Convert StringUtils to Kotlin

Keep converting utils classes.
Class StringUtils is converted from Java to Kotlin. Companion object
functions are annotated @JvmStatic in order to make them callable from
Java codebase as static methods.

android/uhabits-core/src/main/java/org/isoron/uhabits/core/utils/StringUtils.java

@@ -1,67 +0,0 @@
-/*
- * Copyright (C) 2017 Álinson Santos Xavier <isoron@gmail.com>
- *
- * This file is part of Loop Habit Tracker.
- *
- * Loop Habit Tracker is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by the
- * Free Software Foundation, either version 3 of the License, or (at your
- * option) any later version.
- *
- * Loop Habit Tracker 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 this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
-package org.isoron.uhabits.core.utils;
-
-import org.apache.commons.lang3.builder.*;
-
-import java.math.*;
-import java.util.*;
-
-public class StringUtils
-{
-    private static StandardToStringStyle toStringStyle = null;
-
-    public static String getRandomId()
-    {
-        return new BigInteger(260, new Random()).toString(32).substring(0, 32);
-    }
-
-    public static ToStringStyle defaultToStringStyle()
-    {
-        if (toStringStyle == null)
-        {
-            toStringStyle = new StandardToStringStyle();
-            toStringStyle.setFieldSeparator(", ");
-            toStringStyle.setUseClassName(false);
-            toStringStyle.setUseIdentityHashCode(false);
-            toStringStyle.setContentStart("{");
-            toStringStyle.setContentEnd("}");
-            toStringStyle.setFieldNameValueSeparator(": ");
-            toStringStyle.setArrayStart("[");
-            toStringStyle.setArrayEnd("]");
-        }
-
-        return toStringStyle;
-    }
-
-    public static String joinLongs(long values[])
-    {
-        return org.apache.commons.lang3.StringUtils.join(values, ',');
-    }
-
-    public static long[] splitLongs(String str)
-    {
-        String parts[] = org.apache.commons.lang3.StringUtils.split(str, ',');
-
-        long numbers[] = new long[parts.length];
-        for (int i = 0; i < parts.length; i++) numbers[i] = Long.valueOf(parts[i]);
-        return numbers;
-    }
-}

android/uhabits-core/src/main/java/org/isoron/uhabits/core/utils/StringUtils.kt

@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2017 Álinson Santos Xavier <isoron@gmail.com>
+ *
+ * This file is part of Loop Habit Tracker.
+ *
+ * Loop Habit Tracker is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or (at your
+ * option) any later version.
+ *
+ * Loop Habit Tracker 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 this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.isoron.uhabits.core.utils
+
+import org.apache.commons.lang3.builder.StandardToStringStyle
+import org.apache.commons.lang3.builder.ToStringStyle
+import java.math.BigInteger
+import java.util.Random
+
+class StringUtils {
+
+    companion object {
+        private lateinit var toStringStyle: StandardToStringStyle
+
+        @JvmStatic
+        fun getRandomId(): String {
+            return BigInteger(260, Random()).toString(32).subSequence(0, 32).toString()
+        }
+
+        @JvmStatic
+        fun defaultToStringStyle(): ToStringStyle {
+            toStringStyle = StandardToStringStyle()
+            toStringStyle.apply {
+                fieldSeparator = ", "
+                isUseClassName = false
+                isUseIdentityHashCode = false
+                contentStart = "{"
+                contentEnd = "}"
+                fieldNameValueSeparator = ": "
+                arrayStart = "["
+                arrayEnd = "]"
+            }
+
+            return toStringStyle
+        }
+
+        @JvmStatic
+        fun joinLongs(values: LongArray): String {
+            return org.apache.commons.lang3.StringUtils.join(values, ',')
+        }
+
+        @JvmStatic
+        fun splitLongs(str: String): LongArray {
+            val parts: Array<String> = org.apache.commons.lang3.StringUtils.split(str, ',')
+            val numbers = LongArray(parts.size) {
+                i ->
+                parts[i].toLong()
+            }
+            return numbers
+        }
+    }
+}