android:- How to change the language of list items of recyclerview?

I am new to android.I want to change the language of my list items of recyclerview. My list items are stored in string array in values.How can i change the language of list items on the click of list item. Here is the code it tried but i got error.Can someone please correct my error or show me the right way to achieve the desired result.

error:-

java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
                  at com.example.chaitanya.kundli.MainActivity.setLocale(MainActivity.java:60)
                  at com.example.chaitanya.kundli.RecyclerViewAdapter$1.onClick(RecyclerViewAdapter.java:66)
                  at android.view.View.performClick(View.java:4759)
                  at android.view.View$PerformClick.run(View.java:19770)
                  at android.os.Handler.handleCallback(Handler.java:739)
                  at android.os.Handler.dispatchMessage(Handler.java:95)
                  at android.os.Looper.loop(Looper.java:135)
                  at android.app.ActivityThread.main(ActivityThread.java:5237)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at java.lang.reflect.Method.invoke(Method.java:372)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:912)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:707)

MainActivity.java

 public class MainActivity extends AppCompatActivity {
android.content.res.Resources res;

RecyclerView recyclerView;

Context context;
String[] numbers;

RecyclerView.Adapter recyclerView_Adapter;

RecyclerView.LayoutManager recyclerViewLayoutManager;


@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);
    res = getResources();

    numbers = res.getStringArray(R.array.abc);
    getSupportActionBar().setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);
    getSupportActionBar().setCustomView(R.layout.action_bar);

    context = getApplicationContext();

    recyclerView = (RecyclerView) findViewById(R.id.recycler_view1);

    //Change 2 to your choice because here 2 is the number of Grid layout Columns in each row.
    recyclerViewLayoutManager = new GridLayoutManager(context, 2);

    recyclerView.setLayoutManager(recyclerViewLayoutManager);

    recyclerView_Adapter = new RecyclerViewAdapter(context,numbers);

    recyclerView.setAdapter(recyclerView_Adapter);

}
public void setLocale(String lang) {
    Locale myLocale = new Locale(lang);
    Resources res = context.getResources();
    DisplayMetrics dm = res.getDisplayMetrics();
    Configuration conf = res.getConfiguration();
    conf.locale = myLocale;
    res.updateConfiguration(conf, dm);
    Intent refresh = new Intent(this, MainActivity.class);
    startActivity(refresh);
    finish();
}
}

RecyclerViewAdapter.java

    public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder>{

String[] values;
Context context1;

public RecyclerViewAdapter(Context context2,String[] values2){

    values = values2;

    context1 = context2;
}

public static class ViewHolder extends RecyclerView.ViewHolder{

    public TextView textView;

    public ViewHolder(View v){

        super(v);

        textView = (TextView) v.findViewById(R.id.textview1);

    }
}

@Override
public RecyclerViewAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType){

    View view1 = LayoutInflater.from(context1).inflate(R.layout.recycler_view_items,parent,false);

    ViewHolder viewHolder1 = new ViewHolder(view1);

    return viewHolder1;
}

@Override
public void onBindViewHolder(ViewHolder Vholder,final int position){

    Vholder.textView.setText(values[position]);

    Vholder.textView.setBackgroundColor(Color.parseColor("#ffc947"));

    Vholder.textView.setTextColor(Color.BLACK);
    Vholder.textView.setBackgroundResource(R.drawable.rounded_corner);

    Vholder.itemView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            MainActivity aa = new MainActivity();
            if(position == 4){
                aa.setLocale("hi");//calling function
            }
        }
    });

}

@Override
public int getItemCount(){

    return values.length;
}
}

string.xml

   <?xml version="1.0" encoding="utf-8"?>
 <resources>
<string name="app_name">nnn</string>
<string-array name="abc">
    <item>Query</item>
    <item>Answers</item>
    <item>Rate Us</item>
    <item>Change Language</item>
    <item>Logout</item>
</string-array>
</resources>

string.xml(hi)

  <?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="app_name">nnn</string>
<string-array name="abc">
    <item>सवाल पूछें </item>
    <item>उत्तर देखें</item>
    <item>रेटिंग दीजिये</item>
    <item>भाषा बदलें</item>
    <item>बाहर निकलें</item>
</string-array>
</resources>