Add leading zeroes to number in Java?

To add leading zeroes to a number in Java, you can use the format method of the String class, along with a format string that specifies the desired length and padding character.

For example, to add leading zeroes to a number such that the resulting string is always 6 characters long, you can use the following code:

int number = 123;
String result = String.format("%06d", number);  // result is "000123"

The format string "%06d" specifies that the number should be formatted as a decimal integer (d) and padded with zeroes (0) on the left to a minimum width of 6 characters.

You can also use the printf method of the PrintStream class to achieve the same result:

int number = 123;
String result = String.format("%06d", number);  // result is "000123"

Keep in mind that these methods only work for numerical types such as int, long, and float. If you want to pad a string with leading zeroes, you can use a similar format string and pass the string as the argument:

String str = "abc";
String result = String.format("%06s", str);  // result is "000abc"

This will pad the string with zeroes on the left to a minimum width of 6 characters. If the string is already longer than the specified width, it will not be truncated.