Fix some NullPointerException on StringUtils.implode method

Author: kwiky

README.md

@@ -15,7 +15,7 @@ allprojects {
 Step 2. Add the dependency
 ```
 dependencies {
-    compile "com.github.playmoweb:library-android-utils:1.0.2"
+    compile "com.github.playmoweb:library-android-utils:1.0.3"
 }
 ```
 

android-utils/build.gradle

@@ -7,7 +7,7 @@ android {
         minSdkVersion 16
         targetSdkVersion 27
         versionCode 1
-        versionName "1.0.2"
+        versionName "1.0.3"
     }
 }
 

android-utils/src/main/java/com/playmoweb/android/utils/StringUtils.java

@@ -16,6 +16,7 @@ public class StringUtils {
 
     /**
      * Returns true if the string is null or 0-length.
+     *
      * @param str the string to be examined
      * @return true if str is null or zero length
      */
@@ -50,14 +51,14 @@ public static String implode(final String separator, final Collection<String> da
 
     public static String implode(final String separator, final String... data) {
         final StringBuilder sb = new StringBuilder();
-        for (int i = 0; i < data.length - 1; i++) {
+        for (int i = 0; i < data.length; i++) {
             if (!isEmpty(data[i]) && !data[i].matches(" *")) {//empty string are ""; " "; "  "; and so on
+                if (!isEmpty(sb.toString())) {
+                    sb.append(separator);
+                }
                 sb.append(data[i]);
-                sb.append(separator);
             }
         }
-        //data.length - 1 => to not add separator at the end
-        sb.append(data[data.length - 1].trim());
         return sb.toString();
     }
 }

android-utils/src/test/java/com/playmoweb/android/utils/StringUtilsTest.java

@@ -39,5 +39,11 @@ public void testImplodeList() {
     public void testImplodeWithNull() {
         String result = StringUtils.implode(", ", "test1", null, "test2");
         assertEquals("test1, test2", result);
+        result = StringUtils.implode(", ", "test1", "test2", null);
+        assertEquals("test1, test2", result);
+        result = StringUtils.implode(", ", null, "test1", "test2");
+        assertEquals("test1, test2", result);
+        result = StringUtils.implode(", ", null, "test1", null, "test2", null);
+        assertEquals("test1, test2", result);
     }
 }