Question

I have a simple linearlayout with a textbox a button and a listview, I’m doing some URL data getting when something is entered in the textbox and the button is pressed I want to parse the results and display in the listview.

What I can’t work out is how to instatiate the listview from within my extende activity class and add it to the layout? I think I’m barking up the wrong tree !

public class HelloAndroid extends Activity{
    /** Called when the activity is first created. */
    @Override

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);

        MyList L;
        L = new MyList();

        //setContentView(L.getListView());

        EditText edittext = (EditText)findViewById(R.id.editText1);
        edittext.setText("");


        Button button = (Button)findViewById(R.id.button1);
        button.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                try {
                    EditText edittext = (EditText)findViewById(R.id.editText1);
                    executeHttpGet(edittext.getText().toString());
                } catch (Exception e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } 
            }
        });  
    }

    public void executeHttpGet(String vrm) throws Exception {
        BufferedReader in = null;
        try {
            HttpClient client = new DefaultHttpClient();
            HttpGet request = new HttpGet();
            request.setURI(new URI("http://xxx/vrmtest.asp?vrm="+vrm));
            HttpResponse response = client.execute(request);
            in = new BufferedReader
            (new InputStreamReader(response.getEntity().getContent()));
            StringBuffer sb = new StringBuffer("");
            String line = "";
            String NL = System.getProperty("line.separator");
            while ((line = in.readLine()) != null) {
                sb.append(line + NL);
            }
            in.close();
            String page = sb.toString();
            System.out.println(page);

            Context context = getApplicationContext();
            CharSequence text = page;
            int duration = Toast.LENGTH_LONG;


            Toast toast = Toast.makeText(context, text, duration);
            toast.show();            

            } finally {
            if (in != null) {
                try {
                    in.close();
                    } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    public class MyList extends ListActivity {

        /** Called when the activity is first created. */
        public void onCreate(Bundle icicle) {
            super.onCreate(icicle);
            // Create an array of Strings, that will be put to our ListActivity
            String[] names = new String[] { "Linux", "Windows7", "Eclipse", "Suse",
                    "Ubuntu", "Solaris", "Android", "iPhone"};
            // Create an ArrayAdapter, that will actually make the Strings above
            // appear in the ListView
            this.setListAdapter(new ArrayAdapter<String>(this,
                    android.R.layout.simple_list_item_1, names));
        }

        @Override
        protected void onListItemClick(ListView l, View v, int position, long id) {
            super.onListItemClick(l, v, position, id);
            // Get the item that was clicked
            Object o = this.getListAdapter().getItem(position);
            String keyword = o.toString();
            Toast.makeText(this, "You selected: " + keyword, Toast.LENGTH_LONG)
                    .show();
        }
    }    
}

An explanation would suffice rather than code but an example would be nice.

Answer 1

As long as your main.xml layout file has a ListView in it, you’re on the right path. Set its @+id to something arbitrary and reference it in your code with:

ListView lv = (ListView) findViewById(R.id.arbitrary_id);

You don’t necessarily need a ListActivity to use a ListView. Simply parse the data that you receive back from the server, put it in an array, and use lv.setAdapter(your_array_adapter) to fill the ListView with your data.

You can go further and specify your ItemClickListener by:

lv.setOnItemClickListener(new OnItemClickListener() {
    @Override
    public void onItemClick(AdapterView<?> a, View v, int position, long id) {
    }
};

Alternatively, you can create the ListView programmatically using

ListView lv = new ListView(this);

and adding it to a view in your layout with

some_container_view_in_main.addView(lv);

Then you would set the ArrayAdapter and OnItemClickListener the same as above.