我正在尝试使用GSON将JSON对象转换为POJO。
JSON字串
[ { "automation_project": { "user_id": null, "name": "Untitled Project", "updated_at": "2015-06-16T19:39:42Z", "group_id": 764496, "created_at": "2014-11-23T01:01:59Z", "id": 16214 } }, { "automation_project": { "user_id": null, "name": "newintropage", "updated_at": "2015-06-16T21:20:47Z", "group_id": 764496, "created_at": "2015-06-16T20:39:04Z", "id": 29501 } } ]
与GSON一起使用的AutomationProjectsList类
public class AutomationProjectsList { private List<AutomationProject> automationProject = new ArrayList<AutomationProject>(); public List<AutomationProject> getAutomationProject() { return automationProject; } public void setAutomationProject(List<AutomationProject> automationProject) { this.automationProject = automationProject; } @Override public String toString() { return "AutomationProjectsList [automationProject=" + automationProject + "]"; }}
自动化项目POJO
public class AutomationProject { private Object userId; private Integer groupId; private Integer id; private String name; private String updatedAt; private String createdAt; public Object getUserId() { return userId; } public void setUserId(Object userId) { this.userId = userId; } public Integer getGroupId() { return groupId; } public void setGroupId(Integer groupId) { this.groupId = groupId; } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getUpdatedAt() { return updatedAt; } public void setUpdatedAt(String updatedAt) { this.updatedAt = updatedAt; } public String getCreatedAt() { return createdAt; } public void setCreatedAt(String createdAt) { this.createdAt = createdAt; }}
我正在使用的代码
JSONArray jsonArray =新的JSONArray(response.getEntity(String.class));
for(int i = 0; i < jsonArray.length(); i++){ if(jsonArray.get(i) instanceof JSONObject){ JSONObject jsnObj = (JSONObject)jsonArray.get(i); AutomationProjectsList obj = new Gson().fromJson(jsnObj.toString(), AutomationProjectsList.class); System.out.println(obj.getAutomationProject().get(0).getId()); } }
但是它给出了一个例外:
Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 0, Size: 0 at java.util.ArrayList.rangeCheck(ArrayList.java:653) at java.util.ArrayList.get(ArrayList.java:429) at br.usp.icmc.teste.ConnectionRestClient.getBrowserStackProjects(ConnectionRestClient.java:74) at br.usp.icmc.teste.TestePrincipal.main(TestePrincipal.java:9)
为什么会收到IndexOutOfBoundsException异常?我哪里错了?
您的课程或JSON不正确。我建议您使用JSON。与POJO类匹配的JSON为:
{ "automationProjects":[ { "user_id": null, "name": "Untitled Project", "updated_at": "2015-06-16T19:39:42Z", "group_id": 764496, "created_at": "2014-11-23T01:01:59Z", "id": 16214 }, { "user_id": null, "name": "newintropage", "updated_at": "2015-06-16T21:20:47Z", "group_id": 764496, "created_at": "2015-06-16T20:39:04Z", "id": 29501 } ] }
请注意,我为列表使用了名称AutomationProjects,因为它更有意义,因此您的类将是:
public class AutomationProjectsList { private List<AutomationProject> automationProjects = new ArrayList<AutomationProject>(); public List<AutomationProject> getAutomationProjects() { return automationProjects; } public void setAutomationProjects(List<AutomationProject> automationProjects) { this.automationProjects = automationProjects; } @Override public String toString() { return "AutomationProjectsList [automationProject=" + automationProject + "]"; } }
最后将JSON转换为AutomationProjectsList对象:
AutomationProjectsList projectsList = new Gson().fromJson(jsonArray.toString(), AutomationProjectsList.class);
然后,如果要记录每个项目:
for(AutomationProject project : projectsList.automationProjects){ System.out.println(porject.getId()); }
总之,您的代码似乎存在以下问题:
您有列表列表还是仅一个项目列表?如果列表只是一个,为什么要jsonArray像它的子对象就是列表一样进行迭代呢?
jsonArray
如果您在JSON上正确建模您的类,则无需迭代JSON即可获取对象
您发布的JSON非常奇怪,并且不易与Gson一起使用,这是一项要求还是可以根据需要进行编辑?
希望这可以帮助
既然您声明无法更改所获取的JSON,那么它将变得更加复杂,但是一切都取决于对JSON格式的类进行建模。因此,让我们从这个JSON开始:
现在,这很讨厌,但是让我们看看这里有什么:我们有一个具有单个属性的未命名对象数组,"automationProject"这是我们的实际AutomationProject对象。因此,就结构而言,它是包装实际AutomationProject的对象列表。
"automationProject"
因此,您将需要摆脱AutomationProjectList并使用看起来更有意义的AutomationProjectWrapper对其进行更改:
public class AutomationProjectsWrapper { private AutomationProject automation_project = new AutomationProject(); public AutomationProject getAutomationProject() { return automation_project; } public void setAutomationProject(AutomationProject automationProject) { this.automation_project = automationProject; } @Override public String toString() { return "AutomationProjectsList [automationProject=" + automation_project + "]"; } }
请参阅此类等同于JSON对象:
{ "automation_project": { "user_id": null, "name": "Untitled Project", "updated_at": "2015-06-16T19:39:42Z", "group_id": 764496, "created_at": "2014-11-23T01:01:59Z", "id": 16214 } }
最终,您将得到一个数组包装对象,如jsonArray,因此您可以编写:
AutomationProjectWrapper[] projectsList = new Gson().fromJson(jsonArray.toString(), AutomationProjectWrapper[].class);
然后记录您的对象:
for(AutomationProjectWrapper wrapper : projectsList){ System.out.println(wrapper.getAutomationProject().getId()); }
抱歉,该错误在AutomationProjectWrapper课堂上AutomationProject应命名为automation_project。已在上面的代码中修复。
AutomationProjectWrapper
AutomationProject
automation_project