How to transfer data between two fragment with RecyclerView Adapter?-CodePudding

I tried to transfer data from View Fragment which contains RecycleView to Display Fragment... but I'm getting null Exception Error every time while using bundle

Here is my code.

Inside Adapter

 public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        StringIntString ping=arrayList.get(position);
        holder.name.setText(ping.getmString());
        holder.desc.setText(ping.getnString());
        holder.num.setText(Integer.toString(ping.getmInt()));
        holder.layout.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                Bundle bundle=new Bundle();
                bundle.putString("name", ping.getmString());
                bundle.putString("desc", ping.getnString());
                bundle.putString("num",Integer.toString(ping.getmInt()));
                DisplayFrag frag=new DisplayFrag();
                frag.setArguments(bundle);

                
                ((FragmentActivity)view.getContext()).getSupportFragmentManager().beginTransaction().setCustomAnimations(R.anim.fade_in,R.anim.slide_out).replace(R.id.fragview,DisplayFrag.class,null).commit();
            }
        });

    }

Inside Display view

 @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        v=inflater.inflate(R.layout.fragment_viewfrag2, container, false);
        name=v.findViewById(R.id.box1);
        desc=v.findViewById(R.id.box2);
        num=v.findViewById(R.id.box3);
        Bundle bundle=this.getArguments();
      // if(bundle != null) {
           name.setText(bundle.getString("name"));
           desc.setText(bundle.getString("desc"));
           num.setText(bundle.getInt("num"));
      // }
        return v;
    }

Log Message

E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.myapplication, PID: 31856 java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference at com.example.myapplication.DisplayFrag.onCreateView(DisplayFrag.java:31) at androidx.fragment.app.Fragment.performCreateView(Fragment.java:3104) at androidx.fragment.app.FragmentStateManager.createView(FragmentStateManager.java:524) at androidx.fragment.app.FragmentStateManager.moveToExpectedState(FragmentStateManager.java:261) at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:1899) at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:1817) at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1760) at androidx.fragment.app.FragmentManager$5.run(FragmentManager.java:547) at android.os.Handler.handleCallback(Handler.java:938) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loopOnce(Looper.java:201) at android.os.Looper.loop(Looper.java:288) at android.app.ActivityThread.main(ActivityThread.java:7839) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003)

I'm expecting to transfer data from View fragment to Display fragmnet

CodePudding user response：

The error "java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference" occurs because the bundle is null. To resolve the issue, you should check if the bundle is null before accessing its values, like this:

Bundle bundle = this.getArguments();
if (bundle != null) {
   name.setText(bundle.getString("name"));
   desc.setText(bundle.getString("desc"));
   num.setText(Integer.toString(bundle.getInt("num")));
}

And in the adapter, change this line num.setText(Integer.toString(ping.getmInt())); to num.putString("num", Integer.toString(ping.getmInt()));.

CodePudding user response：

In your RecyclerView adapter define a new variable like below

MutableLiveData<String> nameMutableLiveDataString = new MutableLiveData<>();
MutableLiveData<String> descMutableLiveDataString = new MutableLiveData<>();
MutableLiveData<Integer> numMutableLiveDataString = new MutableLiveData<>();

and your onBindViewHolder will look something like this

public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        StringIntString ping=arrayList.get(position);
        holder.name.setText(ping.getmString());
        holder.desc.setText(ping.getnString());
        holder.num.setText(Integer.toString(ping.getmInt()));
        holder.layout.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                nameMutableLiveDataString.postValue(ping.getmString());
                descMutableLiveDataString.postValue(ping.getnString());
                numMutableLiveDataString.postValue(ping.getmInt());
                // Bundle bundle=new Bundle();
                // bundle.putString("name", ping.getmString());
                // bundle.putString("desc", ping.getnString());
                // bundle.putString("num",Integer.toString(ping.getmInt()));
                DisplayFrag frag=new DisplayFrag();
                // frag.setArguments(bundle);


                ((FragmentActivity)view.getContext()).getSupportFragmentManager().beginTransaction().setCustomAnimations(R.anim.fade_in,R.anim.slide_out).replace(R.id.fragview,DisplayFrag.class,null).commit();
            }
        });

    }

and your view class something like this

@Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        v=inflater.inflate(R.layout.fragment_viewfrag2, container, false);
        name=v.findViewById(R.id.box1);
        desc=v.findViewById(R.id.box2);
        num=v.findViewById(R.id.box3);
        Bundle bundle=this.getArguments();
        // if(bundle != null) {

        recyclerviewAdapter. nameMutableLiveDataString.observe((LifecycleOwner) this, new Observer<String>()
        {
            @Override
            public void onChanged(String s)
            {
                name.setText(s);
            }
        });

        recyclerviewAdapter.descMutableLiveDataString.observe((LifecycleOwner) this, new Observer<String>()
        {
            @Override
            public void onChanged(String s)
            {
                desc.setText(s);
            }
        });

        recyclerviewAdapter.;
        numMutableLiveDataString.observe((LifecycleOwner) this, new Observer<Integer>()
        {
            @Override
            public void onChanged(Integer s)
            {
                num.setText(s.toString());
            }
        });


        // }
        return v;
    }