Question

I want to replace all the characters in a Java String with * character. So it shouldn’t matter what character it is, it should be replaced with a *.

I know there are heaps of examples there on internet but have not one that replaces every character and I have tried myself but no success.

Answer 1

Java 11 and later

str = "*".repeat(str.length());

Note: This replaces newlines \n with *. If you want to preserve \n, see solution below.

Java 10 and earlier

str = str.replaceAll(".", "*");

This preserves newlines.

To replace newlines with * as well in Java 10 and earlier, you can use:

str = str.replaceAll("(?s).", "*");

The (?s) doesn’t match anything but activates DOTALL mode which makes . also match \n.