
如何将 3json 数据分离到各自的对象中？
["inOutNo":"2018-11-12","inOutDate":"2","inOut":"AnnexOne","letterFile":null,"representativeName":null,"assessmentNo":0,"letterIssuedSubBy":null,"selectionNo":8,["docId":1,"docName":"proforma invoice","checked":true,"docId":2,"docName":"Packing list","checked":true],["customOfficeId":"1","fromDate":"2018-11-12","toDate":"2018-11-20","consignmentNo":2,"selectionId":8,"selectionName":"PCS","custOfficeName":"Bhairawa Bhansar"]]
看到的错误是
我收到类似
的错误"DefaultHandlerExceptionResolver : 已解决 [org.springframework.http.converter.HttpMessageNotReadableException： JSON 解析错误：无法反序列化 com.ashwin.springsecurityangular.dto.SLDto out of START_ARRAY token； 嵌套异常是 com.fasterxml.jackson.databind.exc.MismatchedInputException：不能 反序列化 com.ashwin.springsecurityangular.dto.SLDto 的实例 START_ARRAY 令牌”
【问题讨论】：
根据您的班级定义letterDto 不是collection 也不是array。是错字吗？
我收到类似“DefaultHandlerExceptionResolver: Resolved [org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Cannot deserialize instance of com.ashwin.springsecurityangular.dto.SLDto out of START_ARRAY token; 嵌套异常是 com.fasterxml .jackson.databind.exc.MismatchedInputException：无法从 START_ARRAY 令牌中反序列化 com.ashwin.springsecurityangular.dto.SLDto 的实例”
好的 - 您的帖子中似乎存在编译时错误，因此问题是。
你能发布输入json吗
我在页首贴了一张图片，请看
【参考方案1】：
您当前的 POST 方法处理程序需要以下格式的 JSON 对象：
"letterDto" :
"clkletter" : 1,
"inOut" : "Someting",
...
,
"documentDto" : [
"docId" : 1,
"docName" : "Name",
"checked" : true
,
"docId" : 2,
"docName" : "Name 2",
"checked" : false
],
"selectionCustomOfficeDto" : [
"id" : 1,
"fromDate" : "someDate,
...
,
"id" : 2,
"fromDate" : "someDate2,
...
]
但目前，您正在发送一个 JSON 数组：
[
"letterDto" : <letter properties>,
[
<document properties>
,
<document properties>
],
[
<selection custom office properties>
]
]
修复此问题后，您将能够迭代 slDto.getDocumentDto 和 slDto.getSelectionCustomOfficeDto，因为它们是 slDto 对象中包含的唯一集合，因此：
slDto.getSelectionCustomOfficeDto.forEach(s -> doSomething(s));
slDto.getDocumentDto.forEach(d -> doSomething(d));
你可以像这样调用Letter的方法：
slDto.getLetterDto.getId();
【讨论】：
【参考方案2】：您好，请确保您的 JSON 请求如下所示：
"letterDto" :
"clkletter" : 1,
"inOut" : "some-string-value",
"inOutNo" : "some-string-value",
"inOutDate" : "some-string-value",
"letterIssuedSubBy" : "some-string-value",
"letterFile" : "some-string-value",
"representativeName" : "some-string-value",
"assessmentNo" : 1,
"selectionNo" : 1
,
"documentDto" : [
"docId" : 1,
"docName" : "some-doc-name",
"checked" : true
,
"docId" : 2,
"docName" : "some-doc-name",
"checked" : true
,
"docId" : 3,
"docName" : "some-doc-name",
"checked" : true
],
"selectionCustomOfficeDto" : [
"id" : 1,
"fromDate" : "some-date",
"toDate" : "some-date",
"consignmentNo" : 1,
"selectionId" : 1,
"customOfficeId" : 1,
"custOfficeName" : "some-office-name",
"selectionName" : "some-selection-name"
,
"id" : 2,
"fromDate" : "some-date",
"toDate" : "some-date",
"consignmentNo" : 1,
"selectionId" : 1,
"customOfficeId" : 1,
"custOfficeName" : "some-office-name",
"selectionName" : "some-selection-name"
,
"id" : 3,
"fromDate" : "some-date",
"toDate" : "some-date",
"consignmentNo" : 1,
"selectionId" : 1,
"customOfficeId" : 1,
"custOfficeName" : "some-office-name",
"selectionName" : "some-selection-name"
]
另外，在代码块中，
for(LetterDto letterDto:sldto.getLetterDto())
//it is not allowing me
这里sldto.getLetterDto() 返回单个LetterDto Object 而不是List，因此无法进行迭代。
希望对你有帮助！
【讨论】：
【参考方案3】：你应该像下面这样发送json：
"letterDto" : "clkletter": "as" , // your other properties,
"documentDto": ["docId" : 1,"docId" : 2]// your other properties inside json object
"selectionCustomOfficeDto": ["id": 12,"id": 121]// your other properties inside json object
以下示例供您参考，outer 类有List<Inner2>、List<Inner3> 和Inner1
Json 看起来像
"inner1": "f1": "v1","f2": "v2",
"inner2s": ["f3": "v3","f4": "v4","f3": "v5","f4": "v6"],
"inner3s": ["f5": "v7","f6": "v8","f5": "v9","f6": "v10"]
PoJo 类
class Outer
Inner1 inner1;
List<Inner2> inner2s;
List<Inner3> inner3s;
public Inner1 getInner1()
return inner1;
public void setInner1(Inner1 inner1)
this.inner1 = inner1;
public List<Inner2> getInner2s()
return inner2s;
public void setInner2s(List<Inner2> inner2s)
this.inner2s = inner2s;
public List<Inner3> getInner3s()
return inner3s;
public void setInner3s(List<Inner3> inner3s)
this.inner3s = inner3s;
class Inner1
String f1;
String f2;
public String getF1()
return f1;
public void setF1(String f1)
this.f1 = f1;
public String getF2()
return f2;
public void setF2(String f2)
this.f2 = f2;
class Inner2
String f3;
String f4;
public String getF3()
return f3;
public void setF3(String f3)
this.f3 = f3;
public String getF4()
return f4;
public void setF4(String f4)
this.f4 = f4;
class Inner3
String f5;
String f6;
public String getF5()
return f5;
public void setF5(String f5)
this.f5 = f5;
public String getF6()
return f6;
public void setF6(String f6)
this.f6 = f6;
请求映射
@RequestMapping(value="/test",produces=MediaType.APPLICATION_JSON_VALUE,method= RequestMethod.POST)
public String post(@RequestBody Outer outer)
LOGGER.debug("Getting the logged in cutomer details" +outer);
Customer customer1 = new Customer("1", "customer1", "Sample@cust1.com");
LOGGER.info("The customer details are " + customer1);
return "done!!";
【讨论】：
请给反对票的理由，所以，如果有问题，可以学习。谢谢 我让我的数组看起来像这样： 抱歉 - 我没能关注你 很高兴它有帮助。 感谢您付出了太多努力@secret 超级明星，您今天为我提供了太多帮助以上是关于如何遍历java中对象的arrayList？的主要内容，如果未能解决你的问题，请参考以下文章