How to take a range of characters from a character array in Java?

Question

I am writing an application that stores a series of values in an Array List object. All of the values are stored as Strings in the array, and one of the parameters is a time stamp which is prefixed with "Timestamp: " followed by the actual Unix timestamp (e.g. 1556849753564)

I need to parse only the Unix timestamp from the Timestamp String object.

Here is what I have tried:

public void parseTimestamp() {
    String lastBlockTimeAsString = (String) HashArray.hashArray.get(HashArray.hashArray.size() - 12);
    char[] timeAsCharArray = lastBlockTimeAsString.toCharArray();
    long lastBlockTime = Long.parseLong(String.valueOf(timeAsCharArray[12] + timeAsCharArray[13] ..... etc ));
}

The HashArray.hashArray.get() call is just pulling the Timestamp object from the Array List. I am pulling the 12th character from the array because that is the start of the timestamp.

In Python I could do something like:

timeAsCharArray[12]:[24]

How can I accomplish this in Java more elegantly than the solution I came up with, which is basically to concatenate each individual character from the array.. Any help would be appreciated!

Would this help you: String timeStampString = "Timestamp: 1556849753564"; String strgTime = timeStampString.split(":\\s+")[1].trim(); long lastBlockTime = Long.parseLong(strgTime);? — DevilsHnd - 退した
– DevilsHnd - 退した, Commented May 3, 2019 at 3:18
Let me try this out and get back to you. Thank you for your response! — apt-getschwifty
– apt-getschwifty, Commented May 3, 2019 at 3:22

Jitendra Singh · Accepted Answer · 2019-05-03 03:29:27Z

1

Not sure why you are trying to convert a string to a character array and then concatenate again. As noted by DevilsHnd, you could either split by removing the "Timestamp: " prefix and getting the "Unix time" or you could replace and then cast. Remember, this assumes that after the replace, user will always have Long numeric value

long lastBlockTime = Long.parseLong(lastBlockTimeAsString.replace("Timestamp: ",""));

answered May 3, 2019 at 3:29

Jitendra Singh

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3 Comments

apt-getschwifty Over a year ago

I think this is going to be what I need. Yes, the timestamp is a long before it gets written to the Array List, and I need it to be parsed back as a long so I can subtract the timestamp in the Array List before the most recent one, from the most recent one. I will try this and let you know if it works, thank you!

Jitendra Singh Over a year ago

If this solved your issue, please accept the answer.

apt-getschwifty Over a year ago

Yup, I just tested it out and got it working. Can't believe I missed that 'replace' method. Thanks a million!

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