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问JSON API解析问题
EN

Stack Overflow用户

提问于 2018-08-24 06:10:19

回答 2查看 133关注 0票数 0

我创建了一个GUI，其中列出了Hydra电影数据库API中列出的评分最高和评分最低的电影。当我使用Compare.Comparing和parseInt解析它来查找最大和最小IMDB评级时，我得到了一个数字格式异常。我将最大值改为parseDouble，只是为了看看这是否有帮助，我得到了一个空指针异常。

我把具体相关的代码和错误放在这里，但如果你想了解更全面的情况，这里有GitHub：https://github.com/scohen40/cohen-mcw152-MovieDatabaseJSON/tree/bugFixing/src/movieDatabaseApp/movie上该项目的链接

下面是我的控制器的代码：

package movieDatabaseApp.movie;

import java.awt.event.ActionEvent;
import java.util.Comparator;
import java.util.List;
import java.util.Optional;

import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;

import javax.swing.text.JTextComponent;

import com.google.inject.Inject;

public class MovieController {


    private MovieView view;
    private MovieService service;

    @Inject
    public
    MovieController(MovieView view, MovieService service) {
        this.view = view;
        this.service = service;
    }

    public void refreshData() {
        requestHighest2018();
        requestLowest2018();
    }

    public void requestHighest2018() {
        requestHighestMovies(service.getAllMovies(),
//      requestHighestMovies(service.getMovies2018(),
                view.gethTitleField(),
                view.gethYearField(),
                view.gethRatingField(),
                view.gethLanguageField());          
    }
    void requestLowest2018() {
        requestLowestMovies(service.getAllMovies(),
//      requestLowestMovies(service.getMovies2018(),
                view.getlTitleField(),
                view.getlYearField(),
                view.getlRatingField(),
                view.getlLanguageField());          
    }




    private void requestHighestMovies(Call<List<Movie>> call,
        JTextComponent title,
        JTextComponent year,
        JTextComponent rating,
        JTextComponent language) 
    {
        call.enqueue(new Callback<List<Movie>>() {
            @Override
            public void onResponse(Call<List<Movie>> call, Response<List<Movie>> response) {
                List<Movie> list = response.body();

                showHighest(list, title, year, rating, language);

            }

            @Override
            public void onFailure(Call<List<Movie>> arg0, Throwable t) {
                t.printStackTrace();
            }

        });

    }

    private void requestLowestMovies(Call<List<Movie>> call,
            JTextComponent title,
            JTextComponent year,
            JTextComponent rating,
            JTextComponent language) 
        {
            call.enqueue(new Callback<List<Movie>>() {
                @Override
                public void onResponse(Call<List<Movie>> call, Response<List<Movie>> response) {
                    List<Movie> list = response.body();

                    showLowest(list, title, year, rating, language);

                }

                @Override
                public void onFailure(Call<List<Movie>> arg0, Throwable t) {
                    t.printStackTrace();
                }

            });

        }

    public void showHighest(List<Movie> list,
            JTextComponent title,
            JTextComponent year,
            JTextComponent rating,
            JTextComponent language) 
    {
        Optional<Movie> highest = list.stream()
                .max(Comparator.comparingDouble(e -> Double.parseDouble(e.getImdb_rating())));

        title.setText(String.valueOf(highest.get().getTitle()));
        year.setText(String.valueOf(highest.get().getMovie_year()));
        rating.setText(String.valueOf(highest.get().getImdb_rating()));
        language.setText(String.valueOf(highest.get().getLanguage()));
    }

    void showLowest(List<Movie> list,
            JTextComponent title,
            JTextComponent year,
            JTextComponent rating,
            JTextComponent language) 
    {
        Optional<Movie> lowest = list.stream()
                .min(Comparator.comparing(e -> Integer.parseInt(e.getImdb_rating())));

        title.setText(String.valueOf(lowest.get().getTitle()));
        year.setText(String.valueOf(lowest.get().getMovie_year()));
        rating.setText(String.valueOf(lowest.get().getImdb_rating()));
        language.setText(String.valueOf(lowest.get().getMovie_year()));
    }

}

这是我得到的错误，最大值解析为双精度，最小值为整型：

java.lang.NullPointerException

at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1838)

at sun.misc.FloatingDecimal.parseDouble(FloatingDecimal.java:110)

at java.lang.Double.parseDouble(Double.java:538)

at movieDatabaseApp.movie.MovieController.lambda$0(MovieController.java:109)

at java.util.Comparator.lambda$comparingDouble$8dcf42ea$1(Comparator.java:532)

at java.util.function.BinaryOperator.lambda$maxBy$1(BinaryOperator.java:74)

at java.util.stream.ReduceOps$2ReducingSink.accept(ReduceOps.java:123)

at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1380)

at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)

at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)

at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)

at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)

at java.util.stream.ReferencePipeline.reduce(ReferencePipeline.java:479)

at java.util.stream.ReferencePipeline.max(ReferencePipeline.java:515)

at movieDatabaseApp.movie.MovieController.showHighest(MovieController.java:109)

at movieDatabaseApp.movie.MovieController$1.onResponse(MovieController.java:65)

at retrofit2.OkHttpCall$1.onResponse(OkHttpCall.java:123)

at okhttp3.RealCall$AsyncCall.execute(RealCall.java:153)

at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32)

at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)

at java.lang.Thread.run(Thread.java:748)

java.lang.NumberFormatException:输入字符串："7.4“

at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)

at java.lang.Integer.parseInt(Integer.java:580)

at java.lang.Integer.parseInt(Integer.java:615)

at movieDatabaseApp.movie.MovieController.lambda$1(MovieController.java:124)

at java.util.Comparator.lambda$comparing$77a9974f$1(Comparator.java:469)

at java.util.function.BinaryOperator.lambda$minBy$0(BinaryOperator.java:59)

at java.util.stream.ReduceOps$2ReducingSink.accept(ReduceOps.java:123)

at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1380)

at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)

at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)

at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)

at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)

at java.util.stream.ReferencePipeline.reduce(ReferencePipeline.java:479)

at java.util.stream.ReferencePipeline.min(ReferencePipeline.java:520)

at movieDatabaseApp.movie.MovieController.showLowest(MovieController.java:124)

at movieDatabaseApp.movie.MovieController$2.onResponse(MovieController.java:89)

at retrofit2.OkHttpCall$1.onResponse(OkHttpCall.java:123)

at okhttp3.RealCall$AsyncCall.execute(RealCall.java:153)

at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32)

at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)

at java.lang.Thread.run(Thread.java:748)

我是JSON API集成的新手，所以我真的不知道这个主题上的错误意味着什么，也不知道什么是正常的。任何帮助都将不胜感激。

另外-如果您想看一下，这里是正在解析的原始JSON：https://hydramovies.com/api-v2/?source=http://hydramovies.com/api-v2/current-Movie-Data.csv

java

json

api

retrofit

jsonparser

回答 2

Stack Overflow用户

回答已采纳

发布于 2018-08-25 02:47:10

更新:我最终将imdb_ratings的数据类型从字符串转换为双精度，并去掉了过滤器和解析器。现在它起作用了！

你可以在上面列出的我的GitHub上查看它。

票数 0

Stack Overflow用户

发布于 2018-08-24 06:14:11

我不认为这个错误与JSON本身有任何关系。你得到NPE或NFE是因为你的列表中有一部或多部电影没有IMDB评级，或者评级中有小数，这不能是整数可解析的，

票数 0

页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://stackoverflow.com/questions/51994950

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