Question

我有一个Activity和两个片段 - Fragment1和Fragment2。当应用程序启动Fragment1附加到我的活动时，此片段包含一个ExpandableListView。当我点击任何一个孩子时，它会改变子视图的背景颜色，Fragment1会被Fragment2取代。当我从Fragment2回到Fragment一时，它应该显示改变的childView背景颜色。我该如何实现它？

这就是我所做的，我的片段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;
    }

Fragment2： -

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，我建议在活动管理的片段之间进行转换（在本例中为MainActivity）。至少一个片段知道另一个，越好。

你应该创建一个接口，使活动实现该接口，第二个片段将通过getActivity（）调用接口方法到该接口。在界面中，您可以在片段之间进行更改。

这就是这样的

GoBackToList.java

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

MainActivity.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);
    }
}

Fragment1.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;
   }
}

Fragment2.java

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

Answer 2

当您用第二个片段替换第一个片段时，您应该在 onSaveInstanceState() 中存储所需的索引。这样，当您返回片段时再次创建片段时，可以在 savedInstanceState 捆绑包中找到该索引。然后，使用该索引，您可以设置该项目的颜色。

在onChildClick（）方法

2 个答案: