FireBase Database Exception while uploading values

Got these errors in Run logcat: E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.shikh.regie, PID: 19366 com.google.firebase.database.DatabaseException: Failed to parse node with class class com.example.shikh.regie.User at com.google.android.gms.internal.zzamm.zza(Unknown Source) at com.google.android.gms.internal.zzamm.zzbt(Unknown Source) at com.google.android.gms.internal.zzamp.zzbu(Unknown Source) at com.google.firebase.database.DatabaseReference.setValue(Unknown Source) at com.example.shikh.regie.MainActivity$1.onClick(MainActivity.java:40)

Dont know whats the problem.why it is not able to parse the node

MainActivity.java

public class MainActivity extends AppCompatActivity {
private EditText name,email,phone;
private Button btn;
private DatabaseReference mDatabse;
private String name1,email1,phone1;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mDatabse = FirebaseDatabase.getInstance().getReference().child("AppUsers");

    name = (EditText) findViewById(R.id.editText);
    email = (EditText) findViewById(R.id.editText2);
    phone = (EditText) findViewById(R.id.editText3);

    name1 = name.getText().toString();
    email1 = email.getText().toString();
    phone1 = phone.getText().toString();
    btn = (Button) findViewById(R.id.button);
         btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Map<String, User> users = new HashMap<String, User>();
            DatabaseReference ref=mDatabse.child("AppUsers");
            mDatabse.setValue(email1,new User(name1,email1,phone1));
            mDatabse.setValue(users);
        }
    });

}
}

User.java

package com.example.shikh.regie;


public class User {
String name,email,phone;

public User(){}

public User(String name, String email, String phone) {
    this.name = name;
    this.email = email;
    this.phone = phone;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getEmail() {
    return email;
}

public void setEmail(String email) {
    this.email = email;
}

public String getPhone() {
    return phone;
}

public void setPhone(String phone) {
    this.phone = phone;
}
 }