مشکل اشتراک گذاری متن

سلام به همه

برای اشتراک گذاری متن از کد زیر استفاده کردم اما وقتی در کلاس main میذارم اجرا نمیکنه و زمانی که در کلاس های دیگه میذارم کرش میکنه ممنون میشم کسی راهنمایی کنه

  txtSher = (ImageView) findViewById(R.id.img_stars);

            txtSher.setOnClickListener(new OnClickListener() {

                @Override
                public void onClick(View arg0) {
                    Intent share = new Intent(Intent.ACTION_SEND);
                    share.setType("text/plain");
                    share.putExtra(Intent.EXTRA_TEXT, txt_text.getText());
                    startActivity(Intent.createChooser(share, "اشتراگ بگذارید ... :"));

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 07-15 15:44:57.827: E/AndroidRuntime(1558): java.lang.RuntimeException: Unable to start activity ComponentInfo{book/book.storys}: java.lang.NullPointerException
07-15 15:44:57.827: E/AndroidRuntime(1558): Caused by: java.lang.NullPointerException
07-15 15:44:57.827: E/AndroidRuntime(1558): 	at book.storys.onCreate(storys.java:34)

 اینم کد صفحه storys

 import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;


public class storys extends ListActivity {

    private database db;
    private String[] Name;
    private String[] Star;
    private ImageView         txtSher;
    
    private String   season;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.storys);

        db = new database(this);
        Bundle ex = getIntent().getExtras();
        season = ex.getString("seasone");

        refresher();
        setListAdapter(new AA());

    }


    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        Intent intent = new Intent(storys.this, matn_asli_dastan.class);
        intent.putExtra("seasone", season);
        intent.putExtra("name", Name[position]);
        storys.this.startActivity(intent);

    }


    class AA extends ArrayAdapter<String> {

        public AA() {
            super(storys.this, R.layout.row_storys, Name);
        }


        @Override
        public View getView(final int position, View convertView, ViewGroup parent) {
            LayoutInflater in = getLayoutInflater();
            View row = in.inflate(R.layout.row_storys, parent, false);
            TextView name = (TextView) row.findViewById(R.id.txt_name_story);
            final ImageView star = (ImageView) row.findViewById(R.id.star_of);
            if (Star[position].equals("1")) {
                star.setImageResource(R.drawable.star_on);
            } else {
                star.setImageResource(R.drawable.star_of);
            }

            star.setOnClickListener(new OnClickListener() {

                @Override
                public void onClick(View arg0) {

                    db.open();
                    if (Star[position].equals("1")) {
                        db.broozresani_doostdashtaniha("contents", season, Name[position], "0");
                        star.setImageResource(R.drawable.star_of);
                        Star[position] = "0";
                    } else {
                        db.broozresani_doostdashtaniha("contents", season, Name[position], "1  ");
                        star.setImageResource(R.drawable.star_on);
                        Star[position] = "1";
                    }

                }
            });
            txtSher = (ImageView) findViewById(R.id.img_stars);
            txtSher.setOnClickListener(new OnClickListener() {

                @Override
                public void onClick(View arg0) {
                    Intent share = new Intent(Intent.ACTION_SEND);
                    share.setType("text/plain");
                    share.putExtra(Intent.EXTRA_TEXT, "This is simple text to send ");
                    startActivity(Intent.createChooser(share, "Share with application :"));
                }
            });

            name.setText(Name[position]);
            name.setTypeface(BookxActivity.font);

            return (row);
        }
    }


    private void refresher() {
        db.open();
        int save = db.shomaresh_dastan("contents", season);
        Name = new String[save];
        Star = new String[save];

        for (int i = 0; i < save; i++) {
            Name[i] = db.namayesh_dastan("contents", i, season, 1);
            Star[i] = db.namayesh_dastan("contents", i, season, 4);
        }
        db.open();
    }
}