Makes a new utility class containing methods related to strings

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

@@ -0,0 +1,28 @@
+package net.knarcraft.ffmpegconverter.utility;
+
+/**
+ * A class which helps with operations on strings
+ */
+final class StringUtil {
+
+    private StringUtil() {
+    }
+
+    /**
+     * Finds all substrings between two substrings in a string
+     * @param string <p>The string containing the substrings.</p>
+     * @param start <p>The substring before the wanted substring.</p>
+     * @param end <p>The substring after the wanted substring.</p>
+     * @return <p>A list of all occurrences of the substring.</p>
+     */
+    static String[] stringBetween(String string, String start, String end) {
+        int startPos = string.indexOf(start) + start.length();
+        if (!string.contains(start) || string.indexOf(end, startPos) < startPos) {
+            return new String[]{};
+        }
+        int endPos = string.indexOf(end, startPos);
+        String outString = string.substring(startPos, endPos).trim();
+        String nextString = string.substring(endPos + end.length());
+        return ListUtil.concatenate(new String[]{outString}, stringBetween(nextString, start, end));
+    }
+}