perf: avoid backtracking in regex

Author: javier-godoy

src/main/java/com/flowingcode/vaadin/addons/demo/MultiSourceCodeViewer.java

@@ -43,14 +43,15 @@ private Tab[] createTabs(List<SourceCodeTab> sourceCodeTabs) {
   private Tab createTab(SourceCodeTab sourceCodeTab) {
     String url = sourceCodeTab.getUrl();
     String language = sourceCodeTab.getLanguage();
-
     String caption = sourceCodeTab.getCaption();
+
+    String filename = getFilename(url);
     if (caption == null) {
-      caption = url.replaceAll(".*/", "");
+      caption = filename;
     }
 
     if (language == null) {
-      String ext = url.replaceAll(".*\\.", "");
+      String ext = getExtension(filename);
       switch (ext) {
         case "java":
           language = "java";
@@ -76,6 +77,16 @@ private Tab createTab(SourceCodeTab sourceCodeTab) {
     return tab;
   }
 
+  private String getFilename(String url) {
+    int i = url.lastIndexOf('/');
+    return i >= 0 ? url.substring(i + 1) : url;
+  }
+
+  private String getExtension(String filename) {
+    int i = filename.lastIndexOf('.');
+    return i >= 0 ? filename.substring(i + 1) : filename;
+  }
+
   private void onTabSelected(Tab tab) {
     String url = (String) ComponentUtil.getData(tab, DATA_URL);
     String language = (String) ComponentUtil.getData(tab, DATA_LANGUAGE);