How Can I Add Leading Zeros to Numbers in Java?

Adding Leading Zeroes to Numbers in Java

To add leading zeroes to a number in Java, you can use the StringBuilder class to create a new string with the desired number of digits. Here's how you can do it:

static String intToString(int num, int digits) {
    StringBuilder s = new StringBuilder(digits);
    int zeroes = digits - (int) (Math.log(num) / Math.log(10)) - 1; 
    for (int i = 0; i < zeroes; i++) {
        s.append(0);
    }
    s.append(num);
    return s.toString();
}

However, there's a more efficient way to achieve this using the String.format method:

String formatted = String.format("%03d", num);

This format string indicates that the integer num should be formatted as a string with three digits, zero-padding as needed. The 0 before 3d specifies zero-padding, and 3d specifies a width of three digits.

The String.format method is a powerful tool for formatting various types of data into strings. It provides a concise and flexible way to control the output format, including padding, precision, and alignment.

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