Question

我有一个方法，我从twitter API加载特定id的关注者，我在课堂上使用它两次，一个加载logged in user's followers，一个加载other user's followers。登录用户的关注者工作正常，代码类似于下面，只是不同的ID。以下代码用于加载followers for other users。我想是在方法中没有调用onResponse，因此otherFollowers为空。我能知道为什么吗？

public interface ServiceListeners2 {
//For getting friends :  @GET("1.1/friends/list.json")
@GET("1.1/followers/list.json")
Call<FollowersResponseModel> list(@Query("user_id") long id);
}

栈跟踪

E/AndroidRuntime: FATAL EXCEPTION: main
              Process: chuan.twittertwitterlittlestar, PID: 9957
              java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.List.size()' on a null object reference
                  at chuan.twittertwitterlittlestar.FollowerFragment.loadOtherFollowers(FollowerFragment.java:256)
                  at chuan.twittertwitterlittlestar.FollowerFragment.access$100(FollowerFragment.java:50)
                  at chuan.twittertwitterlittlestar.FollowerFragment$3.onItemClick(FollowerFragment.java:175)
                  at android.widget.AdapterView.performItemClick(AdapterView.java:318)
                  at android.widget.AbsListView.performItemClick(AbsListView.java:1165)
                  at android.widget.AbsListView$PerformClick.run(AbsListView.java:3134)
                  at android.widget.AbsListView$3.run(AbsListView.java:4049)
                  at android.os.Handler.handleCallback(Handler.java:789)
                  at android.os.Handler.dispatchMessage(Handler.java:98)
                  at android.os.Looper.loop(Looper.java:164)
                  at android.app.ActivityThread.main(ActivityThread.java:6541)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
Application terminated.

在onCreateView中，

    mainListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {

        public void onItemClick(AdapterView<?> parent, View view,
                                int position, long id) {

            if (twitterFollowers.get(position).getId() != 0){
                follower_num = loadOtherFollowers(twitterFollowers.get(position).getId());
                MyCustomAlertDialog(twitterFollowers.get(position).getProfilePictureUrl(), follower_num);
                Toast.makeText(getActivity(), twitterFollowers.get(position).getScreenName(),Toast.LENGTH_LONG).show();
                //sendMsg(twitterFriends.get(position).getId(),twitterFriends.get(position).getScreenName(),"");
            }

        }

    });

Answer 1

好的就是这件事。您正在尝试调用同步方法来返回在完成网络调用Twitter API时将创建的内容。但是在完成并获取结果之前，列表为空，因此应用程序将始终崩溃。这是你能做的。

创建一个侦听器接口，该接口将充当API中的数据与列表中的用法之间的桥梁，如下所示：

build job: 'debug/job2', parameters: [[$class: 'StringParameterValue', name: 'PARAM', value: env.VERSION]], wait: false

并在此之后修改此方法，如下所示：

interface MyListener {
  void onFollowersReceived(int listSize);
}

然后在你的列表中它将是这样的：

private void loadOtherFollowers(long id, MyListener listener) {
    Log.e("ID","id is "+id);
    MyTwitterApiClient myTwitterApiClient2 = new MyTwitterApiClient(twitterSession);
    myTwitterApiClient2.getCustomTwitterService2().list(id).enqueue(new retrofit2.Callback<FollowersResponseModel>() {
        @Override
        public void onResponse(Call<FollowersResponseModel> call, Response<FollowersResponseModel> response) {
            Log.e("onResponse",response.toString());
            otherFollowers = fetchResults2(response);
            Log.e("onResponse","otherFollowers:" +otherFollowers.size());
            listener.onFollowersReceived(otherFollowers.size());
        }

        @Override
        public void onFailure(Call<FollowersResponseModel> call, Throwable t) {
            Log.e("onFailure",t.toString());
            listener.onFollowersReceived(0);// here you can also put -1 and handle it as error
        }
    });
}

希望它有所帮助!!

Answer 2

试试这个：

    mainListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {

            public void onItemClick(AdapterView<?> parent, View view,
                                    int position, long id) {

                if (twitterFollowers.get(position).getId() != 0){
                    loadOtherFollowers(twitterFollowers.get(position).getId());

                }

            }

        });




private void loadOtherFollowers(long id) {
    Log.e("ID","id is "+id);
    MyTwitterApiClient myTwitterApiClient2 = new MyTwitterApiClient(twitterSession);
    myTwitterApiClient2.getCustomTwitterService2().list(id).enqueue(new retrofit2.Callback<FollowersResponseModel>() {
        @Override
        public void onResponse(Call<FollowersResponseModel> call, Response<FollowersResponseModel> response) {
            Log.e("onResponse",response.toString());
            otherFollowers = fetchResults2(response);
            Log.e("onResponse","otherFollowers:" +otherFollowers.size());
                    MyCustomAlertDialog(twitterFollowers.get(position).getProfilePictureUrl(), otherFollowers.size());
                    Toast.makeText(getActivity(), twitterFollowers.get(position).getScreenName(),Toast.LENGTH_LONG).show();
                    //sendMsg(twitterFriends.get(position).getId(),twitterFriends.get(position).getScreenName(),"");
        }

        @Override
        public void onFailure(Call<FollowersResponseModel> call, Throwable t) {
            Log.e("onFailure",t.toString());
        }

    });


}

没有调用Retrofit2 onResponse

2 个答案: