Different results using Matcher.replaceAll on a literal depending on the Pattern compiled

Question

I would have expected that the results for all the following scenarios would have been the same:
public class PatternMatcher {
    public static void main(String[] args) {
        Pattern p;
        Matcher m;
        // duplicates
        p = Pattern.compile("(.*)");
        m = p.matcher("abc");
        if (m.matches()) System.out.println(p + " : " + m.replaceAll("xyz"));
        // single
        p = Pattern.compile("(.+)");
        m = p.matcher("abc");
        if (m.matches()) System.out.println(p + " : " + m.replaceAll("xyz"));
        // wtf
        p = Pattern.compile("(.*?)");
        m = p.matcher("abc");
        if (m.matches()) System.out.println(p + " : " + m.replaceAll("xyz"));
        // duplicates
        p = Pattern.compile("(.*+)");
        m = p.matcher("abc");
        if (m.matches()) System.out.println(p + " : " + m.replaceAll("xyz"));
        // single
        p = Pattern.compile("^(.*)");
        m = p.matcher("abc");
        if (m.matches()) System.out.println(p + " : " + m.replaceAll("xyz"));
        // duplicates
        p = Pattern.compile("(.*)$");
        m = p.matcher("abc");
        if (m.matches()) System.out.println(p + " : " + m.replaceAll("xyz"));
        // single
        p = Pattern.compile("^(.*)$");
        m = p.matcher("abc");
        if (m.matches()) System.out.println(p + " : " + m.replaceAll("xyz"));
        // single
        p = Pattern.compile("(.(.*).)");
        m = p.matcher("abc");
        if (m.matches()) System.out.println(p + " : " + m.replaceAll("xyz"));
But the results vary depending on the pattern compiled:
(.*) : xyzxyz
(.+) : xyz
(.*?) : xyzaxyzbxyzcxyz
(.*+) : xyzxyz
^(.*) : xyz
(.*)$ : xyzxyz
^(.*)$ : xyz
(.(.*).) : xyz
Since all of the patterns have an all-encompassing capture group, but the replacement string does not have any group references, I was expecting that in every case the replacement string would simply be returned unchanged (so just "xyz").
Have I uncovered a bug in the core library?  or am I misunderstanding how this should be working?

Answer 1

jwenting wrote:
And such is the case here.
"You're doing it wrong, but I'm not going to tell you what it is you're doing wrong nah nah nah"
That's the good thing about long lasting platforms such as Java - APIs become mature because they've been tested and re-tested by thousands of people for more than a decade. And thus when you go to use them and have to think "wtf", you can be almost certain you simply don't understand and meanies in forums can say so without having any ammunition to back up that accusation.