com.google.firebase.database.DatabaseException：無法將java.lang.String類型的對象轉換爲

Question

從FirebaseDatabase中檢索數據時遇到了一些問題。

我想我已經以正確的方式完成了所有的事情，但仍然會彈出此錯誤並崩潰應用程序。

com.google.firebase.database.DatabaseException: Can't convert object of type java.lang.String to type com.rana.sahaj.myyu.profile.ExtraProfilClass 

ExtraProfilClass

@IgnoreExtraProperties 
public class ExtraProfilClass { 
private String branch; 
private String campus; 
private String course; 
private String gplusURL; 
private String hashname; 
private String picurl; 
private String picurl50DP; 
private String userEmail; 
private String userNAME; 
private String yearFrom; 
private String yearTo; 
public ExtraProfilClass(){ 
    //Empty constructor for firebase 
} 


public ExtraProfilClass(String branch, String campus, String course, String gplusURL, String hashname, String picurl, String picurl50DP, String userEmail, String userNAME, String yearFrom, String yearTo) { 
    this.branch = branch; 
    this.campus = campus; 
    this.course = course; 
    this.gplusURL = gplusURL; 
    this.hashname = hashname; 
    this.picurl = picurl; 
    this.picurl50DP = picurl50DP; 
    this.userEmail = userEmail; 
    this.userNAME = userNAME; 
    this.yearFrom = yearFrom; 
    this.yearTo = yearTo; 
} 

public String getBranch() { 
    return branch; 
} 

public void setBranch(String branch) { 
    this.branch = branch; 
} 

public String getCampus() { 
    return campus; 
} 

public void setCampus(String campus) { 
    this.campus = campus; 
} 

public String getCourse() { 
    return course; 
} 

public void setCourse(String course) { 
    this.course = course; 
} 

public String getGplusURL() { 
    return gplusURL; 
} 

public void setGplusURL(String gplusURL) { 
    this.gplusURL = gplusURL; 
} 

public String getHashname() { 
    return hashname; 
} 

public void setHashname(String hashname) { 
    this.hashname = hashname; 
} 

public String getPicurl() { 
    return picurl; 
} 

public void setPicurl(String picurl) { 
    this.picurl = picurl; 
} 

public String getPicurl50DP() { 
    return picurl50DP; 
} 

public void setPicurl50DP(String picurl50DP) { 
    this.picurl50DP = picurl50DP; 
} 

public String getUserEmail() { 
    return userEmail; 
} 

public void setUserEmail(String userEmail) { 
    this.userEmail = userEmail; 
} 

public String getUserNAME() { 
    return userNAME; 
} 

public void setUserNAME(String userNAME) { 
    this.userNAME = userNAME; 
} 

public String getYearFrom() { 
    return yearFrom; 
} 

public void setYearFrom(String yearFrom) { 
    this.yearFrom = yearFrom; 
} 

public String getYearTo() { 
    return yearTo; 
} 

public void setYearTo(String yearTo) { 
    this.yearTo = yearTo; 
} 
} 

和檢索代碼

@Override 
    public void onChildAdded(DataSnapshot dataSnapshot, String s) { 
     // Map<String, String> msg = (HashMap<String, String>)dataSnapshot.getValue(); 
-->  ExtraProfilClass extraProfilClass=dataSnapshot.getValue(ExtraProfilClass.class); 

    // String userEmail_here=extraProfilClass.getUserEmail(); 
    //  userEmailKey = userEmail_here.substring(0, userEmail_here.length() - 10); 

所以..我解決了這一問題。我沒有使用正確的節點參考，我的壞

（FIX由Shubhank要求）

問題是，我想獲得用戶1的輪廓節點

public static DatabaseReference mFirebaseRef = FirebaseDatabase.getInstance().getReferenceFromUrl(constants.FIREBASE_URL+"app/authGplus/users/"); 

所以我做了什麼是： mFirebaseRef.child(UserToWhichProfileIsNeeded).child("profile").addChildEventListener(listener);

但我打電話addChildEventListener

它已經指子節點，所以我並不需要把.child("profile") refernce時，它會變成這個樣子，

mFirebaseRef.child(UserToWhichProfileIsNeeded).addChildEventListener(listener);

，然後它工作得很好。

Answer 1

第一轉換dataSnapshot到Map<String, Object>然後將其轉換到你的ExtraProfilClass

Map<String, Object> map = (HashMap<String, Object>) dataSnapshot.getValue();