阵列中的“后退”按钮导致应用崩溃

Question

因此我正在电影评论应用上进行学校项目。所以这是我的下一个和上一个按钮的代码。下一个按钮可以正常工作而不会崩溃。当我按回它时，它可以工作，但是一旦它到达了第一部电影，我又回按了该应用程序便崩溃了。

void OnCollisionEnter2D(Collision2D col){
    FixedJoint2D myjoint = gameObject.AddComponent<FixedJoint2D>();
    myjoint.connectedBody = col.rigidbody;
}

我的按钮代码。

private Movie movies[]= new Movie[5];

public MovieCollection(){
    prepareMovies();
}

public Movie searchById(String id){
    Movie movie = null;

    for(int index=0; index < movies.length; index++){
        movie = movies[index];
        if(movie.getId().equals(id)){
            return movie;
        }
    }
    return movie;
}
public Movie getNextMovie(String currentMovieId){
    Movie movie = null;
    for(int index = 0; index < movies.length; index++) {
        String tempMovieId = movies[index].getId();
        if (tempMovieId.equals(currentMovieId) && (index < movies.length - 1)) {
            movie = movies[index + 1];
            break;
        }
    }
    return movie;
}


public Movie getPrevMovie(String currentMovieId){
    Movie movie = null;
    for(int index = 0; index < movies.length; index++){
        String tempMovieId = movies[index].getId();
        if(tempMovieId.equals(currentMovieId) && (index > 0)){
            movie = movies[index - 1];
            break;
        }
    }
    return movie;
}

错误报告谁可以告诉我我的代码出了什么问题。谢谢

public void goNext(View view){
    Movie nextMovie = movieCollection.getNextMovie(movieId);
    if(nextMovie != null){
        movieId = nextMovie.getId();
        title = nextMovie.getTitle();
        plot = nextMovie.getPlot();
        movieArt = nextMovie.getMovieArt();
        rating = nextMovie.getRating();
        review1 = nextMovie.getReview1();
        review2 = nextMovie.getReview2();
        displayMovie(title , plot, movieArt, rating, review1, review2);
    }
}
public void goPrevious(View view){
    Movie prevMovie = movieCollection.getPrevMovie(movieId);
    if (prevMovie != null){
        movieId = prevMovie.getId();
        title = prevMovie.getTitle();
        plot = prevMovie.getPlot();
        movieArt = prevMovie.getMovieArt();
        rating = prevMovie.getRating();
        review1 = prevMovie.getReview1();
        review2 = prevMovie.getReview2();
        displayMovie(title , plot, movieArt, rating, review1, review2);

    }
}