Java Date异常处理尝试捕获

Question

Is there some sort of exception in Java to catch an invalid Date object? I'm trying to use it in the following method, but I don't know what type of exception to look for. Is it a ParseException.

public boolean setDate(Date date) {
        this.date = date;                
        return true;
    }

Answer 1

In the method you provide, there is no way to catch an exception, because none will be thrown by the simple assignment. All you can do is maybe the below change:

if(date == null) return false;

But even that's not graceful. You may want to do something with this.date or throw an exception up if that's the desired behavior.

What you are really seeking is either:

1. ParseException - thrown by a DateFormat object when it attempts to parse() , which would happen before your set method
2. IllegalArgumentException - thrown by a SimpleDateFormat constructor, again it would happen before your set method. Indicates you provided an invalid format string.

You'd want to catch one of those (probably #1). But it has to happen before your method call. Once you have a Date object, it is either null or valid.

Answer 2

This might not be related to the original question. But you must notice the method name, which is setDate() . Do you think it sounds like it will return something? Or if it may, then do you think its a good idea to return a boolean there? IMO, do something like this,

public void setDate(Date date) {
    this.date = date;                
}

public boolean isDateNull() { // or something
    return this.date == null;                
}

Answer 3

In this method, there is no need to worry about an exception. The date is already created by the time you get into this method. If you are parsing a date, it would have done outside of this code. The best you could do is make sure the date is not null.

Answer 4

It depends on what you mean by an invalid date. Did you mean to give us a method signature that looked more like this?

public void setDate(String date) throws ParseException {
   this.date = SomeDateFormat.getInstance().format(date);
}

Otherwise, as the others stated the simple act of assigning a Java date object to a field shouldn't be exceptional as it is either an instance of Date already, or null.

If you are just trying to parse a string into a java.util.Date, look at DateFormat , FastDateFormat (apache, thread safe), or Joda Time.