Twice opening activity with an null value

问题

i have an activity with some buttons in which when you click on any of buttons First with Intent send a value to another activity that contains a list view is filled with database. And I want to use this value as a parameter for where command select for filling list view with special Content

now i have a problem that when run program and when click on a button, first open a empty list view and after clicking back-button, list view is correctly displayed data.

Where is my mistake?

source MainActivity

---

final Intent i = new Intent(MainActivity.this,ListActivity.class);

    btn_irani.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {

            i.putExtra("position","ایران");
            startActivity(i);

            startActivity(GoToList);

        }
    });


    btn_turkie.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
              i.putExtra("position","ترکیه");
                startActivity(i);
            startActivity(GoToList);

        }
    });

source ListActivity

---

public class ListActivity extends Activity {





    String value = "";
    MovieDB myDbHelper;
    SQLiteDatabase db;
    ListAdapter adapter;
    ArrayList<HashMap<String, String>> data;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.list_layout);






        value = getIntent().getStringExtra("position");


        ListView lst=(ListView) findViewById(R.id.listView1);
        Load_Database();
        db = myDbHelper.getReadableDatabase();



        Cursor  c = db.rawQuery("select * from movie_list where product = '"+value+"'", null);

            data = new ArrayList<HashMap<String, String>>();

            for (; c.moveToNext();) {
                HashMap<String, String> map = new HashMap<String, String>();
                String img = c.getString(c.getColumnIndex("img"));
                String name = c.getString(c.getColumnIndex("name"));
                map.put("img", img);
                map.put("name", name);
                data.add(map);
            }
            adapter = new ListMovie(this, data);

            lst.setAdapter(adapter);

    }

Please Help me!

回答1:

I think you have called startActivity() twice by mistake. If you want to send a value to your next Activity while calling it once startActivity() is sufficient.

来源：https://stackoverflow.com/questions/28799958/twice-opening-activity-with-an-null-value