Question

i’ve just started playing around with android and i followed a layout tutorial about customizing a ListView layout on this website.

Since all the list are populated using arrays and all share the same id –>(R.id.ListViewId), i was wondering that how do i implement an onItemClick listener on each individual color? I’m trying to create an activity for each color, like for example if i click on Red, it will start a new activity, and if i click on Blue, it will start a different activity etc.

XML

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:orientation="vertical"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent">
    <ListView
       android:id="@+id/ListViewId"
       android:layout_width="fill_parent"
       android:layout_height="wrap_content"/>
</LinearLayout>

Java

import android.app.Activity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.ListView;

public class ColorList extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        String[] items = {"red", "blue","green"};

        ListView listView = (ListView) findViewById(R.id.ListViewId);
        listView.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, items));
    }
}

This is what i’ve tried….but i can’t figure out how to do it…any ideas? Please.

        ListView listView = (ListView) findViewById(R.id.ListViewId);
        listView.setAdapter(new UserItemAdapter(this, android.R.layout.simple_list_item_1, users));
        listView.setTextFilterEnabled(true);
        listView.setOnItemClickListener(new OnItemClickListener() {

          @Override
          public void onItemClick(AdapterView<?> a, View v, int pos, long id){
              // some code here to start a new activity
              // the code below is just for testing, on click it will show a NullPointerException error
              Object o = null;
              o.toString();
          }
      });

Answer 1

Your onItemClick is provided both the view itself and the position within the list; you need to use one of these to determine the information you want. In your simply example, position will be 0, 1, or 2 for “red”, “blue”, and “green”. In a more complicated example, you can override creation of the view within your code and you can use setTag() to attach details you may need later (if position is not sufficient).