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Android Array list returns Null after adding values


Android Array list returns Null after adding values

By : mmcmac
Date : December 01 2020, 05:00 PM
fixed the issue. Will look into that further I am trying to add values to array list for ploting xAxis value in mpandroid chart but while debugging array list returns Null , create AsynchTask task that will return arraylist like
code :
public class DemoAsynch extends AsyncTask<Context, Integer, ArrayList<String>>{

}
ArrayList<String> abc = new DemoAsynch().execute().get();


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Android: Sax parsing returns null values and retrieve values in tags of same name

Android: Sax parsing returns null values and retrieve values in tags of same name


By : user3021227
Date : March 29 2020, 07:55 AM
should help you out This code makes the incorrect assumption that the characters method will be called only once between the startElement and endElement calls for a tag.
Instead of having the logic for setting the values in the characters method, you need initialize a buffer in the startElement method, collect characters into the buffer in the characters method, and then make the assignments and clear the buffer in the endElement method.
code :
<?xml version="1.0" encoding="ISO-8859-1" ?>
<PhoneBook>
    <PhoneBookEntry>
        <FirstName>John</FirstName>
        <LastName>Connor</LastName>
        <Address>5,Downing Street</Address>
        <Phone loc="home">9875674567</Phone>
        <Phone loc="work">9875674567</Phone>
        <Phone loc="mobile">78654562341</Phone>
    </PhoneBookEntry>
    <PhoneBookEntry>
        <FirstName>John</FirstName>
        <LastName>Smith</LastName>
        <Address>6,Downing Street</Address>
        <Phone loc="home">678-56-home</Phone>
        <Phone loc="work">678-59-work</Phone>
        <Phone loc="mobile">678-85-mobile</Phone>
    </PhoneBookEntry>
</PhoneBook>
public class ParsedExampleDataSet {
    private String firstName = null;
    private String lastName =null;
    private String address =null;
    private String homePhone =null;
    private String workPhone =null;
    private String mobilePhone =null;


    //Firstname
    public String getFirstName() {
         return firstName;
    }
    public void setFirstName(String firstName) {
         this.firstName = firstName;
    }

    //Lastname
    public String getLastName(){
        return lastName;
    }
    public void setLastName(String lastName){
        this.lastName = lastName;
    }

    //address
    public String getAddress(){
        return address;
    }
    public void setAddress(String Address){
        this.address =Address;
    }

    public void setHomePhone(String homePhone){
        this.homePhone =homePhone;
    }
    public void setWorkPhone(String homePhone){
        this.workPhone =homePhone;
    }
    public void setMobilePhone(String homePhone){
        this.mobilePhone =homePhone;
    }


    public String toString(){
         return "firstName: " + this.firstName + "\n" + "lastName=: " + this.lastName + "\n" + "address: " + this.address + "\n"  + "homePhone: " + this.homePhone + "\n" + "workPhone: " + this.workPhone + "\n" + "mobilePhone: " + this.mobilePhone;

    }
}
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

import java.util.ArrayList;
import java.util.List;

public class ExampleHandler extends DefaultHandler {

    // ===========================================================
    // Fields
    // ===========================================================

    private boolean in_homePhone = false;
    private boolean in_workPhone = false;
    private boolean in_mobilePhone = false;

    private StringBuffer stringBuffer;

    private List<ParsedExampleDataSet> myParsedExampleDataSets;
    private ParsedExampleDataSet myParsedExampleDataSet;

    // ===========================================================
    // Methods
    // ===========================================================

    public List<ParsedExampleDataSet> getParsedData() {
        return myParsedExampleDataSets;
    }

    @Override
    public void startDocument() throws SAXException {
        myParsedExampleDataSets = new ArrayList<ParsedExampleDataSet>();
        stringBuffer = new StringBuffer();
    }

    @Override
    public void endDocument() throws SAXException {
        // Nothing to do
    }

    /**
     * Gets be called on opening tags like:
     * <tag>
     * Can provide attribute(s), when xml was like:
     * <tag attribute="attributeValue">
     */
    @Override
    public void startElement(String namespaceURI, String localName,
                             String qName, Attributes atts) throws SAXException {

        if (qName.equals("PhoneBookEntry")) {
            myParsedExampleDataSet = new ParsedExampleDataSet();
        }

        if (qName.equals("Phone")) {
            String phoneLocation = atts.getValue("loc");
            if (phoneLocation.equals("home")) {
                this.in_homePhone = true;
            } else if (phoneLocation.equals("work")) {
                this.in_workPhone = true;
            } else if (phoneLocation.equals("mobile")) {
                this.in_mobilePhone = true;
            }
        }
    }

    /**
     * Gets be called on closing tags like:
     * </tag>
     */
    @Override
    public void endElement(String namespaceURI, String localName, String qName)
            throws SAXException {

        String result = stringBuffer.toString();
        stringBuffer.setLength(0);

        if (in_homePhone) {
            myParsedExampleDataSet.setHomePhone(result);
            in_homePhone = false;
        }
        else if (in_mobilePhone) {
            myParsedExampleDataSet.setMobilePhone(result);
            in_mobilePhone = false;
        }
        else if (in_workPhone) {
            myParsedExampleDataSet.setWorkPhone(result);
            in_workPhone = false;
        }
        else if (qName.equals("FirstName")) {
            myParsedExampleDataSet.setFirstName(result);
        }
        else if (qName.equals("LastName")) {
            myParsedExampleDataSet.setLastName(result);
        }
        else if (qName.equals("Address")) {
            myParsedExampleDataSet.setAddress(result);
        }
        else if (qName.equals("PhoneBookEntry")) {
            myParsedExampleDataSets.add(myParsedExampleDataSet);
        }
    }

    /**
     * Gets be called on the following structure:
     * <tag>characters</tag>
     */
    @Override
    public void characters(char ch[], int start, int length) {
        stringBuffer.append(new String(ch, start, length));
    }

}
Hibernate returns list with null values (OneToMany annotation with List type)

Hibernate returns list with null values (OneToMany annotation with List type)


By : matmurray
Date : March 29 2020, 07:55 AM
To fix the issue you can do I am experiencing a problem where as Hibernate (4.1.8.FINAL) returns a list with NULL values (unidirectional OneToMany mapping). , I found the solution, I used it and this solved the issue
code :
@OneToMany(orphanRemoval = true)
@LazyCollection(LazyCollectionOption.FALSE)
@JoinColumn(name = "entry_id")
@OrderBy("precedence")
private List<EntryAddress> addresses;

@OneToMany(orphanRemoval = true)
@LazyCollection(LazyCollectionOption.FALSE)
@JoinColumn(name = "entry_id")
@OrderBy("precedence")
private List<EntryContact> contacts;
Android - Volley with GSON returns null list of values

Android - Volley with GSON returns null list of values


By : Legend Protocol
Date : March 29 2020, 07:55 AM
wish helps you EDIT: to @njzk2 I was able to correct this, the problem lies in the objArray class, the variable holding the array is called "results", there is no element or array in the JSON file called results, that's what made the value null, my array in the JSON file was called "tag", thus the variable should have been named "tag".
code :
public ArrayList<Tag> tag;
return Response.success(gson.fromJson(new JSONObject(json).getString("tag"),clazz),HttpHeaderParser.parseCacheHeaders(response));
public class obj {
    private String id;
    private String name;
   public obj(){}
    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }
    public void setId(String id) {
        this.id = id;
    }

    public void setName(String name) {
        this.name= name;
    }
}
Recursively adding to list returns null

Recursively adding to list returns null


By : John Cizmar
Date : March 29 2020, 07:55 AM
should help you out Your code fails because you forgot the else part in the cond expression, also the way you're appending a single element to the end of a list is incorrect. This should fix the problems:
code :
(define (add-end set)
  (cond ((null? set)
         '())
        (else
         (cons (append (first set) (list (first (first set))))
               (add-end (rest set))))))
(define (add-end set)
  (map (lambda (lst)
         (append lst (list (first lst))))
       set))
(add-end '((0 0 1) (1 0 0) (0 1 0)))
=> '((0 0 1 0) (1 0 0 1) (0 1 0 0))
Firebase/Android: Adding retrieved values from Firebase to arraylist returns null pointer exception

Firebase/Android: Adding retrieved values from Firebase to arraylist returns null pointer exception


By : Jcdavo
Date : March 29 2020, 07:55 AM
To fix this issue It's hard to be certain from the code you shared, by I suspect you may be bitten by the fact that all data is loaded from Firebase asynchronously. Alternatively you may simply not have permission to read the data. I'll give an answer for both.
Data is loaded asynchronously
code :
System.out.println("Before attaching listener");
q.addChildEventListener(new ChildEventListener() {
    public void onChildAdded(DataSnapshot dataSnapshot, String s) {
        System.out.println("In onChildAdded");    
    }
    public void onChildChanged(DataSnapshot dataSnapshot, String s) { }
    public void onChildRemoved(DataSnapshot dataSnapshot) { }
    public void onChildMoved(DataSnapshot dataSnapshot, String s) { }
    public void onCancelled(DatabaseError databaseError) { }
});
System.out.println("After attaching listener");
q.addChildEventListener(new ChildEventListener() {
    public void onChildAdded(DataSnapshot dataSnapshot, String s) {
        allBrands.add((dataSnapshot.getValue(Brand.class)).getBrandName());  
        System.out.println(allBrands.length); 
    }
public void onCancelled(DatabaseError databaseError) {
    throw databaseError.toException();
}
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