Question

我是app开发的新手。我目前正在使用tabview和其中一个标签中的ExpandableListView开发应用程序，这就是为什么我要尝试在片段中使用expandablelistview。

直接从活动中运行时，我的expandablelistview看起来完美无缺，但是当我尝试从片段运行它时，它显示为空白。

HomeFragment.java

public class HomeFragment extends Fragment {

ExpandableListView expandableListView;
View homeFragmentView;


public HomeFragment() {
    // Required empty public constructor
}

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

    homeFragmentView = inflater.inflate(R.layout.fragment_home, container, false);
    expandableListView = (ExpandableListView) homeFragmentView.findViewById(R.id.exp_listview);


    return homeFragmentView;

}

@Override
public void onViewCreated(View v, Bundle savedInstanceState){

    List<String> Headings = new ArrayList<String>();
    List<String> L1 = new ArrayList<String>();
    List<String> L2 = new ArrayList<String>();
    List<String> L3 = new ArrayList<String>();
    HashMap<String, List<String>> ChildList = new HashMap<String, List<String>>();
    String heading_items[] = getResources().getStringArray(R.array.header_titles);
    String h1[] = getResources().getStringArray(R.array.h1_items);
    String h2[] = getResources().getStringArray(R.array.h2_items);
    String h3[] = getResources().getStringArray(R.array.h3_items);

    for(String title : heading_items){
        Headings.add(title);
    }
    for (String title : h1){
        L1.add(title);
    }
    for (String title : h2){
        L2.add(title);
    }
    for (String title : h3){
        L3.add(title);
    }
    ChildList.put(Headings.get(0), L1);
    ChildList.put(Headings.get(1), L2);
    ChildList.put(Headings.get(2), L3);

    ExpListViewAdapter expListViewAdapter = new ExpListViewAdapter(getActivity(), Headings, ChildList);
    expandableListView.setAdapter(expListViewAdapter);


}
}

适配器类：

public class ExpListViewAdapter extends BaseExpandableListAdapter {

private List<String> header_titles;
private HashMap<String, List<String>> child_titles;
private Context ctx;

ExpListViewAdapter(Context ctx, List<String> header_titles, HashMap<String, List<String>> child_titles){
    this.ctx = ctx;
    this.child_titles = child_titles;
    this.header_titles = header_titles;
}



@Override
public int getGroupCount() {
    return header_titles.size();
}

@Override
public int getChildrenCount(int groupPosition) {
    return child_titles.get(header_titles.get(groupPosition)).size();
}

@Override
public Object getGroup(int groupPosition) {
    return header_titles.get(groupPosition);
}

@Override
public Object getChild(int groupPosition, int childPosition) {
    return child_titles.get(header_titles.get(groupPosition)).get(childPosition);
}

@Override
public long getGroupId(int groupPosition) {
    return groupPosition;
}

@Override
public long getChildId(int groupPosition, int childPosition) {
    return childPosition;
}

@Override
public boolean hasStableIds() {
    return false;
}

@Override
public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
    String title = (String)this.getGroup(groupPosition);
    if (convertView == null){
        LayoutInflater layoutInflater = (LayoutInflater) this.ctx.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = layoutInflater.inflate(R.layout.parent_layout, null);
    }
    TextView textView = (TextView) convertView.findViewById(R.id.heading_item);
    textView.setTypeface(null, Typeface.BOLD);
    textView.setText(title);

    return convertView;
}

@Override
public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
    String title = (String)this.getChild(groupPosition,childPosition);

    if (convertView == null){
        LayoutInflater layoutInflater = (LayoutInflater) this.ctx.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = layoutInflater.inflate(R.layout.child_layout, null);
    }

    TextView textView = (TextView) convertView.findViewById(R.id.child_item);
    textView.setText(title);

    return convertView;
}

@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
    return true;
}
}

标题（父级）布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="50dp"
android:background="#151515">

<TextView
    android:id="@+id/heading_item"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:text="Hello World"
    android:textColor="#ffffff"
    android:textSize="25dp"
    android:gravity="center_vertical"
    android:layout_marginLeft="10dp"


    />

</LinearLayout>

子布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="50dp"
    android:background="#252525">

    <TextView
        android:id="@+id/child_item"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="Hello World"
        android:textColor="#f9f9f9"
        android:gravity="center_vertical"
        android:textSize="20dp"
        android:layout_marginLeft="10dp"
        />
</LinearLayout>

MainActivity.java

public class MainActivity extends AppCompatActivity {



    Toolbar toolbar;
    TabLayout tabLayout;
    ViewPager viewPager;
    ViewPagerAdapter viewPagerAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        overridePendingTransition(R.anim.slide_in, R.anim.slide_out);

        toolbar = (Toolbar) findViewById(R.id.toolBar);
        setSupportActionBar(toolbar);

        tabLayout = (TabLayout) findViewById(R.id.tabLayout);
        viewPager = (ViewPager) findViewById(R.id.viewPager);
        viewPagerAdapter = new ViewPagerAdapter(getSupportFragmentManager());

        viewPagerAdapter.addFragments(new HomeFragment(), "Home");
        viewPagerAdapter.addFragments(new Group_Invites(), "Group invites");
        viewPagerAdapter.addFragments(new New_Group(), "New group");
        viewPager.setAdapter(viewPagerAdapter);
        tabLayout.setupWithViewPager(viewPager);
    }
}

ViewPagerAdapter.java

public class ViewPagerAdapter extends FragmentPagerAdapter {

    ArrayList<Fragment> fragments = new ArrayList<>();
    ArrayList<String> tabTitles = new ArrayList<>();

    public void addFragments(Fragment fragments, String titles){

        this.fragments.add(fragments);
        this.tabTitles.add(titles);

    }

    public ViewPagerAdapter(FragmentManager fm){
        super (fm);
    }

    @Override
    public Fragment getItem(int position) {

        return fragments.get(position);
    }

    @Override
    public int getCount() {
        return fragments.size();
    }

    @Override
    public CharSequence getPageTitle(int position){
        return tabTitles.get(position);
    }
}

Answer 1

我尝试了你的代码，它工作正常。同时分享您打开片段类的活动代码。

片段

1 个答案: