Extract file extension: Difference between revisions

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@@ Line 1,385: / Line 1,385: @@
 =={{header|Java}}==
-<syntaxhighlight lang="java">public class Test {
+<syntaxhighlight lang="java">
+import java.io.File;
+</syntaxhighlight>
-    public static void main(String[] args) {
+<syntaxhighlight lang="java">
-        String[] filenames = { "http://example.com/download.tar.gz",
+public static void main(String[] args) {
-                               "CharacterModel.3DS",
+    String[] strings = {
-                               ".desktop",
+        "http://example.com/download.tar.gz",
-                               "document",
-                               "document.txt_backup",
+        "CharacterModel.3DS",
-                               "/etc/pam.d/login"
+        ".desktop",
-        };
+        "document",
+        "document.txt_backup",
+        "/etc/pam.d/login",
+    };
+    for (String string : strings)
+        System.out.println(extractExtension(string));
+}
-        for (String filename : filenames) {
+static String extractExtension(String string) {
-            String ext = "null";
+    /* we can use the 'File' class to extract the file-name */
+    File file = new File(string);
-            int idx = filename.lastIndexOf('.');
+    String filename = file.getName();
-            if (idx != -1) {
-                String tmp = filename.substring(idx);
+    int indexOf = filename.lastIndexOf('.');
+    if (indexOf != -1) {
-                if (tmp.matches("\\.[a-zA-Z0-9]+")) {
-                    ext = tmp;
+        String extension = filename.substring(indexOf);
-                }
+        /* and use a regex to match only valid extensions */
+        if (extension.matches("\\.[A-Za-z\\d]+"))
-            }
-            System.out.println(filename + " -> " + ext);
+            return extension;
-        }
     }
+    return "";
-}</syntaxhighlight>
+}
+</syntaxhighlight>
 {{Out}}
+<pre>
-<pre>http://example.com/download.tar.gz -> .gz
+.gz
-CharacterModel.3DS -> .3DS
+.3DS
-.desktop -> .desktop
+.desktop
-document -> null
-document.txt_backup -> null
-/etc/pam.d/login -> null</pre>
+</pre>
 =={{header|javascript}}==