How to Format a Java String with Leading Zero

How to format a Java string with leading zero?

In case you have to do it without the help of a library:

("00000000" + "Apple").substring("Apple".length())

(Works, as long as your String isn't longer than 8 chars.)

How can I pad an integer with zeros on the left?

Use java.lang.String.format(String,Object...) like this:

String.format("%05d", yournumber);

for zero-padding with a length of 5. For hexadecimal output replace the d with an x as in "%05x".

The full formatting options are documented as part of java.util.Formatter.

Add leading zeroes to number in Java?

String.format (https://docs.oracle.com/javase/1.5.0/docs/api/java/util/Formatter.html#syntax)

In your case it will be:

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

• 0 - to pad with zeros
• 3 - to set width to 3

Format floating point number with leading zeros

Number after %0 here defines full width including decimal point, so you need to change it to 7:

System.out.format("%07.3f", 1.23456789);

Java String.format() leading zeros and 1 decimal place

Use DecimalFormat to control the number of mandatory digits:

DecimalFormat df = new DecimalFormat("#000.0");
System.out.println(df.format(50)); // 050.0

where

Symbol  Location    Localized?  Meaning
0       Number      Yes         Digit
#       Number      Yes         Digit, zero shows as absent

How to keep leading zero when incrementing string

You should instead maintain the sequence as a number, i.e. an integer or long, and then format that number with left padded zeroes:

public String generateSequence(int paymentSeq) {
    return "PAY" + String.format("%06d", paymentSeq);
}

int seq = 1;
String nextSeq = generateSequence(seq);

Java how to increment a string of an integer with leading zeros?

Try this.

static final Pattern NUMBER = Pattern.compile("\\d+");

static String increment(String input) {
    return NUMBER.matcher(input)
        .replaceFirst(s -> String.format(
            "%0" + s.group().length() + "d",
            Integer.parseInt(s.group()) + 1));
}

public static void main(String args[]) {
    System.out.println(increment("001"));
    System.out.println(increment("012345"));
    System.out.println(increment("ABC0123"));
}

output:

002
012346
ABC0124

String.format() rounding a double with leading zeros in digits - Java

Use %.4f to perform the rounding you want. This format specifier indicates a floating point value with 4 digits after the decimal place. Half-up rounding is used for this, meaning that if the last digit to be considered is greater than or equal to five, it will round up and any other cases will result in rounding down.

String.format("%.4f", 0.000987654321);

Demo

The %g format specifier is used to indicate how many significant digits in scientific notation are displayed. Leading zeroes are not significant, so they are skipped.

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