Develop Reference

All my firebase field get automatically an underscore on front

My PoIs class:
public class PoIs {
private Integer location_id;
private String location_name;
private String location_address;
public PoIs() {}
public PoIs(Integer location_id, String location_name, String location_address) {
this();
this.location_id = location_id;
this.category_id = category_id;
this.location_name = location_name;
this.location_address = location_address;
}
public Integer get_location_id() {
return location_id;
}
public void set_location_id(Integer location_id) {
this.location_id = location_id;
}
public String get_location_name() {
return location_name;
}
public void set_location_name(String location_name) {
this.location_name = location_name;
}
public String get_location_address() {
return location_address;
}
public void set_location_address(String location_address) {
this.location_address = location_address;
}
I populate PoIs with informatision from a sqlite database:
final PoIs p = new PoIs(Integer.parseInt(row.get(0).toString()), row.get(1).toString(), row.get(2).toString());
and at a moment intend to save them on a firabase database:
FIREBASE_REFERENCE.child("PoI_"+ p.get_location_id()).setValue(p)
.addOnCompleteListener(t -> {
final boolean isSuccessful = t.isSuccessful();
final String msg = !isSuccessful
? getResources().getString(R.string.fb_error)
: getResources().getString(R.string.fb_success);
});
All work perfect except that my firebase fields start with an underscore. Instead location_id, location_name, location_address I have _location_id, _location_name, _location_address. I can't understand why this happening. Any ideea how to resolve this issue?

Firebase uses JavaBean naming conventions when mapping from properties in your code to properties in the database. In that convention a method like get_location_name is the getter for a property called _location_name.
If you want the property in the database to be location_name, that'd be a getter getLocation_name. Alternatively, you can use a #PropertyName("location_name")) annotation on all accessors (so the getter/setter function and/or the public field) to indicate the explicit property name you want in the database.

Using a class without creating a new instance of it

Newish to Java and very new to Android development.
I have followed the following tutorial - Android tutorial (Basic Hello World App) and I am now changing it slightly as a proof of concept.
Basically I want to use a class I have created but I am having some difficulties. The class is shown below.
public class Employee {
private HashMap<String, String> employees = new HashMap<>();
public void setEmployees(String name, String jobTitle) {
employees.put(name, jobTitle);
System.out.println(employees);
}
public String getEmployees(String name){
return employees.get(name);
}
}
I populate the HashMap from MainActivity.java. Using the set method above, this works as expected. I have tested it and I can see the HashMap has the required number of entries.
My problem is when getting the data back. How do I use the class. I have a file name DisplayMessageActivity.java and the following code within it.
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;
public class DisplayMessageActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_display_message);
// Get the Intent that started this activity and extract the string
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
// Capture the layout's TextView and set the string as its text
TextView employee_name = findViewById(R.id.employee_Name);
employee_name.setText(message);
TextView employee_title = findViewById(R.id.employee_Title);
employee_title.setText(employee.getEmployees(message));
}
}
The last line is where I am getting the error. This is because it doesnt know what employee is. I presume I need to add:
Employee employee = new Employee;
If I add this within the onCreate method it creates a new instance and therefore it has new values. I have also added it just above onCreate with the same results.
What am I missing?

To retain the data you would want to make the variable and the methods static
public class Employee {
private static HashMap<String, String> employees = new HashMap<>();
public static void setEmployees(String name, String jobTitle) {
employees.put(name, jobTitle);
System.out.println(employees);
}
public static String getEmployees(String name){
return employees.get(name);
}
}
This means that only one version can exist at a time. You would call the class directly and the method.
employee_title.setText(Employee.getEmployees(message))

Replace your Employee class code with below one
public class Employee {
private static HashMap<String, String> employees;
public Employee() {
if (employees == null) {
employees = new HashMap<>();
}
}
public void setEmployees(String name, String jobTitle) {
employees.put(name, jobTitle);
System.out.println(employees);
}
public String getEmployees(String name) {
return employees.get(name);
}
}
Hope that helps you.

You can use Singleton in-memory cache to keep your employees.
public class Employee {
private static sInstance;
private HashMap<String, String> employees = new HashMap<>();
private Employee(){
// No instance available
}
public static synchronized Employee getInstance(){
if(sInstance == null){
sInstance = new Employee();
}
return sInstance;
}
public void setEmployees(String name, String jobTitle) {
employees.put(name, jobTitle);
System.out.println(employees);
}
public String getEmployees(String name){
return employees.get(name);
}
}
Later you can use your in-memory cache like the following:
Employee.getInstance().getEmployees(message);

Pass Provider as extra of Intent

I have a provider that takes a decent number of properties. For example:
public MyProvider(
byte[] image,
String firstName,
String nickName,
String lastName,
String hairColor,
String favoriteFood,
String favoriteColor,
String cityBorn,
String stateBorn,
long favoriteNumber,
int age,
String nameOfFather,
String nameOfMother,
String nameOfBestFriend
)
I do know that I can get the value of each property, and set each individual one as an extra, like so:
Intent myIntent = new Intent(firstActivity.this, secondActivity.class);
myIntent.putExtra("firstName", myProvider.getFirstName().toString());
myIntent.putExtra("nickName", myProvider.getNickName().toString());
...
firstActivity.this.startActivity(myIntent);
I would like to just pass the entire provider as an extra, and then be able to get the provider in the next activity. I know it's possible to do such a thing in Swift, but I am not sure how to do so in Java for Android Studio.
What I am hoping to be able to do is something like the following:
MyProvider newPerson = new MyProvider(image, firstName, nickName, lastName, hairColor, favoriteFood, favoriteColor, cityBorn, stateBorn, favoriteNumber, age, nameOfFather, nameOfMother, nameOfBestFriend);
intent.putExtra(newPerson);
But it seems like a provider cannot be passed like this (or possibly at all?).
Alternative Attempt:
I also attempted passing it as data like a URI (see here), but .setData is specifically for URIs.
Is there such a way to pass the entire provider as an extra, and then be able to get the provider in the next activity?
Thanks in advance.
EDIT
I have implemented Parcelable as #NabinBhandari and #JuanCruzSoler suggested, but it is causing the following error:
Cannot resolve constructor 'MyProvider(byte[], java.lang.String, long)'
when I call:
MyApartmentsProvider newApartment = new MyApartmentsProvider(image, firstName, favoriteNumber);
My updated MyProvider.java is as follows:
(note: I cut out some variables for the time being to make the example easier to work with)
import android.os.Parcel;
import android.os.Parcelable;
public class MyProvider implements Parcelable {
/////////////////////////
// Initializers
byte[] image;
String firstName;
long favoriteNumber;
// End of [Initializers]
/////////////////////////
/////////////////////////
// Getters
public byte[] getImage() {
return image;
}
public String getFirstName() {
return firstName;
}
public long getFavoriteNumber() {
return favoriteNumber;
}
// End of [Getters]
/////////////////////////
/////////////////////////
// Setters
public void setImage(byte[] image) {
this.image = image;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public void setFavoriteNumber(long favoriteNumber) {
this.favoriteNumber = favoriteNumber;
}
// End of [Setters]
/////////////////////////
public MyProvider() {
super();
}
public MyProvider(Parcel parcel) {
image = new byte[parcel.readInt()];
parcel.readByteArray(image);
this.firstName = parcel.readString();
this.favoriteNumber = parcel.readLong();
}
#Override
public int describeContents() {
return 0;
}
#Override
public void writeToParcel(Parcel parcel, int i) {
parcel.writeInt(image.length);
parcel.writeByteArray(image);
parcel.writeString(this.firstName);
parcel.writeLong(this.favoriteNumber);
}
public static final Creator<MyProvider> CREATOR=new Creator<MyProvider>() {
#Override
public MyProvider createFromParcel(Parcel parcel) {
return new MyProvider(parcel);
}
#Override
public MyProvider[] newArray(int i) {
return new MyProvider[i];
}
};
}

Make your Provider class implement the interface Serializable or Parcelable.
Parcelable is faster but Serializable is easier to implement.
To send:
intent.putExtra(KEY, yourObj);
To receive:
Provider provider = (Provider) getIntent().getSerializableExtra(KEY);

Hibernate One-To-Many Mapping, printing mapped lists

I have used One-to-Many Mapping in my project. I have stored a list of clicks for every user.
But when I retrieve the list by calling getClicks() methodm Hibernate returns list in different format.
Something like this.
"[com.zednx.tech.persistence.Click#29df9a77]"
So I tried Reading Every value from the list and assign to a new List.
List<Click> clicks=new ArrayList<Click>();
for(Click c: e.getClicks()){
Click temp = new Click();
temp.setAff_source(c.getAff_source());
temp.setCb_to_award(c.getCb_to_award());
temp.setCb_type(c.getCb_type());
clicks.add(temp);
}
But when i print the items of new List it stills prints the same way.
I need to build a JSON from the resulting String of this list.
So if the list is returned in format, it wont help me.
I couldn't find anything regarding this except How to pretty print Hibernate query results?
I tried Arrays.ToString(Object o). But it doesn't work.
GSON builder part-
Gson gson = new GsonBuilder()
.registerTypeAdapter(Click.class, new MyTypeAdapter<Click>())
.create();
List<Click> clicks=new ArrayList<Click>();
for(Click c: e.getClicks()){
Click temp = new Click();
temp.setAff_source(c.getAff_source());
temp.setCb_to_award(c.getCb_to_award());
temp.setCb_type(c.getCb_type());
temp.setCom_to_recieve(c.getCom_to_recieve());
temp.setStore_name(c.getStore_name());
temp.setT_date(c.getT_date());
temp.setT_status(c.getT_status());
temp.setT_ticket(c.getT_ticket());
temp.setUid(c.getUid());
System.out.println(c.toString());
clicks.add(temp);
}
String json = gson.toJson(clicks, Click.class);
Click.java
#Entity
#Table(name="click")
public class Click {
#Id
#Column(name="t_ticket")
private String t_ticket;
#Column(name="uid",nullable=false)
private long uid;
public long getUid() {
return uid;
}
public void setUid(long uid) {
this.uid = uid;
}
#ManyToOne
#JoinColumn(name="uid",
insertable=false, updatable=false,
nullable=false)
private Earning earning;
#Column(name="store_name")
private String store_name;
#Column(name="t_status")
private String t_status;
#Column(name="aff_source")
private String aff_source;
#Column(name="com_to_recieve")
private float com_to_recieve;
#Column(name="t_date")
private Date t_date;
#Column(name="cb_to_award")
private float cb_to_award;
#Column(name="cb_type")
private String cb_type;
public String getT_ticket() {
return t_ticket;
}
public void setT_ticket(String t_ticket) {
this.t_ticket = t_ticket;
}
public Earning getEarning() {
return earning;
}
public void setEarning(Earning earning) {
this.earning = earning;
}
public String getStore_name() {
return store_name;
}
public void setStore_name(String store_name) {
this.store_name = store_name;
}
public String getT_status() {
return t_status;
}
public void setT_status(String t_status) {
this.t_status = t_status;
}
public String getAff_source() {
return aff_source;
}
public void setAff_source(String aff_source) {
this.aff_source = aff_source;
}
public float getCom_to_recieve() {
return com_to_recieve;
}
public void setCom_to_recieve(float com_to_recieve) {
this.com_to_recieve = com_to_recieve;
}
public Date getT_date() {
return t_date;
}
public void setT_date(Date t_date) {
this.t_date = t_date;
}
public float getCb_to_award() {
return cb_to_award;
}
public void setCb_to_award(float cb_to_award) {
this.cb_to_award = cb_to_award;
}
public String getCb_type() {
return cb_type;
}
public void setCb_type(String cb_type) {
this.cb_type = cb_type;
}
Any Help is appreciated.

You need to implement a toString method, as your current Click class likely doesn't have one, so it just prints as the name of the class and instance identifier.

Okay, I could solve my problem finally.
I made another POJO without any annotations and Mapped the List items to that POJO class.
I think the problem was with Annotation of mapping on another class which I had in original POJO.
Also getString() method only helps in changing format of identifier. So basically it has nothing to do with JSON building unless you format getString() in form of JSON.
Hope it helps. If anyone wants new temp POJO I made I can post it if requested.
Thanks.

How to Insert ArrayList data to the DataBase

Im try to insert data into Database using ArrayList.there is a Erro msg.
That is my Custmer.class method. this is what i got from when i going to pass ArrayList into another class.
incompatible types: ArrayList<String> cannot be converted to ArrayList<Inquiries>
I want to know how to do this using correct Using OOP concept
public void passingMsg(ArrayList<Inquiries> arrlist){
try {
System.out.println("Method "+arrlist);
String sq = "INSERT INTO Inquiries (name,mail,tp,msg)VALUES(?,?,?)";
PreparedStatement pr = con.prepareStatement(sq);
for(int i=0;i<arrlist.size();i++){
pr.setString(1,arrlist.get(i).getName());
pr.setString(2,arrlist.get(i).getMail());
pr.setString(3,arrlist.get(i).getTp());
pr.setString(4,arrlist.get(i).getMsg());
}
pr.executeQuery();//executeBatch();
} catch (SQLException ex) {
}
}
and this is how i get values from user
String name = txtName.getText();
String mail = txtEmail.getText();
String tp = txtTp.getText();
String msg = txtMsg.getText();
ArrayList<String> arrInq = new ArrayList<String>();
arrInq.add(name);
arrInq.add(mail);
arrInq.add(tp);
arrInq.add(msg);
Custmer c =new Custmer();
if( c.passingMsg(arrInq)){
try {
JOptionPane.showMessageDialog(this, "Successs!!");
} catch (Exception e) {
JOptionPane.showMessageDialog(this, "Unsuccesss!!");
e.printStackTrace();
}
}
and this is my Inquiries.class :
public class Inquiries {
private String name;
private String mail;
private String tp;
private String msg;
public Inquiries(String name,String mail,String tp,String msg){
this.name = name;
this.mail = mail;
this.tp = tp;
this.msg = msg;
}
//
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getMail() {
return mail;
}
public void setMail(String mail) {
this.mail = mail;
}
public String getTp() {
return tp;
}
public void setTp(String tp) {
this.tp = tp;
}
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
}
Can Some one please explain whats wrong with this. please ?

Reason For Error
This was simply telling you that your types were incompatible for the operation you were trying to perform. In your passingMsg() method, you have its header as: public void passingMsg(ArrayList<Inquiries> arrlist). However, inside your "how i get values from user" area, which I will now refer to as "2nd Snippet", you have your method call declared as: if( c.passingMsg(arrInq)). This means that you are implying that your parameter being passed, arrInq in this case, is of the type ArrayList<Inquiries>, but it's not. It's being initialized in your 2nd Snippet as: ArrayList<String> arrInq = new ArrayList<String>();
Simple Fix
I take no responsibility for this code; use at your own risk. To fix this, you would want to change that entire 2nd Snippet to something similar to the following:
String name = txtName.getText();
String mail = txtEmail.getText();
String tp = txtTp.getText();
String msg = txtMsg.getText();
ArrayList<Inquiries> arrInq = new ArrayList<Inquiries>();
arrInq.add(new Inquiries(name, mail, tp, msg));
Custmer c = new Custmer();
try {
c.passingMsg(arrInq);
JOptionPane.showMessageDialog(this, "Successs!!");
} catch (Exception e) {
JOptionPane.showMessageDialog(this, "Unsuccesss!!");
e.printStackTrace();
}
You would also want to change the method header to either return a boolean, or fix it up a little bit to actually throw the exception. Such as:
public void passingMsg(ArrayList<Inquiries> arrlist) {
System.out.println("Method " + arrlist);
String sq = "INSERT INTO Inquiries(name,mail,tp,msg) VALUES(?,?,?)";
PreparedStatement pr = con.prepareStatement(sq);
for (Inquiries inquiries : arrlist) {
pr.setString(1, inquiries.getName());
pr.setString(2, inquiries.getMail());
pr.setString(3, inquiries.getTp());
pr.setString(4, inquiries.getMsg());
}
pr.executeQuery();//executeBatch();
}

Let's talk in O-O-P way.
Here Inquiries is your model, model is nothing but simple class that has instance members and public methods to get and set value of model's instance variable.
Generally we put all database related operations code in their respective models.
e.g. I have model "Model" which typically maps to database table say it as "TableModel" ,I would do something like this:
public class Model{
private int id;
private String attr;
//other properties of the model
public int getId(){
return id;
}
public void setId(int id){
this.id=id;
}
//other getters and setters
//here we write methods to performs database operations
public void save(){
//use "this" to get properties of object
//logic to save to this object in database table TableModel as record
}
public void delete(int id){
//logic to delete this object i.e. from database table TableModel
}
public Model get(int id){
//retrieve record from table TableModel with this id
}
//other methods to get data from database.
}
Now question is how I can use this in some another class. Let's say I have list of Model objects and I wish to insert them in to database.I will do it something like this:
public class AnotherClass{
public void someMethod(){
//create list of models objects e.g. get them from user interface
ArrayList<Model> models=new ArrayList<>();
for(int i=0;i<3;i++){
Model model=new Model();
model.setId(i);
model.setAttr("attr"+i);
models.add(model);
}
SomeOtherClass obj=new SomeOtherClass();
obj.insert(models);
}
}
public class SomeOtherClass{
//other code above.....
//my method that inserts each Model object in database
//Note: this is sample method , you should do it in optimized way
// e.g. batch insert
public void insert(ArrayList<Model> models){
for(Model myModel:models){
myModel.save();
}
}
//other code below.....
}

You are using the wrong type parameter for the ArrayList. Instead of ArrayList<String> you need ArrayList<Inquiries>. To fix the problem, you should remove this code ...
ArrayList<String> arrInq = new ArrayList<String>();
arrInq.add(name);
arrInq.add(mail);
arrInq.add(tp);
arrInq.add(msg);
... and replace it with this code:
ArrayList<Inquiries> arrInq = new ArrayList<Inquiries>();
arrInq.add(new Inquiries(name, mail, tp, msg));