Created
August 15, 2020 17:41
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Just a simple autoClose test
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| import java.io.IOException; | |
| import java.nio.file.Files; | |
| import java.nio.file.Path; | |
| import java.nio.file.Paths; | |
| import java.util.List; | |
| import java.util.Optional; | |
| import java.util.Scanner; | |
| import java.util.stream.Collectors; | |
| import java.util.stream.Stream; | |
| public class ReadFile { | |
| private static final long HEAD_LINES = 3; | |
| public static void main(String[] args) { | |
| final Scanner scanner = new Scanner(System.in); | |
| do { | |
| System.out.print("Input text file absolute name(Press Ctrl+C to exit): "); | |
| final String nextLine = scanner.nextLine(); | |
| System.out.println(nextLine); | |
| final Path path = Paths.get(nextLine); | |
| if (path.toFile().exists()) { | |
| System.out.println(path + " is exist, try to read it as text file"); | |
| if (isCloseMode(args)) { | |
| System.out.println("read first " + HEAD_LINES + "lines with close():"); | |
| Optional.ofNullable(readWithClose(path, HEAD_LINES)) | |
| .map(strings -> String.join("\n", strings)) | |
| .ifPresent(System.out::println); | |
| } else { | |
| System.out.println("read first " + HEAD_LINES + "lines without close():"); | |
| Optional.ofNullable(readWithOutClose(path, HEAD_LINES)) | |
| .map(strings -> String.join("\n", strings)) | |
| .ifPresent(System.out::println); | |
| } | |
| System.out.println("\n==========\n=========="); | |
| } else { | |
| System.out.println(path + " is not exist, try again!"); | |
| } | |
| } while (scanner.hasNext()); | |
| } | |
| private static boolean isCloseMode(String[] args) { | |
| return args != null && args.length > 0; | |
| } | |
| private static List<String> readWithOutClose(Path filePath, long headLines) { | |
| try { | |
| return Files.lines(filePath) | |
| .limit(headLines) | |
| .collect(Collectors.toList()); | |
| } catch (IOException e) { | |
| System.err.println(String.format("read file '%s' failed: %s", filePath, e)); | |
| return null; | |
| } | |
| } | |
| private static List<String> readWithClose(Path filePath, long headLines) { | |
| try (Stream<String> stream = Files.lines(filePath)) { | |
| return stream | |
| .limit(headLines) | |
| .collect(Collectors.toList()); | |
| } catch (IOException e) { | |
| System.err.println(String.format("read file '%s' failed: %s", filePath, e)); | |
| return null; | |
| } | |
| } | |
| } |
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