在Java中无法从String转换为int

Question

I'm getting the current time and I want to convert it into Integer, thats what I did , but it keeps giving me java.lang.NumberFormatException: For input string: "4:12:31"

            long unixTime = System.currentTimeMillis() / 1000L;
            Date time=new java.util.Date((long)unixTime*1000);
            Calendar cal = Calendar.getInstance();
            cal.setTime(time);
            int hours = cal.get(Calendar.HOUR_OF_DAY);
            int minutes = cal.get(Calendar.MINUTE);
            int seconds = cal.get(Calendar.SECOND);


            int currentTime = (int) Double.parseDouble((hours+":"+minutes+":"+seconds));

Answer 1

You cannot do that. If you need to compare times, use LocalTime.

    LocalTime b = LocalTime.of(17, 30);//hh,mm,ss

    LocalTime c = LocalTime.parse("20:30:30");//hh:mm:ss

    System.out.println(b.isBefore(c));//true, also there are methods like compareTo, isAfter

If you need to compare dates, there is also a class called LocalDate . If you need to compare both dates and time, you can use LocalDateTime . Comparing those objects is the same, as comparing two LocalTime obejcts.

LocalTime.of and .parse are static factory methods. They are used to create new instances of LocalTime . From a user perspective, they work like constructors — you call them and you receive in return an object of its class. More about them and constructors you can read here: Java Constructors vs Static Factory Methods .