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Generate Random Times in Java

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[ Code Example - Quick Summary ]

Language: Java

What: Generate random times in Java using LocalTime and Random. Covers 12-hour, 24-hour formats, and time validation for testing.

Try it: Use our interactive Times generator or integrate this code into your Java application.

Generate random times in Java using LocalTime and Random. Covers 12-hour, 24-hour formats, and time validation for testing. Looking for other languages? Check our code examples in PHP , JavaScript , Python , C# , C++ , Ruby and Go or use our interactive web generator.

Java Code Example

import java.time.LocalTime;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class TimeGenerator {
    private static final Random random = new Random();

    // Generate random time (24-hour format HH:MM:SS)
    public static LocalTime randomTime24() {
        int hour = random.nextInt(24);
        int minute = random.nextInt(60);
        int second = random.nextInt(60);
        return LocalTime.of(hour, minute, second);
    }

    // Generate random time as formatted string
    public static String randomTimeString() {
        LocalTime time = randomTime24();
        return time.format(DateTimeFormatter.ofPattern("HH:mm:ss"));
    }

    // Generate random time (12-hour format with AM/PM)
    public static String randomTime12() {
        int hour = random.nextInt(12) + 1;
        int minute = random.nextInt(60);
        String ampm = random.nextBoolean() ? "AM" : "PM";
        return String.format("%02d:%02d %s", hour, minute, ampm);
    }

    // Generate random time within business hours (9 AM - 5 PM)
    public static LocalTime randomBusinessTime() {
        int hour = random.nextInt(9) + 9; // 9-17
        int minute = random.nextInt(60);
        return LocalTime.of(hour, minute);
    }

    // Validate time string (HH:MM:SS)
    public static boolean isValidTime(String time) {
        try {
            LocalTime.parse(time, DateTimeFormatter.ofPattern("HH:mm:ss"));
            return true;
        } catch (Exception e) {
            return false;
        }
    }

    // Generate multiple random times
    public static List<LocalTime> generateTimes(int count) {
        List<LocalTime> times = new ArrayList<>();
        for (int i = 0; i < count; i++) {
            times.add(randomTime24());
        }
        return times;
    }

    public static void main(String[] args) {
        System.out.println("24-hour: " + randomTimeString());
        System.out.println("12-hour: " + randomTime12());
        System.out.println("Business: " + randomBusinessTime());
        System.out.println("Valid: " + isValidTime("14:30:45"));
        System.out.println("Batch: " + generateTimes(3));
    }
}

[EXPLANATION]

Java uses LocalTime.of(hour, minute, second) to create time objects. Random.nextInt(bound) generates hours (0-23), minutes (0-59), seconds (0-59). DateTimeFormatter formats output. String.format("%02d") adds leading zeros. LocalTime.parse() validates time strings. Java 8+ time API is preferred over legacy Date. LocalTime is immutable and thread-safe.

Expected Output

24-hour: 14:23:45
12-hour: 09:15 AM
Business: 11:30
Valid: true
Batch: [08:45:12, 16:20:33, 22:10:05]

Common Use Cases

Generate times for Spring Boot scheduling tests
Create time fields for JPA entity testing
Generate appointment times for booking systems
Test time validation in enterprise applications
Create working hours for employee management

Important Notes

LocalTime represents time without date or timezone
DateTimeFormatter.ofPattern("HH:mm:ss") for 24-hour format
Random.nextBoolean() returns true/false for AM/PM
LocalTime is immutable and thread-safe
Use LocalTime.now() for current time

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Don't want to write code? Use our free web-based Times generator with instant results.

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