我无法将对象添加到Firebase实时数据库。我尝试了以下代码。但是当此代码执行userRef.child（“ Users”）。child（Integer.toString（random.nextInt（100）））。setValue（newUser）; 我的应用程序崩溃了。
public class MainActivity extends AppCompatActivity {
private FirebaseAuth mAuth;
private DatabaseReference userRef;
EditText nameEditText;
EditText passEditText;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
nameEditText = (EditText) findViewById(R.id.nameEditText);
passEditText = (EditText) findViewById(R.id.passEditText);
mAuth = FirebaseAuth.getInstance();
// signInAnonymously();
mAuth.signInAnonymously().addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
}
public void onFailure(Throwable throwable) {
throw new RuntimeException(throwable);
}
});
}
public void createUser(View view){
Random random = new Random();
userRef = FirebaseDatabase.getInstance().getReference();
String userN = String.valueOf(nameEditText.getText());
String pass = String.valueOf(passEditText.getText());
UserDetails newUser = new UserDetails(userN,pass);
userRef.child("Users").child(Integer.toString(random.nextInt(100))).setValue(newUser);
}
@IgnoreExtraProperties
public class UserDetails{
public String userName;
public String password;
public UserDetails(){
}
public UserDetails(String userName, String userPass){
this.userName = userName;
this.password = userPass;
Log.i("Check", this.userName);
}
public String getUserName() {
return userName;
}
public String getPassword() {
return password;
}
}
}
这是logcat错误消息。
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.crossappfactory.username, PID: 20144
java.lang.IllegalStateException: Could not execute method for android:onClick
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
at android.view.View.performClick(View.java:4785)
at android.view.View$PerformClick.run(View.java:19884)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5343)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:905)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:700)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
at android.view.View.performClick(View.java:4785)
at android.view.View$PerformClick.run(View.java:19884)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5343)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:905)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:700)
Caused by: com.google.firebase.database.DatabaseException: Invalid key: this$0. Keys must not contain '/', '.', '#', '$', '[', or ']'
at com.google.android.gms.internal.zzaiw.zziv(Unknown Source)
at com.google.android.gms.internal.zzaiw.zzau(Unknown Source)
at com.google.firebase.database.DatabaseReference.zza(Unknown Source)
at com.google.firebase.database.DatabaseReference.setValue(Unknown Source)
at com.crossappfactory.username.MainActivity.createUser(MainActivity.java:63)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
at android.view.View.performClick(View.java:4785)
at android.view.View$PerformClick.run(View.java:19884)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5343)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:905)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:700)
解决方案很简单，将UserDetails类标记为静态，因此编译器不会生成额外的字段：
public static class UserDetails {
如果您有兴趣，请解释为什么需要这样做。
错误消息指出了问题所在，但在这种情况下很难解析：“无效的密钥：this $ 0。密钥不得包含'/'、'.'、'#'、'$'，'['或']'“
它说this$0，这是对您的UserDetails对象的引用。该$0指出，其一个内部类的MainActivity。当您创建内部类时，该类的实例将获得一个额外的隐藏字段，该隐藏字段引用其包含的对象，以便您可以this.MainActivity在的代码中进行说UserDetails。但是Firebase SDK无法处理此额外的隐藏字段，因此会引发异常。
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