There are 2 fragments: A and B. From fragment A i want to send ArrayList (data) to fragment B.

action() - a method in which data transfer and transition to fragment B should occur (using navigate()). The program builds without errors, but when you click on the button to which the action method is attached, a crash occurs, the error is as follows:

java.lang.IllegalArgumentException: Wrong argument type for 'array' in argument bundle. java.util.ArrayList expected.

It says that I inserted an argument of the wrong type into the Bundle, an ArrayList is needed. But it is an ArrayList, isn't it?

Please help, i've been struggling with this problem for 2 days now. My code is below.

Fragment A code:

package com.github.dev.app.pack;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import androidx.navigation.fragment.NavHostFragment;
import com.github.vladosspasi.mes.databinding.FragmentABinding;
import java.util.ArrayList;

public class FragmentA extends Fragment {

    private FragmentABinding binding;
    private ArrayList<Integer> data; // ArrayList that i want to send
    @Override
    public View onCreateView(
            LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState
    ) {
        binding = FragmentAsBinding.inflate(inflater, container, false);
        return binding.getRoot();
    }


    public void onViewCreated(@NonNull View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        data = new ArrayList<>(); 
        data.add(1);              

        binding.actionButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                action();   //method with navigating to fragmentB and data transmitting
            }
        });
    }

    @Override
    public void onDestroyView() {
        super.onDestroyView();
        binding = null;
    }

    private void action() {

        Bundle arg = new Bundle();
        arg.putSerializable("array", data); //putIntegerArrayList doesn't work either

        NavHostFragment.findNavController(FragmentA.this)
             .navigate(R.id.action_FragmentA_to_FragmentB, arg); //exception ocuring here

    }
}

Fragments declaration in nav_graph.xml:

    <fragment
            android:id="@ id/FragmentA"
            android:name="com.github.dev.app.pack.FragmentA"
            android:label="Fragment A">
        <action
            android:id="@ id/action_FragmentA_to_FragmentB"
            app:destination="@id/FragmentB"/>
    </fragment>

    <fragment
            android:id="@ id/FragmentB"
            android:name="com.github.dev.app.pack.FragmentB"
            android:label="Fragment B">
        <argument android:name="array" app:argType="java.util.ArrayList"/>
    </fragment>

int, String and other arguments are working properly, but ArrayList isn't. Please help! Thank you.

CodePudding user response：

Please use below code to send the data from one fragment to another fragment

 Bundle bundle = new Bundle();
 bundle.putParcelableArrayList("array",data);