小编Tom*_*net的帖子

I am building a django web app with a custom user model which extends the AbstractBaseUser. In one of my models I need to use this custom user model:

from accounts.models import User

class History(models.Model):
    user = models.ForeignKey(User)
    job = models.ForeignKey(Job)

When I try to run the python manage.py makemigrations command this error message is outputted:

ImportError: cannot import name User

In my settings.py I do the following to let django know that there is a custom user model:

AUTH_USER_MODEL …

我有一个FragmentPagerAdapter处理获取当前片段,跟踪选项卡数量和设置每个选项卡的选项卡标题.

public class ClothingSectionsPagerAdapter extends FragmentPagerAdapter {

    private String[] mCategories;

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

    public void setContext(Context context) {
        mCategories = context.getResources().getStringArray(R.array.category);
    }

    @Override
    public Fragment getItem(int position) {
        return ClothingCategoryFragment.newInstance(mCategories[position]);
    }

    @Override
    public int getCount() {
        return mCategories.length;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        Log.d("getPageTitle", mCategories[position]);
        return mCategories[position];
    }
}

在我的活动中,我实现了这个类.

ClothingSectionsPagerAdapter sectionsPagerAdapter =
                new ClothingSectionsPagerAdapter(getSupportFragmentManager());

sectionsPagerAdapter.setContext(this);
mViewPager.setAdapter(sectionsPagerAdapter);
mViewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(mTabLayout));
mTabLayout.addOnTabSelectedListener(new TabLayout.ViewPagerOnTabSelectedListener(mViewPager));
mViewPager.setCurrentItem(startingFragmentPosition);

但是当我运行我的应用程序时.标签存在,但它们是无标题.getPageTitle永远不会调用该方法.我该如何解决？

我有一个小时的使用RxJava的经验,我试图在我的项目中实现它,而不是使用接口和监听器.

我有一个异步任务,它在一个单独的模块中调用谷歌云端点方法,并List<Profile>在完成时收到.

在onPostExecute()异步任务的方法中,我调用onNext以便任何订阅者都能接收到这些数据.

这是AsyncTask看起来像:

private BirthpayApi mApi;
private String mUserId;
private ReplaySubject<List<Profile>> notifier = ReplaySubject.create();

public GetFriends(String userId) {
    mUserId = userId;
}

public Observable<List<Profile>> asObservable() {
    return notifier;
}

@Override
protected List<Profile> doInBackground(Void... params) {
    if (mApi == null) {
        BirthpayApi.Builder builder = new BirthpayApi.Builder(AndroidHttp.newCompatibleTransport(),
                    new AndroidJsonFactory(), null)
                    // options for running against local devappserver
                    // - 10.0.2.2 is localhost's IP address in Android emulator
                    // - turn off compression when running against …

我在我的android项目中使用Butterknife.我之前使用过这个,但由于某种原因它不再适用于新的更新.

这是我的设置:

(App Module)build.gradle:

compile 'com.jakewharton:butterknife:8.4.0'

活动:

@BindView(R.id.navigation_pager) ViewPager mViewPager;

/.../

@Override
protected void onCreate(Bundle savedInstanceState) {
    /...
    /...
    ButterKnife.bind(this);

堆栈跟踪:

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.view.ViewPager.setAdapter(android.support.v4.view.PagerAdapter)' on a null object reference

为了Butterknife上班,我错过了什么？

谢谢.