Passing a List from one Activity to another

Question

How to pass Collections like ArrayList, etc from one Activity to another as we used to pass Strings, int with help of putExtra method of Intent?

Can anyone please help me as i want to pass a List<String> from one Activity to another?

Winebaum

Please do a search before posting; stackoverflow.com/… – Supersaturated

Please See this Blog. This Can Help You – Costume

Answer 1

You can pass an ArrayList<E> the same way, if the E type is Serializable.

You would call the putExtra (String name, Serializable value) of Intent to store, and getSerializableExtra (String name) for retrieval.

Example:

ArrayList<String> myList = new ArrayList<String>();
intent.putExtra("mylist", myList);

In the other Activity:

ArrayList<String> myList = (ArrayList<String>) getIntent().getSerializableExtra("mylist");

---

Please note that serialization can cause performance issues: it takes time, and a lot of objects will be allocated (and thus, have to be garbage collected).

Isabel

One thing worth mentioning is, List interface does not extend Serializable so if your collection is declared by interface you have to cast it to a specific implementation first. – Rakel

Answer 2

First you need to create a Parcelable object class, see the example

public class Student implements Parcelable {

        int id;
        String name;

        public Student(int id, String name) {
            this.id = id;
            this.name = name;

        }

        public int getId() {
            return id;
        }

        public String getName() {
            return name;
        }


        @Override
        public int describeContents() {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public void writeToParcel(Parcel dest, int arg1) {
            // TODO Auto-generated method stub
            dest.writeInt(id);
            dest.writeString(name);
        }

        public Student(Parcel in) {
            id = in.readInt();
            name = in.readString();
        }

        public static final Parcelable.Creator<Student> CREATOR = new Parcelable.Creator<Student>() {
            public Student createFromParcel(Parcel in) {
                return new Student(in);
            }

            public Student[] newArray(int size) {
                return new Student[size];
            }
        };
    }

And the list

ArrayList<Student> arraylist = new ArrayList<Student>();

Code from Calling activity

Intent intent = new Intent(this, SecondActivity.class);
Bundle bundle = new Bundle();
bundle.putParcelableArrayList("mylist", arraylist);
intent.putExtras(bundle);       
this.startActivity(intent);

Code on called activity

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_second);   

    Bundle bundle = getIntent().getExtras();
    ArrayList<Student> arraylist = bundle.getParcelableArrayList("mylist");
}

Obeisance

Working like a charm, after an hour i got this, many thanks buddy. – Biome

Its better to use serializable then this one, But Its good for someone. +1 – Megrims

@HarishReddy Could you explain why using serializable is better? I thought Parcelable is better than serializable for the performance. – Tension

As it works on order basis as values are given in writeToParcel. Is there any mechanism to get values from Parcel object on key basis?. For example if in class we have multiple string fields then how can we come to know which string we are getting from Parcel in Student(Parcel in) . – Thurmond

@HarishReddy: Using Serializable allows for a simpler implementation, but using Parcelable provides better performance. Which one is better depends on the circumstances: if the performance Serializable provides in your use case is adequate, then you should prefer the simpler approach. But if using Serializable is too slow in your use case, you should try using Parcelable instead. – Mazuma

@Shahin ShamS Could you please have a look at this question. I tried to implement your solution there: #68051180 – Andesite

Answer 3

use putExtra to pass value to an intent. use getSerializableExtra method to retrieve the data like this

Activity A :

ArrayList<String> list = new ArrayList<String>();

intent.putExtra("arraylist", list);
startActivity(intent);

Activity B:

ArrayList<String> list = getIntent().getSerializableExtra("arraylist");

Narghile

Hi RajaReddy, I pass array list A activity to B activity. B activity i have changed one value and come back to A activity value not changing. Please help me – Prospector

While coming back to B Activity you have to pass data From B to A.. or make that array as global array and update from B activity . – Narghile

In my case i have option to go C activity. In that scenario how can i update the arraylist? – Prospector

Then make it as Global in Application class... and update and use where ever you want to use – Narghile

Thanks for your tips. If possible give me ur mail id, I will ask doubts through email. – Prospector

Answer 4

I tried all the proposed techniques but none of them worked and stopped my app from working and then I finally succedded. Here is how I did it... In main activity I did this:

            List<String> myList...;
            Intent intent = new Intent...;
            Bundle b=new Bundle();
            b.putStringArrayList("KEY",(ArrayList<String>)myList);            
            intent_deviceList.putExtras(b);
            ....startActivity(intent);

To get the data in the new Activity:

    List<String> myList...
    Bundle b = getIntent().getExtras();
    if (b != null) {
        myList = bundle.getStringArrayList("KEY");
    }

I hope this will help someone...

Guyette

Answer 5

To pass ArrayList from one activity to another activity, one should include

intent.putStringArrayListExtra(KEY, list); //where list is ArrayList which you want to pass

before starting the activity.And to get the ArrayList in another activity include

Bundle bundle = getIntent().getExtras();
        if (bundle != null) {
            temp = bundle.getStringArrayList(KEY); // declare temp as ArrayList
                }

you will be able to pass ArrayList through this.Hope this will be helpful to you.

Coloring

Answer 6

Use of ViewModel is better fix than Serializable or Parcelable

Commoner

You cannot pass ViewModel between activities. – Arabian