我的微调器出现问题

Question

So i'm starting a application and the first thing to do is make a description of a city when the city is selected. I can show the description but it make the description of all the cities on the same time and it don't come out when i select another city : it add more and more .

this is my code :

public class Main extends Activity implements OnItemClickListener, OnItemSelectedListener {

TextView description;
Spinner spin;
ArrayAdapter adapter_city;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);


    description = (TextView)findViewById(R.id.description);

    spin = (Spinner)findViewById(R.id.spin);

    adapter_city = ArrayAdapter.createFromResource(this, R.array.Cities, android.R.layout.simple_spinner_item);
    adapter_city.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spin.setAdapter(adapter_city);
    spin.setOnItemSelectedListener(this);
}
@Override
public void onItemClick(AdapterView<?> parent, View v, int position, long id) {


}
@Override
public void onItemSelected(AdapterView<?> parent, View v, int position,
        long id) {
    switch(position){

    case 0 :    description.append(getString(R.string.Paris));

    case 1 :    description.append(getString(R.string.Chicago));

    case 2 :    description.append(getString(R.string.NewYork));
    }




}
@Override
public void onNothingSelected(AdapterView<?> parent) {

}

thank you .

Answer 1

Try using description.setText(CharSequence text) instead of append. Append is for appending text.

Answer 2

Instead of:

description.append(getString(R.string.Paris));

Why don't you just use:

description.setText(R.string.Paris);

Here is what it should look like:

case 0 :    description.setText(R.string.Paris);
            break;

case 1 :    description.setText(R.string.Chicago);
            break;

case 2 :    description.setText(R.string.NewYork);
            break;

Answer 3

You need to add break s after every case or execution will continue to all of them when matched:

    switch(position){

case 0 :    description.setText(R.string.Paris); break;

case 1 :    description.setText(R.string.Chicago); break;

case 2 :    description.setText(R.string.NewYork); break;
}