Java Program to Convert Time from 24-Hour to 12-Hour Format

In the previous article, we have seen Java Program to Covert Time From 12-hour Format to 24-hour Format

In this article we are going to see how convert time from 24-hour to 12-hour format using Java programming language.

Java Program to Convert Time from 24-Hour to 12-Hour Format

It is considered that the time format is given in hh:mm:ss format.

Let’s see different ways to convert time from 24-hour to 12-hour format.

By Using Static Input Value
By Using User Input Value

Method-1: Java Program to Convert Time from 24-Hour to 12-Hour Format By Using Static Input Value

Approach:

Initialize time value.
Call the method for conversion.
Check if the time is in AM or PM by comparing the hh value with 12.
Do hh = hh%12.
If hh == 0 i.e., AM:
1. Print 12, and print the minutes and seconds as it is.
Else if it’s in PM.
1. If the hh as it is.
2. Print the rest values as it is.

Program:

public class Main
{
    static void convert(String str) 
    {
        // Get Hours
        int h1 = (int) str.charAt(0) - '0';
        int h2 = (int) str.charAt(1) - '0';

        int hh = h1 * 10 + h2;

        // check if the time should be in AM or PM
        String mrdn;
        if (hh < 12)
        {
            mrdn = "AM";
        } else
            mrdn = "PM";

        hh %= 12;

        // Handle 00 and 12 case separately
        if (hh == 0)
        {
            System.out.print("12");

            // Printing minutes and seconds
            for (int i = 2; i < 8; ++i) 
            {
                System.out.print(str.charAt(i));
            }
        }
        else
        {
            System.out.print(hh);
            // Printing minutes and seconds
            for (int i = 2; i < 8; ++i) {
                System.out.print(str.charAt(i));
            }
        }

        // After time is printed print Meridien
        System.out.println(" " + mrdn);
    }

    public static void main(String ar[])
    {

        // 24 hour format
        String str = "13:58:28";
        convert(str);

    }
}

Output:

1:58:28 PM

Method-2: Java Program to Convert Time from 24-Hour to 12-Hour Format By Using User Input Value

Approach:

Create Scanner class object.
Take user input for hour, minute and seconds and whether it’s am or pm.
If the user has given single value in input pad a zero to the left.
Convert the AM/PM value to upper case(for easier comparison).
Call the method for conversion.
Check if the time is in AM or PM by comparing the hh value with 12.
Do hh = hh%12.
If hh == 0 i.e., AM:
1. Print 12, and print the minutes and seconds as it is.
Else if it’s in PM.
1. If the hh as it is.
2. Print the rest values as it is.

Program:

import java.util.Scanner;

public class Main 
{
    static void convert(String str) 
    {
        // Get Hours
        int h1 = (int) str.charAt(0) - '0';
        int h2 = (int) str.charAt(1) - '0';

        int hh = h1 * 10 + h2;

        // check if the time should be in AM or PM
        String mrdn;
        if (hh < 12) 
        {
            mrdn = "AM";
        } else
            mrdn = "PM";

        hh %= 12;

        // Handle 00 and 12 case separately
        if (hh == 0)
        {
            System.out.print("12");

            // Printing minutes and seconds
            for (int i = 2; i < 8; ++i)
            {
                System.out.print(str.charAt(i));
            }
        } 
        else 
        {
            System.out.print(hh);
            // Printing minutes and seconds
            for (int i = 2; i < 8; ++i) 
            {
                System.out.print(str.charAt(i));
            }
        }

        // After time is printed print Meridien
        System.out.println(" " + mrdn);
    }

    public static void main(String[] args) 
    {
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter the time in 24 hour format");
        System.out.println("Enter hours: ");
        String hh = sc.nextLine();
        hh = padZero(hh);
        System.out.println("Enter minutes: ");
        String mm = sc.nextLine();
        mm = padZero(mm);
        System.out.println("Enter seconds: ");
        String ss = sc.nextLine();
        ss = padZero(ss);

        String time = hh + ":" + mm + ":" + ss;
        System.out.print("Time in 12-hour format is ");
        convert(time);
    }

    private static String padZero(String n)
    {
        if (n.length() == 1)
            n = "0" + n;
        return n;
    }
}

Output:

Enter the time in 24 hour format
Enter hours: 
14
Enter minutes: 
32
Enter seconds: 
12
Time in 12-hour format is 2:32:12 PM

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