如何检查字符串只包含数字和小数点？

Question

For example I want to check that my when I split my string that the first part only contains numbers and decimal points.

I have done the following

String[] s1 = {"0.12.13.14-00000001-00000", "0.12.13.14-00000002-00000"};

        String[] parts_s1 = s1.split("-");
        System.out.println(parts_s1[0]);
        if(parts_s1[0].matches("[0-9]")

But thats only checking for numbers and not decimals. How can I also check for decimals in this? For example I want to check for 0.12.13.14 that it works and something like 0.12.13.14x will not work.

Answer 1

Add the dot character in the regex as follows:

if(parts_s1[0].matches("[0-9.]*")) {     // match a string containing digits or dots

The * is to allow multiple digits/decimal points.

In case at least one digit/decimal point is required, replace * with + for one or more occurrences.

EDIT:

In case the regex needs to match (positive) decimal numbers (not just arbitrary sequences of digits and decimal points), a better pattern would be:

if(parts_s1[0].matches("\\d*\\.?\\d+")) {    // match a decimal number

Note that \\\\d is equivalent to [0-9] .

Answer 2

You can simply add a dot to the list of allowed characters:

if(parts_s1[0].matches("[.0-9]+")

This, however, would match strings that are composed entirely of dots, or have sequences of multiple dots.

Answer 3

You can use this regex:

\\d+(\\.\\d+)*

Code:

if(parts_s1[0].matches("\\d+(\\.\\d+)*") {...}