Question

I am fairly new to Android programming and trying to set items in a listview upon loading the information from internal storage.

I have two global arrays that I am using: first one is a String array that has the names of the items in the list, and the second is a boolean array that keeps track of which items are crossed out. I am using a TextView in the listview.

main_activity.xml:

<ListView
        android:id="@+id/listViewMyList"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >
</ListView>

rowlayout.xml:
<TextView
    android:id="@+id/label"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="3dp"
    android:layout_marginBottom="3dp"
    android:text="@+id/label" />

I have created an onClickListener() which successfully updates the state of each list item:

public class MainActivity extends Activity
{
// Initialize the list (global list values)
String[] values = new String[0]; // array of items for the list
boolean[] checkedVals = new boolean[0]; // keep track of which items are crossed-off
String localFileName = "myListData.csv";

@Override
public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    // read the data from file if present
    readListFromFile();        

    // find the ListView
    ListView lst = (ListView) findViewById(R.id.listViewMyList);

    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
            R.layout.rowlayout, R.id.label, values);
    lst.setAdapter(adapter);

    // define what happens on click
    lst.setOnItemClickListener(new OnItemClickListener()
    {
          public void onItemClick(AdapterView<?> parent, View view,int position, long id)
          {
              // read crossed status and set text flags for strikethrough                 
              if (checkedVals[position])
              {                   
                  TextView text1 = (TextView)view.findViewById(R.id.label);
                  text1.setPaintFlags(text1.getPaintFlags() & ~Paint.STRIKE_THRU_TEXT_FLAG);
                  text1.setTextColor(0xff000000);
                  checkedVals[position] = false;
              }
              else
              {
                  TextView text1 = (TextView)view.findViewById(R.id.label);
                  text1.setPaintFlags(text1.getPaintFlags() | Paint.STRIKE_THRU_TEXT_FLAG);
                  text1.setTextColor(0xff888888);
                  checkedVals[position] = true;
              }
              // save the data in a file
              saveListToFile();
          }
    });

}

So this code works fine for crossing out and un-crossing out the items. I don’t know how can I cross-out some of the items (determined by the checkedVals boolean array) without clicking or any activity when I load the list.

Thanks in advance.

Answer 1

You need to create a custom Adapter by extending ArrayAdapter and overriding getView().

The getView() method loads every row’s layout, this is where you should check if the row is in your checkedVals array and draw with the appropriate flags. This Google Talk by an Android lead programmer, Romain Guy, provide a wealth of information about best practices on how to do this.