Java for循环只存储最后一个值

Question

我在 java android 中有一个 for 循环，它运行完美，但它只存储到它循环遍历的列表中的最后一项。我应该将 user_id 和 lesson_id 设为列表吗？我不知道从这里该去哪里，但这就是我所做的。该逻辑工作正常，但它只保存两个变量中列表中的一项。

Android Studio 代码:

// loop to add every user and lesson selected to watch
String user_id = null;
int lesson_id = 0;

for (int i = 0; i<attendees.size(); i++){
    for (int j = 0; j<lesson_iDs.size(); j++){
         user_id = attendees.get(i);
         lesson_id = lesson_iDs.get(j);
    }
}
// get the date for the classWatch
Calendar localCalendar = Calendar.getInstance(TimeZone.getDefault());
Date currentTime = localCalendar.getTime();

// to show in patient activity (sends to SQLite)
watch = new Watch(currentTime, user_id, lesson_id);

Answer 1

这正常吗？如果您在循环之外使用 user_id 和 Lesson_id，则使用最后的值。难道你不想做这样的事情:

// loop to add every user and lesson selected to watch
String user_id = null;
int lesson_id = 0;
// get the date for the classWatch
Calendar localCalendar = Calendar.getInstance(TimeZone.getDefault());
Date currentTime = localCalendar.getTime();

for (int i = 0; i<attendees.size(); i++){
    for (int j = 0; j<lesson_iDs.size(); j++){
         user_id = attendees.get(i);
         lesson_id = lesson_iDs.get(j);
         // to show in patient activity (sends to SQLite)
         watch = new Watch(currentTime, user_id, lesson_id);
         // Do something with watch...
    }
}