Question

In my app I get a Force Close, and I don’t know how to solve this. The problem is that I have a class that extends ListActivity. In this class there is a list of shops, and the user should select one of the shops. If he not select a shop and press button Back I get Force Close, because the previous class expect the name of the shop. How can I catch this error?

Here is my class for selecting a shop :

public class SelectShop extends ListActivity {

private ListView lv1;
SimpleCursorAdapter adapter = null;
Cursor cursor;
DbAdapter db;
ImageView iconshop;

private static final int ADD=Menu.FIRST;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.shopselect);

    iconshop = (ImageView) findViewById(R.id.iconshop);
    lv1 = getListView();

    DbApplication myApplication = (DbApplication) this.getApplication();
    db= myApplication.getDatabaseAdapter();

    cursor = db.getAllShops();
    startManagingCursor(cursor);
    if (cursor != null && cursor.moveToFirst()){
    adapter = new SimpleCursorAdapter(this, R.layout.shopsrow, cursor,
            new String[] { DbAdapter.NAME, DbAdapter.ADRESS }, new int[] {
                    R.id.title, R.id.address });

    setListAdapter(adapter);
    }else Toast.makeText(this,
            "Choose Menu for adding a shop",
            Toast.LENGTH_LONG).show();

    lv1.setOnItemClickListener(new OnItemClickListener() {

        public void onItemClick(AdapterView<?> parent, View v,
                int position, long id) {
            Intent j = new Intent(SelectShop.this,
                    com.ShoppingList.NewList.class);

            Cursor c = (Cursor) parent.getAdapter().getItem(position);
            j.putExtra("shop", c.getString(c.getColumnIndex(db.NAME)));
            setResult(RESULT_OK, j);
            finish();
        }
    });
}
/*Adaugarea meniului Add Shop*/
public boolean onCreateOptionsMenu(Menu menu) { 
    menu.add(0, ADD, 0, "Add Shop").setIcon(R.drawable.additem); 
    return true; 
    }

public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    case ADD:
        Intent j = new Intent(SelectShop.this, Shops.class);
        startActivityForResult(j, 0);
        return true;
    }
    return false;
}

}

and in previuos class I have this:

public void onActivityResult(int requestCode, int resultCode, Intent intent) {
        super.onActivityResult(requestCode, resultCode, intent);
        switch (requestCode) {
        case 0: {
            Bundle b = intent.getExtras();
            shopselect = b.getString("shop");
            shop.setText(shopselect);
        }
            break;
}
}

Answer 1

I think you need to implement a mechanism that won’t let your user get back to previous activity without choosing any item in the list. Override your onKeyDown() method, and when the user presses Back key you should check whether any item is chosen. If it’s not you can throw an alert dialog to inform user what he must do to proceed. Hope this helps!