Java Reference
In-Depth Information
need to complete
newJoke
is a way to copy the text from
joke
that comes after the last subsequence that
was found. The
appendTail()
method for the
Matcher
object does that:
m.appendTail(newJoke);
This copies the text starting with the
m.end()
index position from the last successful match through to
the end of the string. Thus this statement copies the segment
"smells horrible."
from
joke
to
newJoke
.
You can put all that together and run it.
TRY IT OUT: Search and Replace
Here's the code I have just discussed assembled into a complete program:
import java.util.regex.Pattern;
import java.util.regex.Matcher;
class SearchAndReplace {
public static void main(String args[]) {
String joke = "My dog hasn't got any nose.\n"
+"How does your dog smell then?\n"
+"My dog smells horrible.\n";
String regEx = "dog";
Pattern doggone = Pattern.compile(regEx);
Matcher m = doggone.matcher(joke);
StringBuffer newJoke = new StringBuffer();
while(m.find()) {
m.appendReplacement(newJoke, "goat");
}
m.appendTail(newJoke);
System.out.println(newJoke);
}
}
SearchAndReplace.java
When you compile and execute this you should get the following output:
My goat hasn't got any nose.
How does your goat smell then?
My goat smells horrible.
How It Works
Each time the
find()
method in the
while
loop condition returns
true
, you call the
appendReplace-
ment()
method for the
Matcher
object
m
. This copies characters from
joke
to
newJoke
, starting at the
index position where
find()
started searching, and ending at the character preceding the first character
