Issue 4231 - Fix unstable FilterEngineTest.testSetRemoveFilterChangeCallback

libadblockplus-android/src/org/adblockplus/libadblockplus/FileSystemHelper.java

+/*
+ * This file is part of Adblock Plus <https://adblockplus.org/>,
+ * Copyright (C) 2006-2016 Eyeo GmbH
+ *
+ * Adblock Plus is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * Adblock Plus is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.adblockplus.libadblockplus;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.NoSuchElementException;
+import java.util.Scanner;
+import java.util.UUID;
+
+public class FileSystemHelper

[anton, 2016/07/12 10:49:41]

could be called 'FileSystemUtils' in order to be consistent with existing
'Utils' class

+{
+    /**
+     * Read all the file data to string
+     *
+     * @param file path to read data
+     * @return file data
+     * @throws java.io.FileNotFoundException
+     */
+    public String readFile(File file) throws FileNotFoundException
+    {
+        Scanner scanner = null;
+        try
+        {
+            scanner = new Scanner(file);
+            return scanner.useDelimiter("\\A").next();
+        }
+        catch (NoSuchElementException e)
+        {
+            return "";
+        }
+        finally
+        {
+            if (scanner != null)
+                scanner.close();
+        }
+    }
+
+    /**
+     * Write data to file (with rewriting)
+     *
+     * @param file file
+     * @param data file data
+     */
+    public void writeFile(File file, String data) throws IOException
+    {
+        FileOutputStream fos = null;
+        try
+        {
+            fos = new FileOutputStream(file);
+            if (data != null)
+                fos.write(data.getBytes());
+        }
+        finally
+        {
+            if (fos != null)
+                try
+                {
+                    fos.close();
+                } catch (IOException e)
+                {
+                    // ignored
+                }
+        }
+    }
+
+    /**
+     * Generate unique filename
+     * @param prefix prefix
+     * @param suffix suffix
+     * @return generated unique filename
+     */
+    public String generateUniqueFileName(String prefix, String suffix)
+    {
+        StringBuilder sb = new StringBuilder();
+        if (prefix != null)
+            sb.append(prefix);
+
+        sb.append(UUID.randomUUID().toString());
+
+        if (suffix != null)
+            sb.append(suffix);
+
+        return sb.toString();
+    }
+}