android - 将系统日期和时间与数据库日期和时间分开比较，以开始另一项 Activity

Question

这可能是我在 StackOverFlow 中找到的类似问题。但是我的情况与所有人都有点不同。在我的数据库中，我有开始日期和开始时间。我希望系统分别比较它的日期和时间，因为开始日期和时间在数据库中的不同列中。首先，系统比较日期，然后比较时间。仅当日期相同且时间早于数据库中的开始时间 15 分钟时，才应打开另一个 Activity 。到目前为止，我已经这样做了；

private void startTraining() {
    Calendar calendar1 = Calendar.getInstance();
    SimpleDateFormat formatter = new SimpleDateFormat("MM-dd-yyy");

    String currentDate = formatter.format(calendar1.getTime());
    System.out.println(currentDate);

    Calendar calendar2 = Calendar.getInstance();
    SimpleDateFormat formatter2 = new SimpleDateFormat("hh:mm");

    String currentTime = formatter2.format(calendar2.getTime());
    System.out.println(currentTime);

    String trainingStartDate = SharedMemory.getInstance()
            .getCurrentTraining().getDate();

    String trainingStartTime = SharedMemory.getInstance()
            .getCurrentTraining().getStartTime();
    int difference = trainingStartTime.compareTo(currentTime);

    System.out.println(difference);
    //System.out.println(trainingStartTime);


    if (currentDate.toString().equals(trainingStartDate)&& difference < 15) {

        Log.i("Debug", "CHECKPOINT");
        Intent intent = new Intent(getApplicationContext(),
                TraineeListActivity.class);
        MainActivity.this.startActivity(intent);

        finish();
    } else{

    }

}

我没有得到我期望的结果。提前致谢。

Answer 1

您使用 String.compareTo() 来比较“时间”String，这将无法正常工作。尝试将代码更改为此

private void startTraining() throws ParseException {
    // current date & time
    Calendar now = Calendar.getInstance();

    // parse date & time from database
    String trainingStartDate = SharedMemory.getInstance()
        .getCurrentTraining().getDate();
    String trainingStartTime = SharedMemory.getInstance()
        .getCurrentTraining().getStartTime();
    String strDateTime = trainingStartDate + " " + trainingStartTime;

    Calendar training = Calendar.getInstance();
    training.setTime(new SimpleDateFormat("MM-dd-yyyy kk:mm")
        .parse(strDateTime));

    // find difference in milliseconds
    long difference = training.getTimeInMillis() - now.getTimeInMillis();

    if (difference < 15 * 60 * 1000) { //less than 15 minutes
        Log.i("Debug", "CHECKPOINT");
        Intent intent = new Intent(getApplicationContext(),
            TraineeListActivity.class);
        MainActivity.this.startActivity(intent);

        finish();
    } else {

    }
}