Question

我在这里，因为我无法弄清楚为什么我得到一个没有正当理由的nullPointerException，我也尝试使用catch块来帮助我解决问题，但是消息为null并且printStackTrace为（void），这个问题出现在一个数组循环中，在第一个项目中它的一切都很好但在第二个项目中它会抛出NullPointerExcption。

09-16 14:45:09.053: E/AndroidRuntime(4332): FATAL EXCEPTION: main 
09-16 14:45:09.053: E/AndroidRuntime(4332): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.moody/activities.MainActivity}: java.lang.NullPointerException 09-16 14:45:09.053: E/AndroidRuntime(4332): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956) 
09-16 14:45:09.053: E/AndroidRuntime(4332): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981) 
09-16 14:45:09.053: E/AndroidRuntime(4332): at android.app.ActivityThread.access$600(ActivityThread.java:123) 09-16 14:45:09.053: E/AndroidRuntime(4332): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147) 
09-16 14:45:09.053: E/AndroidRuntime(4332): at android.os.Handler.dispatchMessage(Handler.java:99) 
09-16 14:45:09.053: E/AndroidRuntime(4332): at android.os.Looper.loop(Looper.java:137) 09-16 14:45:09.053: E/AndroidRuntime(4332): at android.app.ActivityThread.main(ActivityThread.java:4424) 
09-16 14:45:09.053: E/AndroidRuntime(4332): at java.lang.reflect.Method.invokeNative(Native Method) 
09-16 14:45:09.053: E/AndroidRuntime(4332): at java.lang.reflect.Method.invoke(Method.java:511) 
09-16 14:45:09.053: E/AndroidRuntime(4332): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 
09-16 14:45:09.053: E/AndroidRuntime(4332): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 
09-16 14:45:09.053: E/AndroidRuntime(4332): at dalvik.system.NativeStart.main(Native Method) 
09-16 14:45:09.053: E/AndroidRuntime(4332): Caused by: java.lang.NullPointerException 
09-16 14:45:09.053: E/AndroidRuntime(4332): at fragments.TopicsPreview.createTopicsContent(TopicsPreview.java:162) 
09-16 14:45:09.053: E/AndroidRuntime(4332): at fragments.TopicsPreview.createTopicsRows(TopicsPreview.java:85) 
09-16 14:45:09.053: E/AndroidRuntime(4332): at fragments.TopicsPreview.onCreateView(TopicsPreview.java:59) 
09-16 14:45:09.053: E/AndroidRuntime(4332): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:828) 
09-16 14:45:09.053: E/AndroidRuntime(4332): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1032) 
09-16 14:45:09.053: E/AndroidRuntime(4332): at android.app.BackStackRecord.run(BackStackRecord.java:622) 
09-16 14:45:09.053: E/AndroidRuntime(4332): at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1382) 
09-16 14:45:09.053: E/AndroidRuntime(4332): at android.app.Activity.performStart(Activity.java:4474) 
09-16 14:45:09.053: E/AndroidRuntime(4332): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1929) 
09-16 14:45:09.053: E/AndroidRuntime(4332): ... 11 more

Debug Expressions

protected void createTopicsContent(MoodleCourseContent[] courseContent,
        LayoutInflater inflater, LinearLayout insertPoint, String courseId) {

    for (int j = 0; j < courseContent.length; j++) {

        final LinearLayout row = new LinearLayout(getActivity());
        row.setLayoutParams(new LayoutParams(
                android.view.ViewGroup.LayoutParams.MATCH_PARENT,
                android.view.ViewGroup.LayoutParams.WRAP_CONTENT));
        View topicsView = inflater.inflate(R.layout.topics_preview_context,
                null);
        TextView topicName = (TextView) topicsView
                .findViewById(R.id.topic_label);

        topicName.setText(courseContent[j].getName());

        // Loop for the modules array
        MoodleModule[] modules = courseContent[j].getMoodleModules();

        for (int i = 0; i < modules.length; i++) {

            final TextView topicModule = (TextView) topicsView
                    .findViewById(R.id.content_preview_textView);
            if (!modules[i].getName().isEmpty()) {

                try {
                    topicModule.setText(modules[i].getName());
                } catch (NullPointerException e) {

                    e.printStackTrace();
                    e.getMessage();
                }

            }

            // Where the textview id will be course id and the textview
            // tag will be the topic id
            topicModule.setId(Integer.parseInt(courseId));
            topicModule.setTag(Long.toString(modules[i].getId()));

            row.addView(topicsView);
            insertPoint.addView(row);

        }
    }

}

Answer 1

尝试在onCreate方法之外运行此代码。日志显示“无法启动活动”当onCreate方法中的某些内容抛出异常时会发生这种情况。这也可能是此代码失败的原因，textviews尚未初始化。

尝试在onResume方法中运行此代码。

Answer 2

它解决了几个结构问题，因为我这样做而没有检查空数组和其他几个错误，这是我们匆忙时开发的结果。谢谢所有花费的时间;）PS：管理员可以删除这个，这个问题对任何人都没有帮助

NullPointerException textView.setText（）

2 个答案: