，您还需要添加一个空构造函数
我一直在研究Android应用程序以进行本地化。该数据库连接到Firebase，以实时跟踪用户。在实施注册表格时，我经历了此错误，但我永远无法摆脱它。每当我尝试注册为学生或老师时，申请崩溃。我提到了这一点，但也没有帮助我。这是我的代码
package com.example.appla.iattended;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import com.firebase.client.Firebase;
public class SignUpActivity extends AppCompatActivity {
EditText email, password,id, confirmPassword;
String str_email, str_password,str_id, str_confirmPassword;
Boolean email_verified, password_verified, isTA, id_verified;
Firebase ref = new Firebase("https://yattend-755ad.firebaseio.com/");
Button signUp;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_signup);
Firebase.setAndroidContext(this);
email = (EditText) findViewById(R.id.txt_signup_email);
password = (EditText) findViewById(R.id.txt_signup_password);
confirmPassword = (EditText) findViewById(R.id.txt_signup_confirm_password);
id = (EditText) findViewById(R.id.txt_signup_id);
email.setOnFocusChangeListener(new View.OnFocusChangeListener() {
public void onFocusChange(View v, boolean hasFocus) {
if (hasFocus)
email.setHint("");
else
email.setHint("GUC email");
}
});
password.setOnFocusChangeListener(new View.OnFocusChangeListener() {
public void onFocusChange(View v, boolean hasFocus) {
if (hasFocus)
password.setHint("");
else
password.setHint("Password");
}
});
confirmPassword.setOnFocusChangeListener(new View.OnFocusChangeListener() {
public void onFocusChange(View v, boolean hasFocus) {
if (hasFocus)
confirmPassword.setHint("");
else
confirmPassword.setHint("Confirm Password");
}
});
id.setOnFocusChangeListener(new View.OnFocusChangeListener() {
public void onFocusChange(View v, boolean hasFocus) {
if (hasFocus)
id.setHint("");
else
id.setHint("XX-XXXXX");
}
});
signUp = (Button) findViewById(R.id.btn_login);
signUp.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//generate strings
str_email = email.getText().toString();
str_password = password.getText().toString();
str_confirmPassword = confirmPassword.getText().toString();
str_id = id.getText().toString();
//checking password
if(str_password.equals(str_confirmPassword)){
password_verified = true;
}else{
password_verified = false;
Toast.makeText(SignUpActivity.this,
"Passwords do not match, please try again.", Toast.LENGTH_LONG).show();
}
//checking email
if(str_email.endsWith("@student.guc.edu.eg")){
email_verified = true;
isTA =false;
}else if(str_email.endsWith("@guc.edu.eg")) {
email_verified = true;
isTA=true;
}else{
email_verified = false;
Toast.makeText(SignUpActivity.this,
"Incorrect Email. Please use your GUC email.", Toast.LENGTH_LONG).show();
}
//checking id
if(str_id.contains("-") && str_id.length() > 4){
id_verified =true;
}else if (str_id.equals("") && isTA) {
id_verified = true;
} else{
id_verified =false;
Toast.makeText(SignUpActivity.this,
"Please insert GUC ID or if TA, leave blank.", Toast.LENGTH_LONG).show();
}
//To firebase
if(email_verified && password_verified && id_verified){
//Insert
User user = new User(str_email,str_password,str_id,isTA);
Firebase newRef = ref.child("Users").push();
newRef.setValue(user);
if(isTA){
//Redirect to TA's page
Intent myIntent = new Intent(SignUpActivity.this, StartSessionActivity.class);
SignUpActivity.this.startActivity(myIntent);
}else{
//Redirect to students page
Intent myIntent = new Intent(SignUpActivity.this, StudentActivity.class);
SignUpActivity.this.startActivity(myIntent);
}
}
}
});
}
}
这是用户类：
package com.example.appla.iattended;
public class User {
String email, password,id;
Boolean isTa;
public User(String email, String password, String id,Boolean isTa){
this.email=email;
this.password=password;
this.id=id;
this.isTa=isTa;
}
}
，每当我按下按钮寄存器
时，这是我生成的日志FATAL EXCEPTION: main
com.firebase.client.FirebaseException: Failed to parse to snapshot
at com.firebase.client.Firebase.setValueInternal(Firebase.java:347)
at com.firebase.client.Firebase.setValue(Firebase.java:238)
at com.example.appla.iattended.SignUpActivity$5.onClick(SignUpActivity.java:122)
at android.view.View.performClick(View.java:4211)
at android.view.View$PerformClick.run(View.java:17267)
at android.os.Handler.handleCallback(Handler.java:615)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4898)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1006)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.IllegalArgumentException: No serializer found for class com.example.appla.iattended.User and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) )
at com.fasterxml.jackson.databind.ObjectMapper._convert(ObjectMapper.java:2615)
at com.fasterxml.jackson.databind.ObjectMapper.convertValue(ObjectMapper.java:2542)
at com.firebase.client.Firebase.setValueInternal(Firebase.java:336)
at com.firebase.client.Firebase.setValue(Firebase.java:238)
at com.example.appla.iattended.SignUpActivity$5.onClick(SignUpActivity.java:122)
at android.view.View.performClick(View.java:4211)
at android.view.View$PerformClick.run(View.java:17267)
at android.os.Handler.handleCallback(Handler.java:615)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4898)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1006)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773)
at dalvik.system.NativeStart.main(Native Method)
Caused by: com.fasterxml.jackson.databind.JsonMappingException: No serializer found for class com.example.appla.iattended.User and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) )
at com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.failForEmpty(UnknownSerializer.java:59)
at com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.serialize(UnknownSerializer.java:26)
at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:118)
at com.fasterxml.jackson.databind.ObjectMapper._convert(ObjectMapper.java:2593)
at com.fasterxml.jackson.databind.ObjectMapper.convertValue(ObjectMapper.java:2542)
at com.firebase.client.Firebase.setValueInternal(Firebase.java:336)
at com.firebase.client.Firebase.setValue(Firebase.java:238)
at com.example.appla.iattended.SignUpActivity$5.onClick(SignUpActivity.java:122)
at android.view.View.performClick(View.java:4211)
at android.view.View$PerformClick.run(View.java:17267)
at android.os.Handler.handleCallback(Handler.java:615)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4898)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1006)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773)
at dalvik.system.NativeStart.main(Native Method)
我对此不太确定，因为您正在使用Firebase的遗留版本的错误消息。因此，首先，我建议如果是这样，请查看迁移说明。
firebase的当前版本显示了用于读写和写入数据库的类的预期结构：
@IgnoreExtraProperties
public class User {
public String username;
public String email;
public User() {
// Default constructor required for calls to DataSnapshot.getValue(User.class)
}
public User(String username, String email) {
this.username = username;
this.email = email;
}
}
我不确定这是如何转化为较旧版本的，但是您可能希望尝试包括空构造函数并将您的字段公开。
没有发现的属性... empty_bean
您的字段是包裹私有化的，您没有得到的。
添加一些Getter或将字段公开。
如果您打算使用getValue(User.class)