auto closable not working with Scanner - java.util.scanner

Question

package org.test;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class RegTest {
public static void main(String[] args) throws InterruptedException {
String str = readLine("Enter String :");
String patternString = readLine("Enter pattern to search :");
Pattern pattern = Pattern.compile(patternString);
Matcher matcher = pattern.matcher(str);
System.out.print("match positions: "); // matches positions
while(matcher.find()) {
System.out.print(matcher.start() + " ");
}
System.out.println("");
}
static String readLine(String message){
String strLine;
try (Scanner in = new Scanner(System.in)) {
System.out.println(message);
strLine= in.nextLine();
}
return strLine;
}
}
Did not work.
Output is :
Enter String :
wewew
Enter pattern to search :
Exception in thread "main" java.util.NoSuchElementException: No line found
at java.util.Scanner.nextLine(Scanner.java:1585)
at org.test.RegTest.readLine(RegTest.java:39)
at org.test.RegTest.main(RegTest.java:22)

Answer 1

When the try-with-resources (autoclosable) closes the scanner it also closes the inputstream making it unavailable for use in the future.
As System.in is a global inputstream it means the second scanner can't read any thing from the inputstream because it has been closed and it throws the exception.
I would change the code to reuse the sanner for both reads.
public static void main(String[] args) throws InterruptedException {
try (Scanner in = new Scanner(System.in)) {
String str = readLine(in, "Enter String :");
String patternString = readLine(in, "Enter pattern to search :");
Pattern pattern = Pattern.compile(patternString);
Matcher matcher = pattern.matcher(str);
System.out.print("match positions: "); // matches positions
while (matcher.find()) {
System.out.print(matcher.start() + " ");
}
System.out.println("");
}
}
static String readLine(Scanner in, String message) {
String strLine;
System.out.println(message);
strLine = in.nextLine();
return strLine;
}