用戶登錄后，我試圖在主菜單屏幕的列表視圖上顯示Firebase實時數據庫中的數據。該應用程序正在運行，但未顯示數據。這是我數據庫中的數據現在為代碼。MainMenu.java在OnCreate（）上調用此函數。 public void makeItem () { lv = findViewById(R.id.listView); db = FirebaseDatabase.getInstance().getReference(); helper = new FirebaseHelper(db); adapter= new AdapterItem(this,helper.retrive()); lv.setAdapter(adapter); } CustomListAdapter.javapublic class CustomListAdapter{ private String ItemName; private String Quantity; private String SerialNo; private String SupplierName; private String SupplierEmail; private String SupplierPhone; public CustomListAdapter(){ } public CustomListAdapter (String ItemName,String Quantity,String SerialNo,String SupplierName,String SupplierEmail,String SupplierPhone) { this.ItemName = ItemName; this.Quantity = Quantity; this.SerialNo = SerialNo; this.SupplierName = SupplierName; this.SupplierEmail = SupplierEmail; this.SupplierPhone = SupplierPhone; } public void setItemName (String ItemName) { this.ItemName = ItemName; } public String getItemName () { return ItemName; } public void setQuantity (String Quantity) { this.Quantity = Quantity; } public String getQuantity () { return Quantity; } public void setSerialNo (String SerialNo) { this.SerialNo = SerialNo; } public String getSerialNo () { return SerialNo; } public void setSupplierName (String SupplierName) { this.SupplierName = SupplierName; } public String getSupplierName() { return SupplierName; } public void setSupplierEmail (String SupplierEmail) { this.SupplierEmail = SupplierEmail; } public String getSupplierEmail() { return SupplierEmail; } public void setSupplierPhone (String SupplierPhone) { this.SupplierPhone = SupplierPhone; }
1 回答
慕桂英4014372
TA貢獻1871條經驗 獲得超13個贊
代碼中的問題在于，您的CustomListAdapter類中有一個名為的字段，ItemName但您使用的是一個名為getter的getter getItemName()，這是不正確的，因為Firebase在數據庫中查找的名為itemNameand not 的字段ItemName?？吹叫慽字母還是大寫字母I？
有兩種方法可以解決此問題。第一個方法是根據Java命名約定重命名字段來更改模型類。因此，您的模型類應如下所示：
public class CustomListAdapter {
private String itemName, quantity, serialNo, supplierName, supplierEmail, supplierPhone;
public CustomListAdapter() {}
public CustomListAdapter(String itemName, String quantity, String serialNo, String supplierName, String supplierEmail, String supplierPhone) {
this.itemName = itemName;
this.quantity = quantity;
this.serialNo = serialNo;
this.supplierName = supplierName;
this.supplierEmail = supplierEmail;
this.supplierPhone = supplierPhone;
}
public String getItemName() { return itemName; }
public String getQuantity() { return quantity; }
public String getSerialNo() { return serialNo; }
public String getSupplierName() { return supplierName; }
public String getSupplierEmail() { return supplierEmail; }
public String getSupplierPhone() { return supplierPhone; }
}
在此示例中看到，存在private字段和公共獲取器。還有一個更簡單的解決方案，可以像這樣直接在公共字段上設置值：
public class CustomListAdapter {
public String itemName, quantity, serialNo, supplierName, supplierEmail, supplierPhone;
}
現在，只需刪除當前數據，然后使用正確的名稱再次添加即可。僅在測試階段，此解決方案才有效。
還有第二種方法，即使用annotations。因此，如果您更喜歡使用私有字段和公共getter，則應僅在getter之前使用PropertyName批注。因此，您的CustomListAdapter課程應如下所示：
public class CustomListAdapter {
private String ItemName;
private String Quantity;
private String SerialNo;
private String SupplierName;
private String SupplierEmail;
private String SupplierPhone;
public CustomListAdapter() {}
public CustomListAdapter(String itemName, String quantity, String serialNo, String supplierName, String supplierEmail, String supplierPhone) {
ItemName = itemName;
Quantity = quantity;
SerialNo = serialNo;
SupplierName = supplierName;
SupplierEmail = supplierEmail;
SupplierPhone = supplierPhone;
}
@PropertyName("ItemName")
public String getItemName() { return ItemName; }
@PropertyName("Quantity")
public String getQuantity() { return Quantity; }
@PropertyName("SerialNo")
public String getSerialNo() { return SerialNo; }
@PropertyName("SupplierName")
public String getSupplierName() { return SupplierName; }
@PropertyName("SupplierEmail")
public String getSupplierEmail() { return SupplierEmail; }
@PropertyName("SupplierPhone")
public String getSupplierPhone() { return SupplierPhone; }
}
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