ListView Updating a single row

Question

I want to update a single row in my listview with different content once i press a button. I know i can use notifydatasetchanged() but that would update the whole listView.

I have read this answer and it fits perfectly for what I want to do.

I have done a listview with 5 rows and when I press the button I want to update the 4th row with a different text. I dont want to set the text programatically since this is just a dummy project just to see if refreshing a single row is possible and my real project is much more complex than just a textview.

So my question is: can i use getView() to update a single row in a listview?

Here is my code:

my Activity:

public class MainActivity extends Activity {

    public ListView list1;
    public listAdapter adapter;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        list1 = (ListView) findViewById(R.id.my_list);
        adapter = new listAdapter(this);
        list1.setAdapter(adapter);

        Button button1 = (Button) findViewById(R.id.my_button);
        button1.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {
                adapter.setText("Different text");
                View row2Update = list1.getChildAt(3);
                list1.getAdapter().getView(3, row2Update, list1);

            }
        });

    } 

}

My adapter :

public class listAdapter extends BaseAdapter{

    public Activity activity;
    public String text="Normal Text";

    public listAdapter(Activity activity){

        this.activity = activity;
    }

    public void setText(String text){
        this.text = text;
    }

    public int getCount() {
        return 5;
    }

    public Object getItem(int position) {

        return null;
    }

    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return 0;
    }

    public View getView(int position, View convertView, ViewGroup parent) {
        LayoutInflater inflater = activity.getLayoutInflater();
        LinearLayout rowView = (LinearLayout) inflater.inflate(R.layout.row_layout, null);
        TextView textView = (TextView) rowView.findViewById(R.id.row_text);
        textView.setText(text);
        return rowView;
    }

}

This is what the activity looks like:

But when I press my button nothing changes

Answer 1

You cannot call the getView() method of the adapter yourself. The adapter's getView() method is is only called, when

• The listview is create
• when the user scrolls the list view

• when notifysetdatachanged() is called.
  All these are done by the OS. GetView() is called for all the rows in the listview. It is not called for just a single row. So, if you want to change the rows, you have to provide the data again in a String[], ArrayList<> etc
  If you want different text to appear for for a single row, onClick() of a button - you can do this

  public class listAdapter extends BaseAdapter{

  public Activity activity;
  public ArrayList<String> text;
  
  public listAdapter(Activity activity){
  
      this.activity = activity;
  }
  
  public void setText(ArrayList<String> text){
      this.text = text;
  }
  
  public int getCount() {
      return 5;
  }
  
  public Object getItem(int position) {
  
      return null;
  }
  
  public long getItemId(int position) {
      // TODO Auto-generated method stub
      return 0;
  }
  
  public View getView(int position, View convertView, ViewGroup parent) {
      LayoutInflater inflater = activity.getLayoutInflater();
      LinearLayout rowView = (LinearLayout) inflater.inflate(R.layout.row_layout, null);
      TextView textView = (TextView) rowView.findViewById(R.id.row_text);
      textView.setText(text[position]);
      return rowView;
  }
  

  }
  And in your Activity :

  list1 = (ListView) findViewById(R.id.my_list);
  adapter = new listAdapter(this);
  String[] entries={"Normal Text","Normal Text","Normal Text","Normal text","Normal text"};
  ArrayList<String> text=Arrays.asList(entries);
  adapter.setText(text);
  list1.setAdapter(adapter);
  
  Button button1 = (Button) findViewById(R.id.my_button);
  button1.setOnClickListener(new OnClickListener() {
  
      public void onClick(View v) {
         text.set(3,"Different Text");
          adapter.setText(text);
          list1.setAdapter(adapter);
  
      }
  });
  

  
  

  There is another way of doing it also as @Andy suggested in one of the comments :

  listViewPeople.setOnItemClickListener(new ListView.OnItemClickListener() {
          @Override
      public void onItemClick(AdapterView<?> a, View v, int position, long l) {
               //IF YOU WANT TO CHANGE THE CONTENT OF THE ROW CLICKED
         if(position == someNumber) {
                 text.set(position,"different Text");
                 list1.setAdapter(text);
         }
      }
  });
  

Sorry for the bold text. For some reason the CTRL+K is not working for the above code.