How to Remove All Leading Zeroes in a String

How to remove leading zeros from alphanumeric text?

Regex is the best tool for the job; what it should be depends on the problem specification. The following removes leading zeroes, but leaves one if necessary (i.e. it wouldn't just turn "0" to a blank string).

s.replaceFirst("^0+(?!$)", "")

The ^ anchor will make sure that the 0+ being matched is at the beginning of the input. The (?!$) negative lookahead ensures that not the entire string will be matched.

Test harness:

String[] in = {
    "01234",         // "[1234]"
    "0001234a",      // "[1234a]"
    "101234",        // "[101234]"
    "000002829839",  // "[2829839]"
    "0",             // "[0]"
    "0000000",       // "[0]"
    "0000009",       // "[9]"
    "000000z",       // "[z]"
    "000000.z",      // "[.z]"
};
for (String s : in) {
    System.out.println("[" + s.replaceFirst("^0+(?!$)", "") + "]");
}

How to remove all leading zeroes in a string

ltrim:

$str = ltrim($str, '0');

Remove leading zero in Java

I would consider checking for that case first. Loop through the string character by character checking for a non "0" character. If you see a non "0" character use the process you have. If you don't, return "0". Here's how I would do it (untested, but close)

boolean allZero = true;
for (int i=0;i<value.length() && allZero;i++)
{
    if (value.charAt(i)!='0')
        allZero = false;
}
if (allZero)
    return "0"
...The code you already have

Remove leading zeros from a number in a string

I hope this works:

try {
   int i = Integer.parseInt(yourString);
   System.out.println(i);
} catch(NumberFormatException e) {
   // the string is not a number
}

How to remove leading zeros from Strings in java

I am aware that we can use String Utils library. But what if the String has only "0". It returns " ". Do we have any other way to remove leading 0 for all other strings except for "0".

You can create your own utility method that does exactly what you want.

Well you still haven't answered my question about whether the department can be alphanumeric or just numeric.

Based on your examples you could just convert the String to an Integer. The toString() implementation of an Integer removes leading zeroes:

    System.out.println( new Integer("008").toString() );
    System.out.println( new Integer("000").toString() );
    System.out.println( new Integer("111").toString() );

If the string can contain alphanumeric the logic would be more complex, which is why it is important to define the input completely.

For an alphanumeric string you could do something like:

StringBuilder sb = new StringBuilder("0000");

while (sb.charAt(0) == '0' && sb.length() > 1)
    sb.deleteCharAt(0);

System.out.println(sb);

Or, an even more efficient implementation would be something like:

int i = 0;

while (product.charAt(i) == '0' && i < product.length() - 1)
    i++;

System.out.println( product.substring(i) );

The above two solutions are the better choice since they will work for numeric and alphanumeric strings.

Or you could even use the StringUtils class to do what you want:

String result = StringUtils.removeleadingZeroes(...) // whatever the method is

if (result.equals(" "))
    result = "0";

return result;

In all solutions you would create a method that you pass parameter to and then return the String result.

Remove leading zeroes from a string

Use str::trim_start_matches

fn main() {
    assert_eq!("00foo1bar11".trim_start_matches('0'), "foo1bar11");
}

Playground

How to remove leading zeros with long string

By splitting the given string into array and then remove the leading zeroes, is working fine.

where removeLeadingZeros is:

public static  String removeLeading(String str) {
String regex = "^0+(?!$)";
String x[] = str.split(" ");
StringBuilder z = new StringBuilder();
    
for(String y:x) {
    str = y.replaceAll(regex, "");
    z.append(" " + str);
}
return z.toString();
}

How to remove leading and trailing zeros in a string? Python

What about a basic

your_string.strip("0")

to remove both trailing and leading zeros ? If you're only interested in removing trailing zeros, use .rstrip instead (and .lstrip for only the leading ones).

More info in the doc.

You could use some list comprehension to get the sequences you want like so:

trailing_removed = [s.rstrip("0") for s in listOfNum]
leading_removed = [s.lstrip("0") for s in listOfNum]
both_removed = [s.strip("0") for s in listOfNum]