因此，我正在创建一个 Android Java 类，该类将按照 FirebaseUI 教程中的说明表示来自 Firebase 的数据 here .我必须将 JSON 字段声明为类中的变量。我只是不知道如何声明嵌套字段或我应该使用什么数据类型。
这是我的 Firebase 数据:
{
"Juan Dela Cruz" : {
"ID" : 1,
"Name" : "Juan Dela Cruz",
"Schedule" : [ null, {
"Classroom" : "Lab 1",
"Subject" : "Software Engineering",
"Time_End" : "9:00",
"Time_Start" : "8:00"
}, {
"Classroom" : "Lab 2",
"Subject" : "Cisco",
"Time_End" : "12:00",
"Time_Start" : "10:00"
} ],
"Status" : "In"
}
}
更新 我在这里为 Schedule 添加了一个单独的类:
public class FacultyList {
private String Name;
private String ID;
private String Status;
private Sched Schedule;
public FacultyList(){
}
public FacultyList(String Name, String ID, String Status, Sched Schedule ){
this.Name = Name;
this.ID = ID;
this.Status = Status;
this.Schedule = Schedule;
}
public String getName(){
return Name;
}
public String getID(){
return ID;
}
public Sched getSchedule(){
return Schedule;
}
public String getStatus(){
return Status;
}
public class Sched Schedule {
private String Classroom;
private String Subject;
private String Time_End;
private String Time_Start;
public Sched(){
}
public Sched(String Classroom, String Subject, String Time_End, String Time_Start){
this.Classroom = Classroom;
this.Subject= Subject;
this.Time_End = Time_End;
this.Time_Start = Time_Start;
}
public String getClassroom(){
return Classroom;
}
public String getSubject(){
return Subject;
}
public String getTime_Start(){
return Time_Start;
}
public String getTime_End(){
return Time_End;
}
}
我的主要 Activity 类中的代码 fragment :
public void fetchFaculty(){
Firebase ref = new Firebase("https://infotrack.firebaseio.com/infotrack/faculty");
GridView gridView = (GridView) findViewById(R.id.grid);
FirebaseListAdapter<FacultyList> listFaculty = new FirebaseListAdapter<FacultyList>(this,FacultyList.class, R.layout.layout_faculty, ref) {
@Override
protected void populateView(View view,FacultyList faculty) {
String ID = faculty.getID();
String Status = faculty.getStatus();
ImageView image = (ImageView) view.findViewById(R.id.imageFaculty);
if(Status.equalsIgnoreCase("In")) {
Picasso.with(getApplicationContext()).load("http://infotrack.kimfeliciano.xyz/images/" + id + ".png").fit().centerCrop().into(image);
} else {
Picasso.with(getApplicationContext()).load("http://infotrack.kimfeliciano.xyz/images/" + id + "x.png").fit().centerCrop().into(image);
}
((TextView) view.findViewById(R.id.txtName)).setText(faculty.getName());
((TextView) view.findViewById(R.id.txtClassroom)).setText(faculty.getSchedule().getClassroom());
}
};
gridView.setAdapter(listFaculty);
}
当我不从 Schedule 类查询数据时，我的代码工作正常。由于我试图从“Schedule”类中查询“classroom”，因此出现以下错误:
FATAL EXCEPTION: main Process: xyz.kimfeliciano.infotrack.infotrack, PID: 25782 java.lang.NullPointerException at com.fasterxml.jackson.databind.deser.impl.BeanPropertyMap.find(BeanPropertyMap.java:216) at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:292) at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:121) at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2888) at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2034) at com.firebase.client.DataSnapshot.getValue(DataSnapshot.java:183) at com.firebase.ui.FirebaseListAdapter.getView(FirebaseListAdapter.java:130) at android.widget.AbsListView.obtainView(AbsListView.java:2263) at android.widget.GridView.onMeasure(GridView.java:1044) at android.view.View.measure(View.java:16558) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125) at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404) at android.widget.LinearLayout.measureVertical(LinearLayout.java:695) at android.widget.LinearLayout.onMeasure(LinearLayout.java:588) at android.view.View.measure(View.java:16558) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125) at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) at android.view.View.measure(View.java:16558) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125) at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404) at android.widget.LinearLayout.measureVertical(LinearLayout.java:695) at android.widget.LinearLayout.onMeasure(LinearLayout.java:588) at android.view.View.measure(View.java:16558) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125) at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2291) at android.view.View.measure(View.java:16558) at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1923) at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1120) at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1302) at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1007) at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5677) at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761) at android.view.Choreographer.doCallbacks(Choreographer.java:574) at android.view.Choreographer.doFrame(Choreographer.java:544) at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747) at android.os.Handler.handleCallback(Handler.java:733) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:136) at android.app.ActivityThread.main(ActivityThread.java:5021) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:515) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:827) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:643) at dalvik.system.NativeStart.main(Native Method)
最佳答案
这是你的根对象
public class MyJsonPojo {
private JuanDelaCruz JuanDelaCruz;
/**
*
* @return
* The JuanDelaCruz
*/
public JuanDelaCruz getJuanDelaCruz() {
return JuanDelaCruz;
}
/**
*
* @param JuanDelaCruz
* The Juan Dela Cruz
*/
public void setJuanDelaCruz(JuanDelaCruz JuanDelaCruz) {
this.JuanDelaCruz = JuanDelaCruz;
}
}
这是您的 juan dela cruz 对象:
import java.util.ArrayList;
import java.util.List;
public class JuanDelaCruz {
private int ID;
private String Name;
private List<Schedule> Schedule = new ArrayList<Schedule>();
private String Status;
/**
*
* @return
* The ID
*/
public int getID() {
return ID;
}
/**
*
* @param ID
* The ID
*/
public void setID(int ID) {
this.ID = ID;
}
/**
*
* @return
* The Name
*/
public String getName() {
return Name;
}
/**
*
* @param Name
* The Name
*/
public void setName(String Name) {
this.Name = Name;
}
/**
*
* @return
* The Schedule
*/
public List<Schedule> getSchedule() {
return Schedule;
}
/**
*
* @param Schedule
* The Schedule
*/
public void setSchedule(List<Schedule> Schedule) {
this.Schedule = Schedule;
}
/**
*
* @return
* The Status
*/
public String getStatus() {
return Status;
}
/**
*
* @param Status
* The Status
*/
public void setStatus(String Status) {
this.Status = Status;
}
}
这是您的 Schedule 对象类
public class Schedule {
private String Classroom;
private String Subject;
private String TimeEnd;
private String TimeStart;
/**
*
* @return
* The Classroom
*/
public String getClassroom() {
return Classroom;
}
/**
*
* @param Classroom
* The Classroom
*/
public void setClassroom(String Classroom) {
this.Classroom = Classroom;
}
/**
*
* @return
* The Subject
*/
public String getSubject() {
return Subject;
}
/**
*
* @param Subject
* The Subject
*/
public void setSubject(String Subject) {
this.Subject = Subject;
}
/**
*
* @return
* The TimeEnd
*/
public String getTimeEnd() {
return TimeEnd;
}
/**
*
* @param TimeEnd
* The Time_End
*/
public void setTimeEnd(String TimeEnd) {
this.TimeEnd = TimeEnd;
}
/**
*
* @return
* The TimeStart
*/
public String getTimeStart() {
return TimeStart;
}
/**
*
* @param TimeStart
* The Time_Start
*/
public void setTimeStart(String TimeStart) {
this.TimeStart = TimeStart;
}
}
我使用 pojo 生成器网站生成了所有这些 pojo，例如 this one
关于java - 使用 FirebaseUI 在 Android TextView 中绑定(bind)嵌套的 JSON，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/34248906/