problem - populate database into listview in android

Question

hi all i need to populate database elements in listview. i get null pointer exception and array adapter errors. i did the following ways: 1)created a string array with size of number of rows 2) stored database values in array 3)merge in listview . i tried long time but i cannot find it. in coding:

    Cursor c = db.rawQuery("select * from stopwatch"  , null);
    if (c != null ) {
    if  (c.moveToFirst()) {
      do {
        counter=counter+1;   // finding no of rows in table.
      }while (c.moveToNext());
    }
    } 
    array=new String[counter];


    counter1=0;
    Cursor c1 = db.rawQuery("select * from stopwatch"  , null);
    if (c1 != null ) {
    if  (c1.moveToFirst()) {
      do {
           array[counter1]=String.valueOf(c1.getInt(0))+":"+String.valueOf(c1.getInt(1))+":"+String.valueOf(c1.getInt(2));

counter=counter+1; }while (c1.moveToNext()); } } db.close();

    // populating in listview as follows
     list1.setAdapter(new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, array));

my logcat:

   05-12 18:52:30.853: ERROR/AndroidRuntime(8330): java.lang.NullPointerException
 05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:351)
 05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.widget.ArrayAdapter.getView(ArrayAdapter.java:323)
   05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.widget.AbsListView.obtainView(AbsListView.java:1254)
  05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.widget.ListView.measureHeightOfChildren(ListView.java:1142)
  05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.widget.ListView.onMeasure(ListView.java:1055)
   05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.view.View.measure(View.java:7117)
   05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:2929)
  05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:888)
  05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.widget.LinearLayout.measureHorizontal(LinearLayout.java:619)
   05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at  android.widget.LinearLayout.onMeasure(LinearLayout.java:280)
  05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.view.View.measure(View.java:7117)
 05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:2929)
05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:245)
 05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.view.View.measure(View.java:7117)
 05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.widget.LinearLayout.measureVertical(LinearLayout.java:464)
  05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:278)
  05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.view.View.measure(View.java:7117)
  05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:2929)
  05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:245)
  05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.view.View.measure(View.java:7117)
  05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.view.ViewRoot.performTraversals(ViewRoot.java:713)
  05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.view.ViewRoot.handleMessage(ViewRoot.java:1504)
  05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.os.Handler.dispatchMessage(Handler.java:99)
   05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at  android.os.Looper.loop(Looper.java:123)
  05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at android.app.ActivityThread.main(ActivityThread.java:3948)
 05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at java.lang.reflect.Method.invokeNative(Native Method)
 05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at  java.lang.reflect.Method.invoke(Method.java:521)
 05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:782)
 05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:540)
 05-12 18:52:30.853: ERROR/AndroidRuntime(8330):     at dalvik.system.NativeStart.main(Native Method)

BadSkillz · Accepted Answer · 2011-05-12 14:19:05Z

Try using the SQLiteOpenHelper to create a datahelper

implement a function like so:

public List<List<String>> getData(){
       Cursor cursor = this.db.query(TABLE_NAME,new String[] { "value1", "value2" }, null, null, null, null, "code asc");
       List<List<String>> list = new ArrayList<List<String>>();
       if (cursor.moveToFirst()){
           do{
               List<String> temp = new ArrayList<String>();
               temp.add(cursor.getString(0));
               temp.add(cursor.getString(1));
               list.add(temp);
           }while (cursor.moveToNext());
       }
       return list;
   }

then in the other class call:

private List<List<String>> liItems;
liItems = dh.getData();

/** create an array in the proper length */
String[] rgItems = new String[liItems.size()];

/** Fill the array with data */
for (int i=0; i < liItems.size(); i++){
        List<String> temp = liItems.get(i);
        rgItems[i] = temp.get(0) + " - " + temp.get(1);
    }
    /** Populate ListView with list */
    ArrayList<String> customerList = new ArrayList<String>();
    customerList.addAll( Arrays.asList(rgItems) );
    adItemAdapter = new ArrayAdapter<String>(this, R.layout.itemlisttext, rgItems);
    lvItemListview.setAdapter(adItemAdapter);

itemlisttext is a xmlLayout with textview

This works fine for me, hope it helps you.

Community · Accepted Answer · 2017-05-23 11:55:36Z

0

Well you have used counter to count record. use cursor.getCount();

And use SimpleCursorAdapter instead of ArrayAdapter. It will facilitate you.

Have a look at this Answer

edited May 23, 2017 at 11:55

CommunityBot

11 silver badge

answered May 12, 2011 at 14:17

Adil Soomro

37.7k9 gold badges105 silver badges155 bronze badges

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