How to include the current date when logging exceptions to a file using FileOutputStream in Java?

There are several logging frameworks that can be used to record data to a file. You can also define your own method. In either case, you can useLocalDateTimeclass.

It is an immutable class representing date and time, storing date and time asyear-month-day-hour-minute-second.now()This method of the class returns the current date and time.

Use this method to append the current date and time to your exception message and write it to the required file.

Example

import java.io.FileOutputStream;
import java.io.IOException;
import java.time.LocalDateTime;
import java.util.Arrays;
import java.util.Scanner;
public class LoggingToFile {
　　　private static void writeLogToFile(Exception e) throws IOException {
　　　　　　FileOutputStream writer = new FileOutputStream("ExceptionLog.txt");
　　　　　　byte bytes[] = (LocalDateTime.now();+: "+e.toString().getBytes();
　　　　　　writer.write(bytes);
　　　　　　System.out.println("Exception logged to your file");
　　　}
　　　public static void main(String [] args) throws IOException {
　　　　　　Scanner sc = new Scanner(System.in);
　　　　　　int[] arr = {10,　20,　30,　2, 0,　8};
　　　　　　System.out.println("Array: "+Arrays.toString(arr));
　　　　　　System.out.println("Choose numerator and denominator (not 0) from this array (enter positions 0 to　5});
　　　　　　int a = sc.nextInt();
　　　　　　int b = sc.nextInt();
　　　　　　try {
　　　　　　　　　int result = (arr[a])/(arr[b]);
　　　　　　　　　System.out.println("Result of "+arr[a]+"/"+arr[b]+: "+result);
　　　　　　}catch(ArrayIndexOutOfBoundsException ex) {
　　　　　　　　　System.out.println("Warning: You have chosen a position which is not in the array");
　　　　　　　　　writeLogToFile(ex);
　　　　　　}catch(ArithmeticException ex) {
　　　　　　　　　System.out.println("Warning: You cannot divide a number with 0");
　　　　　　　　　writeLogToFile(ex);
　　　　　　}
　　　}
}

Output Result

Enter　3　integer values one by one:
Array: [10,　20,　30,　2, 0,　8]
Choose numerator and denominator (not 0) from this array (enter positions 0 to　5)
1
4
Warning: You cannot divide a number with 0
Exception logged to your file