如何从Activity1的RecyclerView适配器向Activity2的ViewPager碎片传递数据？

Got it, let's work through this properly. The core mistake here is trying to set arguments for a Fragment belonging to Activity2 directly from Activity1's adapter—Activity2 hasn't been launched yet, so that approach won't work. The right flow is: send data from the adapter to Activity2 first, then pass that data from Activity2 to its ViewPager's Fragment.

Here's the step-by-step solution:

Step 1: Pass Data from RecyclerView Adapter to Activity2 via Intent #

In your adapter's onBindViewHolder click listener, use an Intent to send the required data to Activity2 instead of trying to create and configure the Fragment directly:

@Override 
public void onBindViewHolder(ViewHolder holder, final int position) { 
    holder.itemView.setOnClickListener(new View.OnClickListener() { 
        @Override 
        public void onClick(View view) { 
            // Grab the data you need to pass
            String projectName = jobCardLists.get(position).getProject();
            
            // Create intent to launch Activity2
            Intent intent = new Intent(view.getContext(), Activity2.class);
            // Add the data to the intent (use a unique key for the extra)
            intent.putExtra("EXTRA_PROJECT_NAME", projectName);
            // Start Activity2
            view.getContext().startActivity(intent);
        } 
    });
}

Step 2: Receive Data in Activity2 and Pass It to the ViewPager Fragment #

First, Activity2 needs to catch the data sent from Activity1. Then, when setting up the ViewPager's adapter, pass that data to the target Fragment using setArguments().

2.1 Receive Data in Activity2 #

public class Activity2 extends AppCompatActivity {
    private String mReceivedProjectName;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_2);
        
        // Fetch the data from the incoming intent
        if (getIntent() != null && getIntent().hasExtra("EXTRA_PROJECT_NAME")) {
            mReceivedProjectName = getIntent().getStringExtra("EXTRA_PROJECT_NAME");
        }
        
        // Initialize ViewPager and its adapter
        ViewPager viewPager = findViewById(R.id.your_view_pager_id);
        viewPager.setAdapter(new ViewPagerAdapter(getSupportFragmentManager()));
    }
}

2.2 Create ViewPager Adapter to Pass Data to Fragment #

Use a custom FragmentPagerAdapter (or FragmentStatePagerAdapter for larger datasets) to create your Fragment instance and attach the arguments:

private class ViewPagerAdapter extends FragmentPagerAdapter {
    public ViewPagerAdapter(FragmentManager fm) {
        super(fm, FragmentPagerAdapter.BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT);
    }

    @Override
    public Fragment getItem(int position) {
        // Initialize your DetailsFragment
        DetailsFragment detailsFragment = new DetailsFragment();
        
        // Create a Bundle to hold the data
        Bundle args = new Bundle();
        args.putString("projectName", mReceivedProjectName);
        
        // Attach the bundle to the Fragment
        detailsFragment.setArguments(args);
        
        return detailsFragment;
    }

    @Override
    public int getCount() {
        // Return the number of pages in your ViewPager (adjust as needed)
        return 1;
    }
}

Step 3: Retrieve the Data in DetailsFragment #

Finally, pull the data from the Fragment's arguments in its lifecycle methods (like onCreate or onViewCreated):

public class DetailsFragment extends Fragment {
    private String mProjectName;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // Get the data from arguments
        if (getArguments() != null) {
            mProjectName = getArguments().getString("projectName");
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_details, container, false);
        
        // Use the data to update your UI (example with a TextView)
        TextView projectNameTv = view.findViewById(R.id.tv_project_name);
        if (mProjectName != null) {
            projectNameTv.setText(mProjectName);
        }
        
        return view;
    }
}

Key Notes to Remember #

• Don't create Activity2's Fragment in Activity1's adapter: The Fragment is tied to Activity2's lifecycle, which hasn't started yet—this will cause unexpected behavior.
• Use Intents for Activity-to-Activity communication: This is the standard Android pattern for passing data between activities.
• For complex objects: If you need to pass something other than a String, make sure the object implements Parcelable or Serializable, then use intent.putExtra("EXTRA_OBJECT", yourParcelableObject) to send it.

内容的提问来源于stack exchange，提问作者Adarsh Vijayan P