Makes a new utility class containing methods related to file reading and filen names

src/main/java/net/knarcraft/ffmpegconverter/utility/FileUtil.java

@@ -0,0 +1,105 @@
+package net.knarcraft.ffmpegconverter.utility;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+
+/**
+ * A class which helps with file handling
+ */
+public final class FileUtil {
+
+    private FileUtil() {
+    }
+
+    /**
+     * Adds parentheses with an integer if the output file already exists
+     * @param targetPath <p>The path the file should ideally be saved at.</p>
+     * @param extension <p>The extension of the target file.</p>
+     * @return <p>A filename guaranteed not to collide with other files.</p>
+     */
+    public static String getNonCollidingFilename(String targetPath, String extension) {
+        File newFile = new File(targetPath);
+        String fileName = stripExtension(targetPath);
+        int i = 1;
+        while (newFile.exists()) {
+            newFile = new File(fileName + "(" + i++ + ")" + "." + extension);
+        }
+        return newFile.toString();
+    }
+
+    /**
+     * Gets filename without extension from File object
+     * @param file <p>A file object.</p>
+     * @return <p>A filename.</p>
+     */
+    public static String stripExtension(File file) {
+        return file.getName().substring(0, file.getName().lastIndexOf('.'));
+    }
+
+    /**
+     * Removes the extension from a file name
+     * @param file <p>A filename.</p>
+     * @return <p>A filename without its extension.</p>
+     */
+    static String stripExtension(String file) {
+        return file.substring(0, file.lastIndexOf('.'));
+    }
+
+    /**
+     * Recursively lists all files in a folder
+     * @param folder <p>The folder to start from.</p>
+     * @param maxRecursions <p>Maximum number of recursions</p>
+     * @return          A list of files
+     */
+    public static File[] listFilesRecursive(File folder, String[] extensions, int maxRecursions) {
+        if (maxRecursions == 0) { return null; }
+        File[] listOfFiles = folder.listFiles((file) -> file.isFile() &&
+                ListUtil.listContains(extensions, (item) -> file.getName().endsWith(item)));
+        if (listOfFiles == null) { return null; }
+        if (maxRecursions > 1) {
+            File[] listOfFolders = folder.listFiles((dir, name) -> new File(dir, name).isDirectory());
+            if (listOfFolders != null) {
+                for (File file : listOfFolders) {
+                    File[] nextLevel = listFilesRecursive(file, extensions, maxRecursions - 1);
+                    if (nextLevel != null) {
+                        listOfFiles = ListUtil.concatenate(listOfFiles, nextLevel);
+                    }
+                }
+            }
+        }
+        return listOfFiles;
+    }
+
+    /**
+     * Reads a file's contents to a string list
+     *
+     * <p>The file must contain the number of lines to read in the first line.</p>
+     *
+     * @param fileName <p>The file to read.</p>
+     * @return <p>A string list where each element is one line of the file.</p>
+     * @throws IOException <p>If the file cannot be read.</p>
+     */
+    public static String[] readFileLines(String fileName) throws IOException {
+        BufferedReader reader = new BufferedReader(new InputStreamReader(getResourceAsStream(fileName)));
+        int numberOfLines = Integer.parseInt(reader.readLine());
+        String[] lines = new String[numberOfLines];
+        for (int i = 0; i < lines.length; i++) {
+            lines[i] = reader.readLine();
+        }
+        return lines;
+    }
+
+    /**
+     * Gets a resource as an InputStream
+     * @param resourceName <p>The name of the resource you want to read.</p>
+     * @return <p>An input stream which can be used to access the resource.</p>
+     */
+    private static InputStream getResourceAsStream(String resourceName) {
+        ClassLoader classloader = Thread.currentThread().getContextClassLoader();
+        return classloader.getResourceAsStream(resourceName);
+    }
+
+}