java - 从Java更改为Android的空指针异常

Question

我们制作了一个 Java 应用程序并将其转换为 Android。我们需要读取一个名为“en-sent.bin”的bin文件，但在Android中存在空指针异常。我已将 bin 文件放入项目的 asset 文件夹中，并与 AssetManagers 混淆，但没有任何效果。 ModelIn 和模型变量始终为 null，这使得句子检测器返回空指针异常。我正在使用需要此 bin 文件才能工作的 Apache 句子检测器库。

这是我们的原始代码(来自 Java 应用程序):

    SentenceModel model = null;
    InputStream modelIn = null;
    try {
        modelIn = new FileInputStream("en-sent.bin");
        model = new SentenceModel(modelIn);
    }
    catch (IOException e) {
        e.printStackTrace();
    }
    finally {
        if (modelIn != null) {
            try {
                modelIn.close();
            }
            catch (IOException e) {
            }
        }
    }

    //initializes sentence detector
    SentenceDetectorME sentenceDetector = new SentenceDetectorME(model);
    String[] sentencesTemp = sentenceDetector.sentDetect(article);

堆栈跟踪:

08-04 10:11:09.755 10247-10247/com.gigstudios.newssummary W/System.err: java.io.FileNotFoundException: en-sent.bin: open failed: ENOENT (No such file or directory)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err:     at libcore.io.IoBridge.open(IoBridge.java:452)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err:     at java.io.FileInputStream.<init>(FileInputStream.java:76)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err:     at java.io.FileInputStream.<init>(FileInputStream.java:103)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err:     at com.gigstudios.newssummary.WordCounter.makeSentences(WordCounter.java:52)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err:     at com.gigstudios.newssummary.Article.<init>(Article.java:19)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err:     at com.gigstudios.newssummary.ArticleReceiver.receiveNewsArticles(ArticleReceiver.java:87)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err:     at com.gigstudios.newssummary.ArticleReceiver.<init>(ArticleReceiver.java:37)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err:     at com.gigstudios.newssummary.MainActivity.fetchNews(MainActivity.java:114)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err:     at com.gigstudios.newssummary.MainActivity$1.run(MainActivity.java:52)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err:     at android.os.Handler.handleCallback(Handler.java:746)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:95)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err:     at android.os.Looper.loop(Looper.java:148)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:5443)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err: Caused by: android.system.ErrnoException: open failed: ENOENT (No such file or directory)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err:     at libcore.io.Posix.open(Native Method)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err:     at libcore.io.BlockGuardOs.open(BlockGuardOs.java:186)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err:     at libcore.io.IoBridge.open(IoBridge.java:438)
08-04 10:11:09.756 10247-10247/com.gigstudios.newssummary W/System.err:     ... 15 more
08-04 10:11:09.757 10247-10247/com.gigstudios.newssummary D/AndroidRuntime: Shutting down VM
08-04 10:11:09.757 10247-10247/com.gigstudios.newssummary E/AndroidRuntime: FATAL EXCEPTION: main
                                                                            Process: com.gigstudios.newssummary, PID: 10247
                                                                            java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String[] opennlp.tools.sentdetect.SentenceDetectorME.sentDetect(java.lang.String)' on a null object reference
                                                                                at com.gigstudios.newssummary.WordCounter.makeSentences(WordCounter.java:56)
                                                                                at com.gigstudios.newssummary.Article.<init>(Article.java:19)
                                                                                at com.gigstudios.newssummary.ArticleReceiver.receiveNewsArticles(ArticleReceiver.java:87)
                                                                                at com.gigstudios.newssummary.ArticleReceiver.<init>(ArticleReceiver.java:37)
                                                                                at com.gigstudios.newssummary.MainActivity.fetchNews(MainActivity.java:114)
                                                                                at com.gigstudios.newssummary.MainActivity$1.run(MainActivity.java:52)
                                                                                at android.os.Handler.handleCallback(Handler.java:746)
                                                                                at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                                at android.os.Looper.loop(Looper.java:148)
                                                                                at android.app.ActivityThread.main(ActivityThread.java:5443)
                                                                                at java.lang.reflect.Method.invoke(Native Method)
                                                                                at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728)
                                                                                at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)

Answer 1

您应该在 /res/raw/en_sent.bin 中有 en-sent.bin (请注意，您必须将破折号更改为下划线。)然后替换

        modelIn = new FileInputStream("en-sent.bin");

与

        modelIn = getResources().openRawResource(R.raw.en_sent);

这是假设您从Activity调用。如果您从 fragment 调用，则需要首先获取 Context，即 getActivity().getResources()...