Question

I am trying to create an ExpandableListView dynamically in my application. The parent rows display the dates of the next 7 days and I retrieve the children from a web-service. But, fetching and displaying the children are not my problem. I am facing trouble in displaying the parent rows dynamically. I need to display the dates of the next 7 days in the parent rows.

I declared this empty array of strings globally.

private String[] parent = new String[7];

Then, inside onCreate(), I used this code to create the parent array contents.

Calendar cal = Calendar.getInstance();
    String strdate = null;
    SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy");

    int i;
    for(i=0;i<7;i++)
    {

        if (cal != null) {
            strdate = sdf.format(cal.getTime());
            }
            parent[i] = strdate;
           cal.add(Calendar.HOUR_OF_DAY, 24);
    }

But, the activity gives a NullPointerException at MyExpandableListAdapter.getGroupView().

(Maybe because the parent array has not be initialized initially ?)

because the code works when I declare the parent array initally as

private String[] parent = new String[] {"","","".....}; 

Answer 1

My solution : Static Block was the answer to it. I put the code to create the parent array contents inside a static block instead of onCreate() and it works like a charm now.