Develop Reference

Can't convert object of type java.lang.Boolean Android Studio

I don't have any boolean value in my firebase database but on fetching the data from database to the recycler view it shows Can't convert object of type java.lang.Boolean this type of error,and application crashes after crash if i open the application it starts but again if any value is added in the database the app crashes again
My code
Query query = FirebaseDatabase.getInstance().getReference().child("Users").child("Donor");
model = new FirebaseRecyclerOptions.Builder<ShowDonorDetails>().setQuery(query,ShowDonorDetails.class).build();
adapter = new FirebaseRecyclerAdapter<ShowDonorDetails, ShowDonorDetailsAdapter>(model) {
#Override
protected void onBindViewHolder(#NonNull ShowDonorDetailsAdapter holder, int position, #NonNull ShowDonorDetails model) {
holder.t1.setText(model.getFname());
holder.t2.setText(model.getLname());
holder.t3.setText(model.getBloodgroup());
}
#NonNull
#Override
public ShowDonorDetailsAdapter onCreateViewHolder(#NonNull ViewGroup viewGroup, int i) {
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.showdonordetails,viewGroup,false);
return new ShowDonorDetailsAdapter(view);
}
};
Model class:
public class ShowDonorDetails {
String fname,lname,phone,status,enddate,bloodgroup,age,address;
public String getFname() {
return fname;
}
public void setFname(String fname) {
this.fname = fname;
}
public String getLname() {
return lname;
}
public void setLname(String lname) {
this.lname = lname;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public String getStatus() {
return status;
}
public void setStatus(String status) {
this.status = status;
}
public String getEnddate() {
return enddate;
}
public void setEnddate(String enddate) {
this.enddate = enddate;
}
public String getBloodgroup() {
return bloodgroup;
}
public void setBloodgroup(String bloodgroup) {
this.bloodgroup = bloodgroup;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public ShowDonorDetails(String fname, String lname, String phone, String status, String enddate, String bloodgroup, String age, String address) {
this.fname = fname;
this.lname = lname;
this.phone = phone;
this.status = status;
this.enddate = enddate;
this.bloodgroup = bloodgroup;
this.age = age;
this.address = address;
}
public ShowDonorDetails() {
}
my Logcat:
my Database :
can anyone please help me?

You're telling FirebaseUI that the child nodes of Donor are all ShowDonorDetails objects, and it looks like at least one child node under Donor is instead a single boolean value. You'll need to ensure each child node is a ShowDonorDetails object to make this work.

Create list with unique id in Java and manipulate it

I want to create a programm that creates a list that looks like this
ID: 1
Name: Example
Surname: Example
email: example
//New list
ID: 2
Name: Example
Surname: Example
email: example
and then when i want to change something (like Name: ) i'd like to change it by id, so it can only be changed inside the list with ID: 2

You should use a HashMap.
Create a class (let's class it YourClass) that contains ID, name, surname and email instance variables.
Then create a HashMap where the key is the identifier and the value is YourClass:
Map<Integer,YourClass> map = new HashMap<>();
map.put(objectOfYourClassWithID1.getID(),objectOfYourClassWithID1);
map.put(objectOfYourClassWithID2.getID(),objectOfYourClassWithID2);
if (map.containsKey(2)) {
map.get(2).setSomeProperty(newValue); // this will only change the object whose ID is 2
}

you can create class like this
public class Record{
private int id;
private String name;
private String Surname;
private String email;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSurname() {
return Surname;
}
public void setSurname(String surname) {
Surname = surname;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
}
and then use it like this:
Record record1 = new Record();
record1.setId(1);
record1.setName("example");
record1.setSurname("example");
record1.setEmail("example");
Record record2 = new Record();
record2.setId(2);
record2.setName("example");
record2.setSurname("example");
record2.setEmail("example");
Map<Integer,Record> recordMap = new HashMap<Integer, Record>();
recordMap.put(record1.getId(),record1);
recordMap.put(record2.getId(),record2);]
recordMap.get(2).getName();//example
recordMap.get(2).setName("ebi");
recordMap.get(2).getName();//ebi

import java.util.ArrayList;
import java.util.List;
public class Person {
private int id;
private String name;
private String Surname;
private String email;
public Person(int id, String name, String surname, String email) {
super();
this.id = id;
this.name = name;
Surname = surname;
this.email = email;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSurname() {
return Surname;
}
public void setSurname(String surname) {
Surname = surname;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public static void main(String[] args) {
List<Person> list = new ArrayList<Person>();
list.add(new Person(1, "example", "example", "example"));
list.add(new Person(2, "example", "example", "example"));
}
}

Validating response from REST API call

I am working on error handling a response mapping. Before I go ahead and map the response to my domain objects, I want to validate the response. Check for errors.
I am planning to have a Validator.java class and implement validation methods for each of the API call.
Is there any alternative way in spring to do this?

package com.people.net;
import javax.validation.constraints.Pattern;
import javax.validation.constraints.Size;
import org.hibernate.validator.constraints.Email;
public class UserInfo {
//Unicode check
#Pattern(regexp="[0-9a-zA-Z\\s-]+", message="chars,numbers allowed only")
String name;
int id;
#Pattern(regexp="([0-9]{10})", message="minLength=maxLength=10 only numbers")
String pin;
#Email
String email;
#Size(max=5, message="5 chars max")
String emailType;
#Size(max=5, message="5 chars max")
String addressType;
#Size(max=300, message="5 chars max")
String address;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public UserInfo(String name, String pin, String id) {
super();
this.id = Integer.parseInt(id);
this.name = name;
this.pin = pin;
}
public UserInfo(int id,String name, String pin, String email, String emailType, String addressType, String address) {
super();
this.id = id;
this.name = name;
this.pin = pin;
this.email = email;
this.emailType = emailType;
this.addressType = addressType;
this.address = address;
}
public UserInfo() {
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getPin() {
return pin;
}
public void setPin(String pin) {
this.pin = pin;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getEmailType() {
return emailType;
}
public void setEmailType(String emailType) {
this.emailType = emailType;
}
public String getAddressType() {
return addressType;
}
public void setAddressType(String addressType) {
this.addressType = addressType;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}

You should explore hibernate validator which is the reference implementation JSR-349 for bean validation. more info is here https://jcp.org/en/jsr/detail?id=349 .
Also hibernate validator is a industry standard for doing the bean validation(lots of stuff available on internet) and comes with lots of popular framework like dropwizard etc.it provide annotation based validation and allow you to write your own custom annotation based validation.
please refer on step by step guide http://www.journaldev.com/2668/spring-validation-example-mvc-validator, where author uses it with the spring.

It show the error that Customer is already defined.Please let me know whats wrong and how to correct it

There is a compliation error stating that class name is already define i can't find the way to resolve it
further the class name are declared only once and can't find the place where the things are going wrong
package practo;
import java.io.*;
import java.lang.*;
import java.util.*;
#SuppressWarnings("unused")
class Customer /* compilation error occurs here */
{
private int id;
private String name;
private String email;
private String address;
void setid(int id)
{
this.id=id;
}
int getid()
{
return id;
}
void setname(String name)
{
this.name=name;
}
String getname()
{
return name;
}
void setemail(String email)
{
this.email=email;
}
String getemail()
{
return email;
}
void setaddress(String address)
{
this.address=address;
}
String getaddress()
{
return address;
}
class PhoneNumber
{
private String phoneNumber;
private String heldFromDate;
private String heldToDate;
void setphoneNumber(String phoneNumber)
{
this.phoneNumber=phoneNumber;
}
String getphoneNumber()
{
return phoneNumber;
}
void setheldToDate(String heldToDate)
{
this.heldToDate=heldToDate;
}
String getheldToDate()
{
return heldToDate;
}
public String getHeldFromDate() {
return heldFromDate;
}
public void setHeldFromDate(String heldFromDate) {
this.heldFromDate = heldFromDate;
}
class NumberType
{
private String code;
private String description;
void setcode(String code)
{
this.code=code;
}
void setdescription(String description)
{
this.description=description;
}
String getcode()
{
return code;
}
String getdescription()
{
return description;
}
}
}
}
class x1
{
public void main(String args[])
{
#SuppressWarnings("resource")
Scanner s=new Scanner(System.in);
Customer c=new Customer();
Customer.PhoneNumber p=c.new PhoneNumber();
Customer.PhoneNumber.NumberType n=p.new NumberType();
System.out.println("Enter the customer details");
System.out.println("Enter the id :");
int id=s.nextInt();
c.setid(id);
System.out.println(c.getid());
System.out.println("Enter the name :");
String name=s.nextLine();
c.setname(name);
System.out.println(c.getname());
System.out.println("Enter the email :");
String email=s.nextLine();
c.setemail(email);
System.out.println(c.getemail());
System.out.println("Enter the address :");
String address=s.nextLine();
c.setaddress(address);
System.out.println(c.getaddress());
System.out.println("Enter the customer contact details");
System.out.println("Enter the phone number :");
String phoneNumber=s.nextLine();
p.setphoneNumber(phoneNumber);
System.out.println(p.getphoneNumber());
System.out.println("Enter the held from date (dd/MM/yyyy) :");
String heldFromDate=s.next();
p.setHeldFromDate(heldFromDate);
System.out.println(p.getHeldFromDate());
System.out.println("Enter the held to date (dd/MM/yyyy) :");
String heldToDate=s.next();
p.setheldToDate(heldToDate);
System.out.println(p.getheldToDate());
System.out.println("Enter number type code :");
String code=s.next();
n.setcode(code);
System.out.println(n.getcode());
System.out.println("Enter number type description");
String description=s.next();
n.setdescription(description);
System.out.println(n.getdescription());
}
}

Your class does not give me any compilation error. You might try making the class public i.e. public class Customer and file name having the name Customer.java. It may happen that the package practo already contains a class named Customer.

Can you please verify Customer class is not duplicate ? If it is not there, can you choose Clean from the Project menu, it might fix these errors.
Sometime eclipse trouble us.

Lots of recommendations for improvement:
Open public class per file, and a file for each class. Your arrangement is confusing.
Learn and follow the Java coding standards.
Using a Date for a date instead of a String is a better design, especially with JDK 8 and the java.time package.
Learn JUnit instead of that x1.main.
These are examples of how your classes should look.
Customer.java
package practo;
/**
* Created by Michael
* Creation date 5/29/2016.
* #link https://stackoverflow.com/questions/37511168/it-show-the-error-that-customer-is-already-defined-please-let-me-know-whats-wron
*/
public class Customer {
private int id;
private String name;
private String email;
private String address;
public Customer() {
this(0, "", "", "");
}
public Customer(int id, String name, String email, String address) {
this.id = id;
this.name = name;
this.email = email;
this.address = address;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
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 getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}
PhoneNumber.java:
package practo;
/**
* Created by Michael
* Creation date 5/29/2016.
* #link https://stackoverflow.com/questions/37511168/it-show-the-error-that-customer-is-already-defined-please-let-me-know-whats-wron
*/
public class PhoneNumber {
private String phoneNumber;
private String heldFromDate; // Bad design. This ought to be a Date, not a String
private String heldToDate; // Bad design. This ought to be a Date, not a String
public PhoneNumber() {
this("", "", "");
}
public PhoneNumber(String phoneNumber, String heldFromDate, String heldToDate) {
this.phoneNumber = phoneNumber;
this.heldFromDate = heldFromDate;
this.heldToDate = heldToDate;
}
public String getPhoneNumber() {
return phoneNumber;
}
public void setPhoneNumber(String phoneNumber) {
this.phoneNumber = phoneNumber;
}
public String getHeldFromDate() {
return heldFromDate;
}
public void setHeldFromDate(String heldFromDate) {
this.heldFromDate = heldFromDate;
}
public String getHeldToDate() {
return heldToDate;
}
public void setHeldToDate(String heldToDate) {
this.heldToDate = heldToDate;
}
}

Check if you have another class called Customer in the package practo. That would cause a name conflict.

deleting lines from a file

I need to delete certain lines from a file, the file is a list of contacts that I read in from a file into my GUI. When I get to the contact I want to delete, my program should delete the contact from the file. I've tried to do this, but it is not working.
Here is the code I'm currently using:
String temp=txtname.getText();
for (Contact Contact:contacts)
{
if (temp.equals(Contact.getname()));
{
txtname.setText("");
txtsurname.setText("");
txtphone.setText("");
txtmobile.setText("");
txtaddress.setText("");
txtpostcode.setText("");
contacts.remove(Contact);
contacts.remove(Contact);
contacts.remove(Contact);
contacts.remove(Contact);
contacts.remove(Contact);
contacts.remove(Contact);
}
}
My contact class is:
public class Contact {
static void add(String text) {
}
public String name;
public String surname;
public String phone;
public String mobile;
public String address;
public String postcode;
public Contact(){}
public Contact(String name, String surname, String phone,
String mobile, String address, String postcode)
{
this.name = name;
this.surname = surname;
this.phone = phone;
this.mobile = mobile;
this.address = address;
this.postcode = postcode;
}
public String getname()
{
return this.name;
}
public String getsurname()
{
return this.surname;
}
public String getphone()
{
return this.phone;
}
public String getmobile()
{
return this.mobile;
}
public String getaddress()
{
return this.address;
}
public String getpostcode()
{
return this.postcode;
}
public void setname(String name)
{
this.name = name;
}
public void setsurname(String surname)
{
this.surname = surname;
}
public void setphone(String phone)
{
this.phone = phone;
}
public void setmobile(String mobile)
{
this.mobile = mobile;
}
public void setaddress(String address)
{
this.address = address;
}
public void setpostcode(String postcode)
{
this.postcode = postcode;
}
}
I'm guessing it deletes it from the arraylist, but I'm not sure how the program knows what to delete from the file.
Thanks.

Modifying the internal list doesn't change the file. There is no automatic way to synchronize the two. You have to save the array back to the file to update it.

There is no way to delete anything from the middle of the file.
The only way is to rewrite the file every time something should be changed.

you can use a random access file but it seems like an over kill for this task.
the best way to do it is to have the remove function write the whole file back to the disk.

If you have no specific format for the file, then I suggest you to use the default serialization and serialize the contacts list. Like this,
//To serialize
ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(new File("D:/newfile.txt")));
out.writeObject(contacts);
//To deserialize
ObjectInputStream in = new ObjectInputStream(new FileInputStream(new File("d:/newFile.txt")));
contacts = (ArrayList<Contact>)in.readObject();
You first have to implement the Serializable interface in your Contact class.
Or if you need more control over the file format use the standard XML classes or JSON libraries.

Files can be rewrited, or appended to. In you case you'll have to rewrite it. There are other ways, but they would be an overkill here.
String temp = txtname.getText();
for (Contact contact : contacts) {
if (temp.equals(contact.getname())) {
contacts.remove(contact);
break;
}
}
Fixed a lot of general problems with your code
public class Contact {
private String name;
private String surname;
private String phone;
private String mobile;
private String address;
private String postcode;
public Contact(String name, String surname, String phone, String mobile, String address, String postcode) {
this.name = name;
this.surname = surname;
this.phone = phone;
this.mobile = mobile;
this.address = address;
this.postcode = postcode;
}
public String getName() {
return this.name;
}
public String getSurname() {
return this.surname;
}
public String getPhone() {
return this.phone;
}
public String getMobile() {
return this.mobile;
}
public String getAddress() {
return this.address;
}
public String getPostcode() {
return this.postcode;
}
}