convert String to Custom ArrayList

Question

I have a custom Array List need to save in sqlite ,i converted this array list into string using to string method and saved it in database. Now i need again this Array list.So how can i convert custom Array List form this particular String.

Here's the code i used to convert Array to String

ArrayList<Publication> pb = new Array List<Publication>();
pb.add(new Publication("", ""));
String st = pb.tostring();

Now I added st in SQLite database as a string. My problem is how I revert back to custom ArrayList of publication from this string.

How did you saved the Array List? Adding comma (,) after each string? — Karun Shrestha
– Karun Shrestha, Commented Jan 20, 2017 at 8:52
Array List<Publication> pb=new Array List<Publication>(); pb.add(new Publication("","")); String st=pb.tostring(); Now i added "st" in sqlite database as a string.My problem is how i revert back to custom arraylist of publication from this string. — Rims
– Rims, Commented Jan 20, 2017 at 8:55

Mayur Gangurde · Accepted Answer · 2017-01-20 09:04:24Z

2

You can use Gson Library to convert string to Custom ArrayList. Add this gradle dependency in your app build.gradle

compile 'com.google.code.gson:gson:2.2.+'

then use this code

Gson gson = new Gson();
TypeToken<ArrayList<Publication>> token = new TypeToken<ArrayList<Publication>>() {
    };
ArrayList<Publication> pb = gson.fromJson(str, token.getType());

answered Jan 20, 2017 at 9:04

Mayur Gangurde

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5 Comments

Rims Over a year ago

I am getting string value from sqlite database like this [common.Publication@8301fc7, common.Publication@11659f4] and your code is not working here.Here common is my package name and Publication is a class name.

Mayur Gangurde Over a year ago

What are the parameters of Publication class constructor?

Rims Over a year ago

there are multiple fields, like int publication_id; byte[] publication_image; String publication_date; String publication_color

Mayur Gangurde Over a year ago

@ReemaSing Don't convert Custom arraylist to string like using toString method. You should use the Gson library to convert custom arraylist to string like String str = new Gson().toJson(pb); And then put this String str into the database.

Rims Over a year ago

Thanx.finally its done.whatever i want. Thanx a lot.:)

Athul · Accepted Answer · 2017-01-20 09:38:34Z

0

If seperated by ","

String[] strValues = str.split(",");//this is the string u saved in sqlite

/*Use asList method of Arrays class to convert Java String array to ArrayList*/
ArrayList<Publication> aList = new ArrayList<Publication>();
for(i=0; i<strValues.count(); i++)
aList.add(new Publication().setField(strValues[i]));

Now the custom Class Publication

class Publication{
String field;

public void setField(String f) {

field=f;
}

public String getField() {

return field;
}

}

or

for (String value: strValues) {
   aList.add(new Publication(value));
}

class Publication {
   private final String input;

   public Publication(String input) {
      this.input = input;
   }

   // not needed but implemented for completeness    
   public static Publication parse(String input) {
      return new Publication(input);
   }
}

Check this: You wont be able to insert ArrayList directly into Sqlite. Instead, you could use JSONObject (org.json.JSONObject) to insert the ArrayList. Please check below and give it a shot....

//Add values to arraylist item
ArrayList<Publication> item = new ArrayList<Publication>();
item.add  //add the item to array list

To insert,

JSONObject json = new JSONObject();
json.put("uniqueArrays", new JSONArray(items));
String arrayList = json.toString();
Insert the string into db.

To Read, Read the string from db as String,

JSONObject json = new JSONObject(stringreadfromsqlite);
  ArrayList<Publication> items = json.optJSONArray("uniqueArrays");

edited Jan 20, 2017 at 9:38

answered Jan 20, 2017 at 8:55

Athul

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14 Comments

Rims Over a year ago

I am using ArrayList<Publication> ,it means custom object.

Athul Over a year ago

Wt are fields in Publication then

Athul Over a year ago

@Rheema are there multiple fields in publication

Rims Over a year ago

yes,there are multiple fields, like int publication_id; byte[] publication_image; String publication_date; String publication_color;

Athul Over a year ago

@ReemaSingh Are u getting wt i'am trying to describe

|

Quick learner · Accepted Answer · 2018-10-09 06:27:43Z

0

  Updates to Mayur Gangurde's Answer for Kotlin:-

Import the gson using this in your app gradle:-

compile 'com.google.code.gson:gson:2.2.+'

Then in your kotlin class Declare custom arraylist object variable

var publicationListing = ArrayList< Publication>()

Then Convert String to custom arraylist like this

val gson = Gson();
val token = object : TypeToken<ArrayList< Publication>>() {}
publicationListing = gson.fromJson(str, token.getType())

answered Oct 9, 2018 at 6:27

Quick learner

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