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Global Variable appending multiple copies of data while updating

I have created a class named "Global Services" which I use to save my data globally and access them in a different activity. But when I am calling the set() method, instead of overview the existing data instead it is appending that data. Below is my code.
I have even tried to remove the instance but still, it is appending the new data instead of overwriting.
import java.util.ArrayList;
import java.util.List;
public class GlobalServices {
private static GlobalServices instance;
String partner, leadsResponse;
List<Leads> assignedList = new ArrayList<>();
List<Leads> unAssignedList = new ArrayList<>();
List<Inventory> listInventory = new ArrayList<>();
private GlobalServices() {}
public static GlobalServices getInstance() {
if (instance == null) {
instance = new GlobalServices();
}
return instance;
}
public static void destory() {
instance = null;
}
public String getPartner() {
return partner;
}
public String getLeadsResponse() {
return leadsResponse;
}
public List<Leads> getAssignedList() {
return assignedList;
}
public List<Leads> getUnAssignedList() {
return unAssignedList;
}
public List<Inventory> getListInventory() {
return listInventory;
}
public void setPartner(String partner) {
this.partner = partner;
}
public void setLeadsResponse(String leadsResponse) {
this.leadsResponse = leadsResponse;
}
public void setAssignedList(List<Leads> assignedList) {
this.assignedList = assignedList;
}
public void setUnAssignedList(List<Leads> unAssignedList) {
this.unAssignedList = unAssignedList;
}
public void setListInventory(List<Inventory> listInventory) {
this.listInventory = listInventory;
}
}

The problem is that you're just assigning new references to your lists in GlobalServices but not creating new lists. This means as soon as you modify this reference from another place in your code, it will be reflected in the GlobalServices list as well. All you have to do is:
public void setAssignedList(List<Leads> assignedList) {
this.assignedList = new ArrayList<>(assignedList);
}
public void setUnAssignedList(List<Leads> unAssignedList) {
this.unAssignedList = new ArrayList<>(unAssignedList);
}
public void setListInventory(List<Inventory> listInventory) {
this.listInventory = new ArrayList<>(listInventory);
}
This way a new copy will be created in memory for each list and the data will be overwritten.

Sorry if I was wrong, but your code here is not a problem.
The problem might come from other part of your application.
The data you set might be the data that extend your current data.
Example you have
GlobalServices instance = GlobalServices.getInstance()
List<Inventory> listInventory1 = new ArrayList<>();
listInventory1.add(new Inventory());
instance.setListInventory(listInventory1); // now your inventory have one item
// In some where else in your project
List<Inventory> listInventory2 = instance.getListInventory(); // lisInventorys.size() equals 1
// Then you add more data to listInventory2 by mistake
listInventory2.add(new Inventory()); // listInventory2.size() equals 2
// Then you set back listInventory2 to your global service
instance.setListInventory(listInventory2); // now your inventory have two item
So, the data had been actually overwrite, it data just been extended by accident.

Multiple values for a single parameter

How to pass multiple values to a single parameter for a particular method in java.
e.g. suppose i have a method with single parameter 'childname', that gets names of all the children in a family.
Now how can i pass multiple values to this parameter to get all different names.
public String getChildrenNames(String childname)
{
children= childname+ familyName;
return children;
}

You would typically implement this using either an Array, or a Collection.
eg:
public String[] getNamesOfChildren()
or
public Collection<String> getNamesOfChildren()

As people say you need to pass them as an Array, so your code should be like this:
String familyName = "Family";
public String[] getChildrenNames(String[] childnames)
{
String[] result = new String[childnames.length];
for(int i=0; i<childnames.length; i++)
{
result[i] = childnames[i] + " " +familyName;
}
return result;
}
public void main()
{
String[] childnames = {"Name1", "Name2", "Name3"};
String[] childnamesAux = getChildrenNames(childnames);
}
With this your childnamesAux variable should have: {"Name1 Family", "Name2 Family", "Name3 Family"}

If you can't change the signature of your method, then you can use concatenation, then in your method you can split this parameter for example :
String childname = firstname + "," + lastname;
getChildrenNames(childname);
so you can split this parametter to get multiple names,
String[] spl = childname.split(",");
But there are better ways then this, if you can change the signature of your method, so you can create a method which can take an array or list of names instead :
public String getChildrenNames(String...childnames) {
or
public String getChildrenNames(Lis<String> childnames) {
You can even create an Object for example :
class Person{
private String firstname;
private String lastname;
//getters and setters
}
Then your method should take an array or a list of Person Object :
public String getChildrenNames(List<Person> childname) {

You can try this
public static String child(String... name){
String[] array=name;
String tem;
if(name.length==1)
return name[0];
for(int counter=0; counter<array.length;counter+=2){
array[0]=name[counter]+name[counter+1];
}
tem=array[0];
return tem;
}
now if you call it
child("Paul","walker");
the output will be
Paul Walker
hope this helped

you can use var args like below
public String getChildrenNames(String... childname)
{
for(String s:childname)
{
children= childname+ s;
}
return children;
}
example
public class Test {
public static void main(String[] args) {
System.out.println(tes("s","d","s"));
}
static String tes(String... x)
{
String y="";
for(String s:x)
{
y=y+s;
}
return y;
}
}
output: sds

ArrayList and connection different classes

Im pretty new to Java. I'm trying to connect these classes together. The Go class, is the main class, that should end up running the program. According to Eclipse, the program doesn't contain any errors, but while running, the outprint is blank.
The Go class:
public class Go {
public static void main(String[] args) {
Data klasseObject = new Data();
klasseObject.infoListe();
}
}
The Ansat class:
import java.util.ArrayList;
public class Ansat {
public String navn;
public int alder;
public Ansat(String navn, int alder, ArrayList<Ansat> ansat){
this.navn = navn;
this.alder = alder;
}
public int getAlder() {
return alder;
}
public void setAlder(int alder) {
this.alder = alder;
}
public String getNavn() {
return navn;
}
public void setNavn(String navn) {
this.navn = navn;
}
}
The Data class:
import java.util.ArrayList;
public class Data {
private ArrayList<Ansat> ansat;
public void infoListe(){
ansat = new ArrayList<Ansat>();
ansat.add(new Ansat("Hej", 123, ansat));
}
public ArrayList<Ansat> getAnsat() {
return ansat;
}
}

Output the contents of ArrayList to console
public class Go {
public static void main(String[] args) {
Data klasseObject = new Data();
klasseObject.infoListe();
for(Ansat ansat : getAnsat()){
system.out.println(ansat.getNavn(), ansat.getAlder());
}
}
}

I recommend just two modifications for you to get a proper readable output.
Add the following method to your Ansat class
//modify the returned string however you want it to appear
public String toString() {
return navn + " , " + alder;
}
and then add this line in your main method of Go class (last statement)
System.out.println(klasseObject.getAnsat().get(0).toString());
The toString() class that is added to the Ansat is overriding the toString() method for Ansat meaning that it allows you to print the fields of Ansat class the way you want it and whenever you invoke toString() on object of Ansat then it will pretty print it for you such as below:
Hej , 123
You can update the toString() method to print it however you want.
If you wish to have more than one element in your ArrayList then you have to do the following changes (but, I do want state that you are not doing this the right way):
Data klasseObject = new Data();
klasseObject.infoListe();
Data klasseObject2 = new Data();
klasseObject.infoListe();
Data klasseObject3 = new Data();
klasseObject.infoListe();
for(Ansat s: klasseObject.getAnsat())
System.out.println(s.toString());
And this changes to your Data class
public void infoListe(){
if(ansat != null) {
ansat.add(new Ansat("Hej", 123, ansat));
} else {
ansat = new ArrayList<Ansat>();
ansat.add(new Ansat("Hej", 123, ansat));
}
}
If I were to review your code and suggest improvements, then I would do the following changes in your classes (copy/paste the following code Go.java file and run it):
import java.util.ArrayList;
public class Go {
public static void main(String[] args) {
// running below creates an ArrayList<Ansat> that is inside KlasseObject
Data klasseObject = new Data();
// creates one Ansat(Hey,123) and add it to list
klasseObject.setData("Hey", 123);
// creates one Ansat(Raf,555) and add it to list
klasseObject.setData("Raf", 555);
// creates one Ansat(X-men,999) and add it to list
klasseObject.setData("X-men", 999);
//as many classes as you want, it would add them all to the list
//of klasseObject
// now that we set three Ansats, we will retrieve the list and print
// them all
for (Ansat s : klasseObject.getAnsatList())
System.out.println(s.toString());
}
}
class Ansat {
public String navn;
public int alder;
//remove the array list from constructor, not needed
public Ansat(String navn, int alder) {
this.navn = navn;
this.alder = alder;
}
public int getAlder() {
return alder;
}
public void setAlder(int alder) {
this.alder = alder;
}
public String getNavn() {
return navn;
}
public void setNavn(String navn) {
this.navn = navn;
}
//overrided toString method to pretty-print Ansat object
public String toString() {
return navn + " , " + alder;
}
}
class Data {
private ArrayList<Ansat> ansat;
// added the constructor for Data to initialize Data with empty list
public Data() {
ansat = new ArrayList<Ansat>();
}
//replaced infoListe to setData and added args to it so you can
//pass them from main method
public void setData(String name, int age) {
// every time setData is called a new Ansat is added to list
Ansat a = new Ansat(name, age);
ansat.add(a);
}
public ArrayList<Ansat> getAnsatList() {
return ansat;
}
}

Actually the process what you have followed is perfectly correct,But your getting blank because your not printing the arraylist, hence your getting blank output. Just add the below line and you will see the correct output.
public void infoListe(){
ansat = new ArrayList<Ansat>();
ansat.add(new Ansat("Hej", 123, ansat));
System.out.println(ansat);
}
or in the main function just use it like this...
public static void main(String[] args) {
Data klasseObject = new Data();
klasseObject.infoListe();
System.out.println(klasseObject.getAnsat());
}
Even iterating over array list will fetch you the output -
for (Ansat ansatLoop : klasseObject.getAnsat()) {
System.out.println(ansatLoop.getAlder() + ":"
+ ansatLoop.getNavn());
}
I hope this would solve your query.

Your code is working Perfectly! It has no
System.out.println();
anywhere in the methods that run.
If you modify the method infoListe() to add a println it will print something out
public void infoListe(){
ansat = new ArrayList<Ansat>();
ansat.add(new Ansat("Hej", 123, ansat));
System.out.println("Element Added to ArrayList");
}

How to Store objects in an ArrayList when you do not know how many object you need to create?

Back ground: I am pairing up two pieces of data, both Strings, into an ArrayList. Therefore I am storing the paired data into an object, and then storing this object into an ArrayList. I have a text file that for each word, I am assigning a number to. The paired data is then word-number (but I have typed them both as String). I do not know how many objects I will need for any given file size.
How do I set up a logic to iterate through the text file and populate my ArrayList. This is what I have done so far:
The : PredictivePrototype.wordToSignature(aWord)// converts the word into a number signature e.g "4663" for a word like "home"
public class ListDictionary {
private static ArrayList<WordSig> dictionary;
public ListDictionary() throws FileNotFoundException {
File theFile = new File("words");
Scanner src = new Scanner(theFile);
while (src.hasNext()) {
String aWord = src.next();
String sigOfWord = PredictivePrototype.wordToSignature(aWord);
// assign each word and its corresponding signature into attribute
// of an object(p) of class WordSig.
//WordSig p1 = new WordSig(aWord, sigOfWord);
//Then add this instance (object) of class Wordsig into ArrayList<WordSig>
dictionary.add(new WordSig(aWord, sigOfWord));
}
src.close();
}
Other class to which paired data is stored:
public class WordSig {
private String words;
private String signature;
public WordSig(String words, String signature) {
this.words=words;
this.signature=signature;
}
}

Your code seems to be OK. With ArrayList you can add as many elements as you want (by using add() function).
Here is an example:
import java.util.ArrayList;
public class ListDictionary {
public class WordSig {
private String words;
private String signature;
public WordSig(String words, String signature) {
this.words=words;
this.signature=signature;
}
public String getWords() {
return words;
}
public String getSignature() {
return signature;
}
}
private static ArrayList<WordSig> dictionary = new ArrayList<WordSig>();
public ListDictionary() {
// add as many as you want
for ( int i=0; i < 10; i++)
dictionary.add(new WordSig("key"+i, "value"+i));
}
public static class testListDictionary {
public static void main(String[] args) {
new ListDictionary();
// test output
for ( int i=0; i < dictionary.size(); i++ )
System.out.println( "<" + dictionary.get(i).getWords() + "|"
+ dictionary.get(i).getSignature() + ">");
}
}
}

separate the string and number from list in android

i want to split the mProductType is one list and mRetailerid is another list.how can i get it ????
public class RetailerNames implements Serializable{
private String mProductType;
private String mRetailerid;
public String getmProductType() {
return mProductType;
}
public void setmProductType(String mProductType) {
this.mProductType = mProductType;
}
public String getmRetailerid() {
return mRetailerid;
}
public void setmRetailerid(String mRetailerid) {
this.mRetailerid = mRetailerid;
}
#Override
public String toString() {
return mProductType + "," +
mRetailerid ;
}
I have used below code :
ArrayList<RetailerNames> retailerNamesList = (ArrayList<RetailerNames>) getIntent().getExtras().getSerializable("ProductsDetailsDescriptionPage");
System.out.println("The retailer details are"+" "+retailerNamesList);
Now my current output is:
The retailer details are [Krish,48, Danesh,47]
But i want to get the one list like [Krish,Danesh] .and [48,47] is separate another list.How can i do ???
please give me solution ???
please give me a ideas to split the array list to separate list???

ArrayList list = new ArrayList();
Iterator<RetailerNames > retaileriterator = retailerNamesList.iterator();
while(retaileriterator.hasNext()){
id=retaileriterator .next().getmRetailerid();
System.out.println(id);
list.add(id);
}
System.out.println(list);

In my condition getLocationDetails return arraylist
and LocationDetails is POJO same like your class RetailerNames
Iterator<LocationDetails> it= getUserLocationsWrapper.getLocationDetails().iterator();
while(locationCitiDetailsItr.hasNext()){
locationCitiDetailsItr.next().getCity());
}
same i think try this one
Iterator<RetailerNames > retaileriterator = retailerNamesList.iterator();
while(retaileriterator.hasNext()){
Object id=retaileriterator .next().getmRetailerid();
//add this id into another list
//same RetailerNames
}

use nested array
Put [Krish,48] is one list and
[damesh,47] in another list and put both the list in one main array list

Use like this
public class RetailerNames implements Serializable{
private String mProductType;
private String mRetailerid;
public String getmProductType() {
return mProductType;
}
public void setmProductType(String mProductType) {
this.mProductType = mProductType;
}
public String getmRetailerid() {
return mRetailerid;
}
public void setmRetailerid(String mRetailerid) {
this.mRetailerid = mRetailerid;
}
#Override
public String toString() {
return + mProductType + ","
+ mRetailerid +; //Remove "[" this..
}
And,
ArrayList<RetailerNames> retailerNamesList = (ArrayList<RetailerNames>) getIntent().getExtras().getSerializable("ProductsDetailsDescriptionPage");
System.out.println("The retailer details are"+" "+retailerNamesList);
Now try
Object temp[]=retailerNamesList.toArray();
String[] values=temp.toString().split(",");
String names=values[0];
String names=values[1];