Clever Geek Handbook

Pattern / Matcher in Java?

I have a specific text in Java and I want to use a template and matcher to extract something from it. This is my program:

public String getItemsByType(String text, String start, String end) {

    String patternHolder;
    StringBuffer itemLines = new StringBuffer();

    patternHolder = start + ".*" + end;

    Pattern pattern = Pattern.compile(patternHolder);
    Matcher matcher = pattern.matcher(text);

    while (matcher.find()) {
        itemLines.append(text.substring(matcher.start(), matcher.end())
                + "\n");
    }

    return itemLines.toString();
}

This code works completely WHEN if the search text is on one line, for example:

String text = "My name is John and I am 18 years Old"; 

getItemsByType(text, "My", "John");

immediately extracts the text "My name is John" from the text. However, when my text looks like this:

String text = "My name\nis John\nand I'm\n18 years\nold"; 

getItemsByType(text, "My", "John");

This does not capture anything, as "Mine" and "John" are on different lines. How can I solve this?

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2 answers


Use this instead:

Pattern.compile(patternHolder, Pattern.DOTALL);


From the javadoc, the flag DOTALL

means:

Turns on dotall mode.

In the mode hitherto, expression. matches any character, including the line terminator. By default, this expression does not match line terminators.

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Use Pattern.compile(patternHolder, Pattern.DOTALL)

to compile the template. Thus, the point will correspond to the new line. By default, newline is treated in a special way and does not match point.



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