Adds a new function for deleting files recursively

src/main/java/net/knarcraft/minecraftserverlauncher/utility/CommonFunctions.java

@@ -16,7 +16,7 @@ import java.nio.file.StandardCopyOption;
 import java.util.Scanner;
 
 /**
- * A holding class for methods shared between classes.
+ * A holding class for methods shared between classes
  *
  * @author Kristian Knarvik <kristian.knarvik@knett.no>
  * @version 1.0.0
@@ -199,10 +199,11 @@ public final class CommonFunctions {
         StringBuilder text = new StringBuilder();
         char[] readCharacters = new char[1000];
         while (reader.ready()) {
-            reader.read(readCharacters);
+            if (reader.read(readCharacters) > 0) {
                 text.append(readCharacters);
                 readCharacters = new char[1000];
             }
+        }
         return text.toString().trim();
     }
 
@@ -244,4 +245,31 @@ public final class CommonFunctions {
     public static boolean nameIsValid(String name) {
         return !name.equals("") && name.matches("[^!?;,]+");
     }
+
+    /**
+     * Removes all files within a folder
+     * @param target <p>The folder to delete from</p>
+     */
+    static void removeFilesRecursively(File target) {
+        File[] oldFiles = target.listFiles();
+        if (oldFiles == null) {
+            throw new IllegalArgumentException("Unable to list files in directory");
+        }
+        for (File file : oldFiles) {
+            if (file.isFile()) {
+                if (!file.delete()) {
+                    throw new IllegalArgumentException("Unable to delete a file from the directory");
+                }
+            }
+        }
+        for (File file : oldFiles) {
+            if (file.isDirectory()) {
+                removeFilesRecursively(file);
+                if (!file.delete()) {
+                    throw new IllegalArgumentException("Unable to delete a file from the directory");
+                }
+            }
+        }
+    }
+
 }

src/main/java/net/knarcraft/minecraftserverlauncher/utility/Updater.java

@@ -5,7 +5,6 @@ import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
 import com.google.gson.JsonParser;
 import net.knarcraft.minecraftserverlauncher.Main;
-import net.knarcraft.minecraftserverlauncher.userinterface.GUI;
 
 import javax.swing.*;
 import java.io.*;

src/test/java/net/knarcraft/minecraftserverlauncher/utility/JarDownloaderTest.java

@@ -109,12 +109,6 @@ public class JarDownloaderTest {
         if (!target.exists() && !target.mkdirs()) {
             throw new IllegalArgumentException("Unable to create the test files directory");
         }
-        File[] oldFiles = target.listFiles();
-        if (oldFiles == null) {
-            throw new IllegalArgumentException("Unable to list files in jar test directory");
-        }
-        for (File file : oldFiles) {
-            assertTrue(file.delete());
-        }
+        CommonFunctions.removeFilesRecursively(target);
     }
 }