Use variables in pattern matcher

Question

I have the following: ``` if (mobile.matches("[0-9]{6,20}")) { ... } ``` But would like to replace the {6,20} with variable values due to them been dynamic in some cases. I.e. ``` int minValue = 11; int maxValue = 20 if (mobile.matches("[0-9]{minValue,maxValue}")) { ... } ``` How can I include variables in the Reg Exp? Thanks

Accepted Answer

Use Java's simple string concatenation, using the plus sign.

```
if (mobile.matches("[0-9]{" + minValue + "," + maxValue + "}")) {
```

Indeed, as Michael suggested compiling it is better for performance if you use it a lot.

```
Pattern pattern = Pattern.compile("[0-9]{" + minValue + "," + maxValue + "}");
```

Then use it when needed like this:

```
Matcher m = pattern.matcher(mobile);
if (m.matches()) {
```

Use variables in pattern matcher

Solution

Problem