android - 在 onChildClick() 方法之外的 Expandable ListView Android 中更改被点击子项的背景颜色

Question

我有一个 Activity 和两个 fragment - Fragment1 和 Fragment2。当应用程序启动时，Fragment1 附加到我的 Activity ，此 fragment 由一个 ExpandableListView 组成。当我单击任何子项时，它会更改 subview 的背景颜色，并且 Fragment1 会被 Fragment2 替换。当我从 Fragment2 返回到 Fragment 1 时，它应该会显示已更改的 childView 背景颜色。如何实现它？

这就是我所做的，我的 fragment 1 代码:-

     @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState)
        {

            View view = inflater.inflate(R.layout.rooms_frag, container, false);
            ExpandableListView expandableListView = (ExpandableListView)view.findViewById(R.id.exp_list);
            MoviesAdapter adapter = new MoviesAdapter(getActivity());
            expandableListView.setAdapter(adapter);
            if(flag)
            {
                flag = false;
            }
            else
            {

                Toast.makeText(getActivity(),""+ MainActivity.grpPosition,Toast.LENGTH_SHORT).show();
                expandableListView.expandGroup(MainActivity.grpPosition);
               // myView is a static TextView declared in the fragment class itself                
                myView.setBackgroundColor(Color.rgb(245, 245, 245));//Here I have tried to change the background color but does not get changed(No errors or warnings either)
            }
            expandableListView.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {

                @Override
                public boolean onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id) {
                    MainActivity.grpPosition = groupPosition;
                    MainActivity.chldPosition = childPosition;
                    SpotlightsFragment myFrag = new SpotlightsFragment();
                    String childName = parent.getExpandableListAdapter().getChild(groupPosition, childPosition).toString();
                    String parentName = parent.getExpandableListAdapter().getGroup(groupPosition).toString();
                    TextView childView = (TextView) v.findViewById(R.id.child_txt);
                    myView = childView;
                    childView.setBackgroundColor(Color.rgb(245, 245, 245));
                   return false;
            }
        });
        return  view;
    }

fragment 2:-

backButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
        Fragment1 myFrag = new Fragment1();
        FragmentTransaction transaction = MainActivity.fragmentManager.beginTransaction();
        transaction.replace(R.id.frag, myFrag);
        transaction.commit();
                }
            });

Answer 1

首先，我建议由 Activity (在本例中为 MainActivity)管理 fragment 之间的转换。一个 fragment 越少越好。

您应该创建一个接口(interface)，让 Activity 实现该接口(interface)，第二个 fragment 将通过转换为该接口(interface)的 getActivity() 调用接口(interface)方法。在界面中，您可以在 fragment 之间切换。

应该是这样的

返回列表.java

public interface GoBackToList {
    public void andHighlightPosition(int group, int position);
}

主 Activity .java

public class MainActivity implements GoBackToList {
    ...
    private Fragment1 f1;

    @Override
    public void andHighlightPosition(int group, int position) {
        FragmentTransaction transaction = fragmentManager.beginTransaction();
        transaction.replace(R.id.frag, f1);
        transaction.commit();
        f1.highlight(group, position);
    }
}

fragment 1.java

public class Fragment1 extends Fragment {
    ...
    private int previousHighlightGroup;
    private int previousHighlightPosition;

    public void highlight(int group, int position) {
    // Reset previous highlight color
    expandableListView.getExpandableListAdapter().getChild(previousHighlightGroup, previousHighlightPosition)
            .findViewById(R.id.child_txt).setBackgroundColor(ORIGINAL_COLOR);
    // Highlight new view
    expandableListView.getExpandableListAdapter().getChild(group, position)
            .findViewById(R.id.child_txt).setBackgroundColor(HIGHLIGHT_COLOR);
    // Store values
    previousHighlightGroup = group;
    previousHighlightPosition = position;
   }
}

fragment 2.java

backButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
        ((GoBackToList)getActivity())).andHighlight(currentGroup, currentPosition);
        }
     });