使用模式在Java中解析字符串

Question

I am trying parse out 3 pieces of information from a String .

Here is my code:

text = "H:7 E:7 P:10";
String pattern = "[HEP]:";

Pattern p = Pattern.compile(pattern);

String[] attr = p.split(text);

I would like it to return:

String[0] = "7"
String[1] = "7"
String[2] = "10"

But all I am getting is:

String[0] = ""
String[1] = "7 "
String[2] = "7 "
String[3] = "10"

Any suggestions?

Answer 1

A not-so-elegant solution I just devised:

String text = "H:7 E:7 P:10";
String pattern = "[HEP]:";
text = text.replaceAll(pattern, "");
String[] attr = text.split(" ");

Answer 2

From the javadoc, http://docs.oracle.com/javase/6/docs/api/java/util/regex/Pattern.html#split(java.lang.CharSequence ) :

The array returned by this method contains each substring of the input sequence that is terminated by another subsequence that matches this pattern or is terminated by the end of the input sequence.

You get the empty string first because you have a match at the beginning of the string, it seems.

If I try your code with String text = "AH:7 E:7 P:10" I get indeed:

A 7 7 10

Hope it helps.

Answer 3

I would write a full regular expression like the following:

Pattern pattern = Pattern.compile("H:(\\d+)\\sE:(\\d+)\\sP:(\\d+)");
Matcher matcher = pattern.matcher("H:7 E:7 P:10");
if (!matcher.matches()) {
    // What to do!!??
}
String hValue = matcher.group(1);
String eValue = matcher.group(2);
String pValue = matcher.group(3);

Answer 4

Basing on your comment I take it that you only want to get the numbers from that string (in a particular order?).

So I would recommend something like this:

Pattern p = Pattern.compile("\\d+");
Matcher m = p.matcher("H:7 E:7 P:10");
while(m.find()) {
    System.out.println(m.group());
}