无法启动活动 ComponentInfo{project} java.lang.IndexOutOfBoundsExce

Question

我从主要活动MoviesService和LiveMovieServices调用UpdateUI时遇到此错误。我正在尝试制作电影应用程序

错误：

05-07 15:30:07.956 3694-3694/com.youssefz.beastmovies.live E/AndroidRuntime: FATAL EXCEPTION: main
   Process: com.youssefz.beastmovies.live, PID: 3694
   java.lang.RuntimeException: Unable to start activity ComponentInfo{com.youssefz.beastmovies.live/com.example.youssefz.beastmovies.activities.MainActivity}: java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
       at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2665)
       at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
       at android.app.ActivityThread.-wrap12(ActivityThread.java)
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
       at android.os.Handler.dispatchMessage(Handler.java:102)
       at android.os.Looper.loop(Looper.java:154)
       at android.app.ActivityThread.main(ActivityThread.java:6119)
       at java.lang.reflect.Method.invoke(Native Method)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
    Caused by: java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
       at java.util.ArrayList.get(ArrayList.java:411)
       at com.example.youssefz.beastmovies.activities.MainActivity.onCreate(MainActivity.java:55)
       at android.app.Activity.performCreate(Activity.java:6679)
       at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
       at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2618)
       at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726) 
       at android.app.ActivityThread.-wrap12(ActivityThread.java) 
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477) 
       at android.os.Handler.dispatchMessage(Handler.java:102) 
       at android.os.Looper.loop(Looper.java:154) 
       at android.app.ActivityThread.main(ActivityThread.java:6119) 

主要活动

public class MainActivity extends BaseActivity {

@BindView(R.id.activity_main_progressBar)
ProgressBar progressBar;
@BindView(R.id.activity_main_movie_summary)
TextView movieSummary;
@BindView(R.id.activity_main_movieTitle)
TextView movieTitle;
@BindView(R.id.activity_main_movie_vote)
TextView movieVote;
@BindView(R.id.activity_main_moviePicture)
ImageView moviePicture;
@BindView(R.id.activity_main_movieReleaseDate)
TextView movieReleaseDate;
@BindView(R.id.activity_main_left_arrow)
ImageView leftArrow;
@BindView(R.id.activity_main_right_arrow)
ImageView rightArrow;
ArrayList<Movie> movies;
int index;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ButterKnife.bind(this);
movies = new ArrayList<>();
index=0;
bus.post(new MovieServices.SearchMoviesRequest("query"));
UpdateUI(movies.get(0));
}
private void UpdateUI(Movie movie) {
progressBar.setVisibility(View.VISIBLE);
movieTitle.setText(movie.getMovieTitle());
movieSummary.setText(movie.getMovieSummary());
movieReleaseDate.setText(movie.getMovieSummary());
movieVote.setText(Double.toString(movie.getMovieRating()));
Log.i(MainActivity.class.getSimpleName(),movie.getMoviePicture());
Picasso.with(this).load(movie.getMoviePicture())
.fit()
.centerCrop()
.into(moviePicture, new Callback() {
@Override
public void onSuccess() {
progressBar.setVisibility(View.GONE);
}
@Override
public void onError() {
}
});

}


@OnClick(R.id.activity_main_left_arrow)
public void setUpLeftArrow() {

if(index == 0){
Toast.makeText(this,"This is the start of the movies!",Toast.LENGTH_LONG).show();
}else{
index --;
UpdateUI(movies.get(index));
}
}
@OnClick(R.id.activity_main_right_arrow)
public void setUpRightArrow() {
if(index == movies.size()-1){
Toast.makeText(this,"This is the end of the movies!",Toast.LENGTH_LONG).show();
}else{
index ++;
UpdateUI(movies.get(index));
}
}

@Subscribe
public void getMovieMessage(MovieServices.SearchMoviesResponse response) {
movies.clear();
movies = response.movies;
}

}

电影服务

public class MovieServices {
private MovieServices(){
}
public static class SearchMoviesRequest{
public String query;
public SearchMoviesRequest (String query){
this.query = query;
}
}
public static class SearchMoviesResponse{
public ArrayList<Movie> movies;
}

}

现场电影服务：

public class LiveMovieService extends BaseLiveServices {
public LiveMovieService(BeastMoviesApplication application) {
super(application);
}
@Subscribe
public void getMovieMessage(MovieServices.SearchMoviesRequest request){
MovieServices.SearchMoviesResponse response = new MovieServices.SearchMoviesResponse();
response.movies = new ArrayList<>();
for(int i=0;i<4;i++){
Movie movie = new Movie ("Joe's android movie" + i+ "!", "The is a movie where Joe has Android Dreams" + i, BeastMoviesApplication.BESE_PICTURE_URL+"/wSJPjqp2AZWQ6REaqkMuXsCIs64.jpg","10/3/2016",5.0);
response.movies.add(movie);
}
bus.post(response);
}

}

Answer 1

movies = new ArrayList<>();

在这里，您将一个空ArrayList分配给movies。

然后，三个 Java 语句之后，您调用movies.get(0)。由于movies为空，因此无法get()对象movies。

Answer 2

您正在尝试获取空ArrayList的第一项，而无需等待来自 Web 服务的响应。

您应该等待来自 Web 服务的响应填充您的 ArrayList。之后，您可以调用此方法(如果列表不为空)。

UpdateUI(movies.get(0));

Answer 3

movies是空的，所以你不能使用movies.get(0)