I’m facing with a big problem with the ExpandableListView.
My goal is to let user change item’s position into this single selection expandable list view:
When an user clicks on an item, the item becomes checked and a context action bar appears.
So user can move up or down an item in this way:
The move up/down function that i’ve implemented works fine (it’s based on swap position over an ArrayList, that’s the datasource of my BaseExpandableListAdapter, and notify changes to the UI). Unfortunately when i move a checked item, it looses the checked state…and if i move the item out of the visible bounds (in the example, after “Locked” or before “Attachements” view) the expandablelistview doesn’t scroll to the new position.
How can i achieve that?
Below, my “moveDownFocusedItem()” coded into my custom Adapter class:
//This class is ok!
//Contains Group and Child position of an ExpandableListView
public class Position{
int GroupPosition;
int ChildPosition;
public boolean isChild(){
return (ChildPosition != AbsListView.INVALID_POSITION);
}
public Position getPreviousPosition(){
if(ChildPosition==AbsListView.INVALID_POSITION)
if(GroupPosition>0)
return new Position(GroupPosition-1);
else
return null;
else
if(ChildPosition>0)
return new Position(GroupPosition, ChildPosition-1);
else
return null;
}
public Position getNextPosition(){
if(ChildPosition==AbsListView.INVALID_POSITION)
if(GroupPosition<_fieldConfigurationList.size()-1)
return new Position(GroupPosition+1);
else
return null;
else
if(ChildPosition<_fieldConfigurationList.get(GroupPosition).getChildren().size()-1)
return new Position(GroupPosition, ChildPosition+1);
else
return null;
}
public Position(int groupPosition){
this.GroupPosition = groupPosition;
this.ChildPosition = AbsListView.INVALID_POSITION;
}
public Position(int groupPosition, int childPosition){
this.GroupPosition = groupPosition;
this.ChildPosition = childPosition;
}
}
public void moveDownFocusedItem(){
//This function returns the next position to move to
//(_focusedPosition is the current checked item position)
Position nextPosition = this._focusedPosition.getNextPosition();
//Swap ArrayList (This works!)
if(nextPosition!=null){
Collections.swap(this._fieldConfigurationList, //that's my datasource
this._focusedPosition.GroupPosition, //Start position for swapping
nextPosition.GroupPosition); //Destination position for swapping
//Set the new focused position (This works!)
this._focusedPosition = nextPosition;
//TODO:
//Now i have to call "SetItemChecked()" method to uncheck old focused position and check the new one.
//How to do it? How can i get the required "position" argument from _focusedPosition.GroupPosition and _focusedPosition.ChildPosition?
//And also...if the focused view has moved to an invisible position (such as the end of the expandablelistview) how can i scroll
//to this position?
//Notify changes (This works!)
this.notifyDataSetChanged();
}
}
After studying the code behind the expandablelistview, i found a fairly simple way to the required task. I ‘ll publish part of my adapter that allows to check a listview items and move it up and down.
Remember:
1) make sure your expandablelistview is in “single selection” mode (ExpandableListView.setChoiceMode(AbsListView.CHOICE_MODE_SINGLE);)
2) Your custom row view has android:descendantFocusability=”blocksDescendants”
I’ve done several tests on android J.B and seems to work correctly without errors or memory leaks.
In case of bugs, please post improovements or fixes.
This is my code:
}