Update data in array with an input

LocalDateTime myDateObj = LocalDateTime.now();
DateTimeFormatter myFormatObj = DateTimeFormatter.ofPattern("dd-MMM-yyyy HH:mm:ss");
String dateExit = myDateObj.format(myFormatObj);
System.out.println("Date and time exited: " + dateExit);
dateExit = dateExit[option - 1];

So this is my code, the code with error is this line:

dateExit = dateExit[option - 1]

At first, the system will ask for the user input for name and other details. The date and time entered will be automatically generate by the system and store into the array. And the value for date and time exit is "-" at the beginning because we don't know what time the user is going to exit. Now, when the user want to update the date and time exit, the time will also automatically generate by the system but now my problem is How to update the date and time exit (which generated by the system) to the date and time exit in my array which already have a value inside.

Thanks a lot, a Java Newbie

dateExit in your code is a String object. Its not an array. You can not do dateExit[option - 1] on it.

Maybe this snippet can help you. In it two arrays are initialized with two elements each. One for 2 LocalizedDateTime objects, and one for 2 String objects. LocalizedDateTime is an immutable class, meaning they cannot be changed. You have to create a new object by using LocalDateTime.now() again. If you have initalized an array properly (First two lines) you can access it via the square brackets. As the previous commetators already said, dateExit is not an array thus compiler complains.

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

public class example {

    public static void main(String[] args) throws InterruptedException{

        LocalDateTime[] dateTimeArray = new LocalDateTime[2];
        String[] stringArray = new String[2];
        DateTimeFormatter myFormatObj = DateTimeFormatter.ofPattern("dd-MMM-yyyy HH:mm:ss");
        
        // Get date and time at beginning
        dateTimeArray[0] = LocalDateTime.now();
        stringArray[0] = dateTimeArray[0].format(myFormatObj);
        System.out.println("Date and time begin: " + stringArray[0]);

        Thread.sleep(1000); // Simulate delay

        //  Get date and time at end (exit)
        dateTimeArray[1] = LocalDateTime.now();
        stringArray[1] = dateTimeArray[1].format(myFormatObj);
        System.out.println("Date and time end: " + stringArray[1]);
    }
}

Problem with your code

You have not declared dateExit as String[] but treated it as a String[].

Solution

1. Declare dateExit as String[].
2. Also, for simplicity, I suggest you format LocalDateTime using separate patterns to avoid the need to split the formatted date-time string.

Demo:

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Arrays;

public class Main {
	public static void main(String[] args) {
		// Initial state of dateExit[]
		String[] dateExit = { "-", "-" };

		// Now
		LocalDateTime now = LocalDateTime.now();

		// Assign date string to dateExit[0]
		dateExit[0] = now.format(DateTimeFormatter.ofPattern("dd-MMM-yyyy"));

		// Assign time string to dateExit[1]
		dateExit[1] = now.format(DateTimeFormatter.ofPattern("HH:mm:ss"));

		// Display dateExit[]
		System.out.println(Arrays.toString(dateExit));

		// Display individual elements
		System.out.println("Exit date: " + dateExit[0]);
		System.out.println("Exit time: " + dateExit[1]);
	}
}

Output:

[22-Jul-2020, 11:39:27]
Exit date: 22-Jul-2020
Exit time: 11:39:27