在我的应用程序中，我想在TabLayout中以编程方式创建标签，以便在Fragments中设置ViewPager。
我想：如果 celebrityCount＆gt; 0 显示 celebritiesFragments，如果 celebrityCount＆lt; 0 不显示此片段更多...
为此，我写下代码：
FullSearchSendData sendData = new FullSearchSendData();
sendData.setKey(fullSearchText);
sendData.setLoadImages(true);
sendData.setSearchInCelebrities(true);
sendData.setSearchInMovies(true);
sendData.setSearchInSeries(true);
sendData.setSearchInEpisodes(false);
sendData.setSearchInUsers(true);
sendData.setPageIndex(1);
sendData.setPageSize(10);
sendData.setMaxDistance(1);
fullSearch_LoadLay.setVisibility(View.VISIBLE);
InterfaceApi api = ApiClient.getClient().create(InterfaceApi.class);
Call<FullSearchResponse> call = api.getFullSearch(sendData);
call.enqueue(new Callback<FullSearchResponse>() {
@Override
public void onResponse(Call<FullSearchResponse> call, Response<FullSearchResponse> response) {
FullSearchResponse searchResponse = response.body();
if (searchResponse.getData().getCelebritiesCount() > 0) {
celebritiesCount = searchResponse.getData().getCelebritiesCount();
celebrityList.clear();
celebrityList.addAll(searchResponse.getData().getCelebrities());
} else {
}
if (searchResponse.getData().getMoviesCount() > 0) {
movieCount = searchResponse.getData().getMoviesCount();
movieList.clear();
movieList.addAll(searchResponse.getData().getMovies());
} else {
}
if (searchResponse.getData().getSeriesCount() > 0) {
serieCount = searchResponse.getData().getSeriesCount();
seriesList.clear();
seriesList.addAll(searchResponse.getData().getSeries());
} else {
}
if (searchResponse.getData().getUsersCount() > 0) {
usersCount = searchResponse.getData().getUsersCount();
userList.clear();
userList.addAll(searchResponse.getData().getUsers());
} else {
}
///////////
adapter = new FragmentPagerAdapter(getSupportFragmentManager()) {
@Override
public Fragment getItem(int position) {
Fragment fragment = null;
switch (position) {
case 0:
if (celebritiesCount > 0)
fragment = FullSearchCelebritiesFragment.getInstance(celebrityList, celebritiesCount, fullSearchText);
break;
case 1:
if (movieCount > 0)
fragment = FullSearchMovieFragment.getInstance(movieList, movieCount, fullSearchText);
break;
case 2:
if (serieCount > 0)
fragment = FullSearchSeriesFragment.getInstance(seriesList, serieCount, fullSearchText);
break;
case 3:
if (usersCount > 0)
fragment = FullSearchUsersFragment.getInstance(userList, usersCount, fullSearchText);
break;
}
return fragment;
}
@Override
public CharSequence getPageTitle(int position) {
String title = null;
switch (position) {
case 0:
if (celebritiesCount > 0)
title = "Celebrities";
break;
case 1:
if (movieCount > 0)
title = "Movies";
break;
case 2:
if (serieCount > 0)
title = "Series";
break;
case 3:
if (serieCount > 0)
title = "Users";
break;
}
return title;
}
@Override
public int getCount() {
int count = 0;
if (celebritiesCount > 0) {
count = 1;
}
if (movieCount > 0) {
count = 2;
}
if (serieCount > 0) {
count = 3;
}
if (usersCount > 0) {
count = 4;
}
return count;
}
};
///////////
fullSearch_ViewPager.setAdapter(adapter);
fullSearch_tabLayout.setupWithViewPager(fullSearch_ViewPager);
fullSearch_tabLayout.setTabMode(TabLayout.MODE_FIXED);
fullSearch_LoadLay.setVisibility(View.GONE);
}
@Override
public void onFailure(Call<FullSearchResponse> call, Throwable t) {
fullSearch_LoadLay.setVisibility(View.GONE);
fullSearch_ReloadLay.setVisibility(View.VISIBLE);
}
});
但是告诉我这个错误：
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Class java.lang.Object.getClass()' on a null object reference
at android.support.v4.app.BackStackRecord.doAddOp(BackStackRecord.java:380)
at android.support.v4.app.BackStackRecord.add(BackStackRecord.java:375)
at android.support.v4.app.FragmentPagerAdapter.instantiateItem(FragmentPagerAdapter.java:103)
at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:1034)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1182)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1116)
at android.support.v4.view.ViewPager.setAdapter(ViewPager.java:540)
at in.app.test.Activities.FullSearch$1.onResponse(FullSearch.java:208)
at retrofit2.ExecutorCallAdapterFactory$ExecutorCallbackCall$1$1.run(ExecutorCallAdapterFactory.java:68)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5349)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:908)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:703)
我该如何解决？请帮帮我
答案 0 :(得分：0)
您需要使用 addTab（）方法 TabLayout 添加标签
以下是示例代码：
private void setUpTab() {
viewPagerAdapter = new ViewPagerAdapter(getSupportFragmentManager(), this);
for (int i = 0; i < viewPagerAdapter.getCount(); i++) {
tabLayout.addTab(
tabLayout.newTab()
.setText(viewPagerAdapter.getPageTitle(i)));
}
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
viewPager.setAdapter(viewPagerAdapter);
}