Question

public static List<Integer> listResWithFilter(String startingCharacter, boolean 
shouldFetchRaw, boolean shouldFetchDrawable) throws IllegalAccessException {
    List<Integer> listofraw = new ArrayList<>();

    if(shouldFetchRaw){
        Field[] fields=R.raw.class.getFields();
        Log.i(TAG, "listResWithFilter: raw length: " + fields.length);
        for (int i = 0; i <= fields.length; i++) {
            Field field = fields[i];
            if(field.getName().startsWith(startingCharacter)){
                int id = fields[i].getInt(fields[i]);
                listofraw.add(id);
            }
        }
    }
    if(shouldFetchDrawable){
        Field[] fields=R.drawable.class.getFields();
        Log.i(TAG, "listResWithFilter: drawable length: " + fields.length);
        for (int i = 0; i < fields.length; i++) {
            Field field = fields[i];
            Log.i(TAG, "listResWithFilter: checking: "+field.getName());
            if(field.getName().startsWith(startingCharacter) && field.getName().length() < 5){
                //listofraw[index] = fields[i].getInt(fields[i]);
                int id = fields[i].getInt(fields[i]);
                listofraw.add(id);
                Log.i(TAG, "listResWithFilter: found match: "+field.getName()+" id: "+id);
            }
        }
        Log.i(TAG, "listResWithFilter: found matches: "+listofraw.size());
    }


    return listofraw;
}

java.lang.RuntimeException：无法启动活动ComponentInfo {net.zahrauniversity.madaniqaida / net.zahrauniversity.madaniqaida.lesson.DynamicLesson}：java.lang.NullPointerException：尝试从字段'int java.lang.String中读取.count”在空对象引用上在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2594）在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2685）在android.app.ActivityThread.access $ 900（ActivityThread.java:188）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1530）在android.os.Handler.dispatchMessage（Handler.java:111）在android.os.Looper.loop（Looper.java:210）在android.app.ActivityThread.main（ActivityThread.java:5839）在java.lang.reflect.Method.invoke（本机方法）在java.lang.reflect.Method.invoke（Method.java:372）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:1113）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:879）原因：java.lang.NullPointerException：尝试从空对象引用上的字段'int java.lang.String.count'中读取在java.lang.String.startsWith（String.java:1200）在java.lang.String.startsWith（String.java:1183）在net.zahrauniversity.madaniqaida.Helper.LessonLayoutHelper.listResWithFilter（LessonLayoutHelper.java:142）在net.zahrauniversity.madaniqaida.lesson.DynamicLesson.onCreate（DynamicLesson.java:129）在android.app.Activity.performCreate（Activity.java:6177）在android.app.Instrumentation.callActivityOnCreate（Instrumentation.java:1112）在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2541）在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2685）在android.app.ActivityThread.access $ 900（ActivityThread.java:188）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1530）在android.os.Handler.dispatchMessage（Handler.java:111）在android.os.Looper.loop（Looper.java:210）在android.app.ActivityThread.main（ActivityThread.java:5839）在java.lang.reflect.Method.invoke（本机方法）在java.lang.reflect.Method.invoke（Method.java:372）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:1113）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:879）

尝试从空对象引用

0 个答案: