如何删除 Java 中字符串中最后一个数字之后的所有内容？

Question

If I have a String that consists of letters and numbers, how can I get rid of everything after the last number in the String?

Example:

• banana_orange_62_34_wednesday would become banana_orange_62_34
• 1234_4564_www_6_j_1_rrrr would become 1234_4564_www_6_j_1

I tried this so far:

int endIndex = inputXMLFilename.lastIndexOf("\\d+");
inputXMLFilename = inputXMLFilename.substring(0, endIndex);

Answer 1

Use regex replace:

str = str.replaceAll("\\D+$", "");

What the regex means:

• \D means “non-digit”
• + means “one or more of the previous term, greedy (as much of the input as possible)”
• $ means “end of input”

The $ anchors the match to the end, without which this would match (and delete) all non-digits.

---

lastIndexOf() only works with plain text, not regex.

Answer 2

@Test
public void cutAfterLastDigit() {
    String s = "banana_orange_62_34_wednesday";

    Pattern pattern = Pattern.compile("^(.*\\d)");
    Matcher matcher = pattern.matcher(s);
    if (matcher.find()) {
        System.out.println(matcher.group(0));
    }
}