Cannot Format Object as Date in Java
In Java, when trying to format a given object as a date using the DateFormat.format method, you may encounter the following exception:
java.lang.IllegalArgumentException: Cannot format given Object as a Date
This error occurs when the object you attempt to format is not a Date instance. In your case, you are attempting to format a string ("2012-11-17T00:00:00.000-05:00") as a date using a SimpleDateFormat instance configured with the "mm/yyyy" pattern.
Solution
To address this issue, you should use two SimpleDateFormat objects: one for parsing the input string into a Date instance and another for formatting the resulting Date into the desired format:
<code class="java">import java.text.SimpleDateFormat; import java.util.Date; public class DateParser { public static void main(String args[]) { String monthYear = null; // Create input format to parse from "yyy-MM-dd'T'HH:mm:ss.SSSX" SimpleDateFormat inputFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSX"); // Create output format to format to "MM/yyyy" SimpleDateFormat outputFormat = new SimpleDateFormat("MM/yyyy"); String inputText = "2012-11-17T00:00:00.000-05:00"; try { // Parse the input string into a Date object Date date = inputFormat.parse(inputText); // Format the parsed Date into the desired format monthYear = outputFormat.format(date); System.out.println(monthYear); } catch (ParseException e) { System.err.println("Input string is not a valid date: " + e.getMessage()); } } }</code>
This approach separates the parsing and formatting operations, ensuring that the input is properly converted to a Date instance before attempting to format it using the specified pattern.
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