making ideas into a digitized reality
Java SE tipps and triks
There are a lot of examples how to read a file content in Java 8. The most common one is
|
1 2 3 4 5 6 7 |
import java.io.IOException; import java.nio.file.Files; import java.nio.file.Paths; public static void main(String[] args) throws IOException { String content = new String(Files.readAllBytes(Paths.get("duke.java"))); } |
Use always a charset with String to Byte array transformations and vice versa...
|
1 2 3 4 5 6 7 8 9 10 11 12 |
distance = new long[points.size()][points.size()]; for (int i = -1; ++i < points.size();) { int x1 = points.get(i).getX(); int y1 = points.get(i).getY(); distance[i][i] = 0; for (int j = -1; ++j < i;) { int x2 = points.get(j).getX(); int y2 = points.get(j).getY(); distance[i][j] = Math.max(Math.abs(x1 - x2) * costX, Math.abs(y1 - y2) * costY); distance[j][i] = distance[i][j]; } } |
CostX and CostY – are the axle weight. E.g .: maximum axis velocity of the robot. An edge is calculated by the TSPAction class. The recursive function returns no results , so TSPAction...
Short snippet how to leave 100 newest text files in directory and delete others with help of Java 8 lambda.
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 |
String pattern = "**.txt"; int fileCapacity = 100; Path path = Paths.get("your/directory/"); PathMatcher ldfMatcher = FileSystems.getDefault().getPathMatcher("glob:" + pattern); try (DirectoryStream files = Files.newDirectoryStream(path)) { StreamSupport.stream(files.spliterator(), false) // sequential stream .filter(file -> Files.isRegularFile(file) && ldfMatcher.matches(file)) .sorted((Path o1, Path o2) -> { try { return Files.getLastModifiedTime(o2).compareTo(Files.getLastModifiedTime(o1)); } catch (IOException ex) { // exception handling... } }) .skip(fileCapacity) .forEach(file -> { try { Files.delete(file); } catch (IOException ex) { // exception handling... } }); } catch (IOException ex) { // exception handling... } |