51 lines
1.1 KiB
Java
51 lines
1.1 KiB
Java
// strings/JGrep.java
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// (c)2021 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://OnJava8.com for more book information.
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// A very simple version of the "grep" program
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// {java JGrep
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// WhitherStringBuilder.java "return|for|String"}
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import java.util.regex.*;
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import java.nio.file.*;
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import java.util.stream.*;
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public class JGrep {
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public static void
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main(String[] args) throws Exception {
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if(args.length < 2) {
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System.out.println(
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"Usage: java JGrep file regex");
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System.exit(0);
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}
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Pattern p = Pattern.compile(args[1]);
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Matcher m = p.matcher("");
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// Iterate through the lines of the input file:
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Files.readAllLines(Paths.get(args[0])).forEach(
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line -> {
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m.reset(line);
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while(m.find())
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System.out.println(
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m.group() + ": " + m.start());
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}
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);
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}
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}
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/* Output:
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String: 18
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String: 20
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String: 9
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String: 25
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String: 4
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for: 4
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String: 8
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return: 4
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String: 9
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String: 25
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String: 4
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String: 31
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for: 4
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String: 8
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return: 4
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String: 20
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*/
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