Java - how to check if String is valid date?

1. Overview

In this post we can find code which can validate if String contains valid Date based on defined pattern.

2. With SimpleDateFormat

import java.text.ParseException;
import java.text.SimpleDateFormat;

public class Example1 {

    public static void main(String[] args) {

        System.out.println(checkIfDateIsValid("2019-10-13")); // true
        System.out.println(checkIfDateIsValid("2019:10:13")); // false
    }

    private static boolean checkIfDateIsValid(String date) {
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        // With lenient parsing, the parser may use heuristics to interpret
        // inputs that do not precisely match this object's format.
        format.setLenient(false);
        try {
            format.parse(date);
        } catch (ParseException e) {
            return false;
        }
        return true;
    }
}

Output:

true
false

3. With SimpleDateFormat + different patterns

import java.text.ParseException;
import java.text.SimpleDateFormat;

public class Example2 {

    public static void main(String[] args) {

        System.out.println("# Example 1");
        System.out.println(checkIfDateIsValid("yyyy-MM-dd", "2019-10-13")); // true
        System.out.println(checkIfDateIsValid("yyyy-MM-dd", "2019:10:13")); // false

        System.out.println("# Example 2");
        System.out.println(checkIfDateIsValid("yyyy/MM/dd", "2019/10/13")); // true

        System.out.println("# Example 3");
        System.out.println(checkIfDateIsValid("yyyy:MM:dd", "2019:10:13")); // true

        System.out.println("# Example 4");
        System.out.println(checkIfDateIsValid("MM/dd/yyyy", "10/13/2019")); // true
    }

    private static boolean checkIfDateIsValid(String pattern, String date) {
        SimpleDateFormat format = new SimpleDateFormat(pattern);
        // With lenient parsing, the parser may use heuristics to interpret
        // inputs that do not precisely match this object's format.
        format.setLenient(false);
        try {
            format.parse(date);
        } catch (ParseException e) {
            return false;
        }
        return true;
    }
}

Output:

# Example 1
true
false
# Example 2
true
# Example 3
true
# Example 4
true

4. LocalDate - Java 8

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeParseException;

public class Example3 {

    public static void main(String[] args) {

        System.out.println(checkIfDateIsValid("2019-10-13")); // true
        System.out.println(checkIfDateIsValid("2019:10:13")); // false
    }

    private static boolean checkIfDateIsValid(String date) {
        try {
            LocalDate.parse(date, DateTimeFormatter.ISO_DATE);
        } catch (DateTimeParseException e) {
            return false;
        }
        return true;
    }
}

Output:

true
false

5. LocalDate + DateTimeFormatter build-in patterns

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeParseException;

public class Example4 {

    public static void main(String[] args) {

        System.out.println("# Example 1");
        System.out.println(checkIfDateIsValid(
                DateTimeFormatter.ISO_DATE, "2019-10-13")); // true

        System.out.println(checkIfDateIsValid(
                DateTimeFormatter.ISO_DATE, "2019:10:13")); // false

        System.out.println("# Example 2");
        System.out.println(checkIfDateIsValid(
                DateTimeFormatter.BASIC_ISO_DATE, "20191013")); // true

        System.out.println("# Example 3");
        System.out.println(checkIfDateIsValid(
                DateTimeFormatter.ISO_LOCAL_DATE, "2019-10-13")); // true
    }

    private static boolean checkIfDateIsValid(DateTimeFormatter formatter, String date) {
        try {
            LocalDate.parse(date, formatter);
        } catch (DateTimeParseException e) {
            return false;
        }
        return true;
    }
}

Output:

# Example 1
true
false
# Example 2
true
# Example 3
true

6. LocalDate + DateTimeFormatter different patterns

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeParseException;

public class Example5 {

    public static void main(String[] args) {

        System.out.println("# Example 1");
        System.out.println(checkIfDateIsValid("yyyy-MM-dd", "2019-10-13")); // true
        System.out.println(checkIfDateIsValid("yyyy-MM-dd", "2019:10:13")); // false

        System.out.println("# Example 2");
        System.out.println(checkIfDateIsValid("yyyy/MM/dd", "2019/10/13")); // true

        System.out.println("# Example 3");
        System.out.println(checkIfDateIsValid("yyyy:MM:dd", "2019:10:13")); // true

        System.out.println("# Example 4");
        System.out.println(checkIfDateIsValid("MM/dd/yyyy", "10/13/2019")); // true
    }

    private static boolean checkIfDateIsValid(String pattern, String date) {
        try {
            DateTimeFormatter formatter = DateTimeFormatter.ofPattern(pattern);
            LocalDate.parse(date, formatter);
        } catch (DateTimeParseException e) {
            return false;
        }
        return true;
    }
}

Output:

# Example 1
true
false
# Example 2
true
# Example 3
true
# Example 4
true

References

1. SimpleDateFormat - JavaDoc
2. LocalDate - JavaDoc
3. DateTimeFormatter - JavaDoc