From 32dba7dd0699f7581b3f871cd21ff74e1d0d526f Mon Sep 17 00:00:00 2001
From: Kai Yuan <kent.yuan@Gmail.com>
Date: Wed, 25 Nov 2020 00:03:34 +0100
Subject: [PATCH] remove file extensions

---
 .../MyFilenameUtil.java                       | 14 ++++
 .../FileNameDelExtensionUnitTest.java         | 72 +++++++++++++++++++
 2 files changed, 86 insertions(+)
 create mode 100644 core-java-modules/core-java-io-3/src/main/java/com/baeldung/filenamewithoutextension/MyFilenameUtil.java
 create mode 100644 core-java-modules/core-java-io-3/src/test/java/com/baeldung/filenamewithoutextension/FileNameDelExtensionUnitTest.java

diff --git a/core-java-modules/core-java-io-3/src/main/java/com/baeldung/filenamewithoutextension/MyFilenameUtil.java b/core-java-modules/core-java-io-3/src/main/java/com/baeldung/filenamewithoutextension/MyFilenameUtil.java
new file mode 100644
index 0000000000..102c454c49
--- /dev/null
+++ b/core-java-modules/core-java-io-3/src/main/java/com/baeldung/filenamewithoutextension/MyFilenameUtil.java
@@ -0,0 +1,14 @@
+package com.baeldung.filenamewithoutextension;
+
+public class MyFilenameUtil {
+    private MyFilenameUtil() {}
+
+    public static String removeFileExtension(String filename, boolean removeAllExtensions) {
+        if (filename == null || filename.isEmpty()) {
+            return filename;
+        }
+
+        String extPattern = "(?<!^)[.]" + (removeAllExtensions ? ".*" : "[^.]*$");
+        return filename.replaceAll(extPattern, "");
+    }
+}
diff --git a/core-java-modules/core-java-io-3/src/test/java/com/baeldung/filenamewithoutextension/FileNameDelExtensionUnitTest.java b/core-java-modules/core-java-io-3/src/test/java/com/baeldung/filenamewithoutextension/FileNameDelExtensionUnitTest.java
new file mode 100644
index 0000000000..3c5e7fbdad
--- /dev/null
+++ b/core-java-modules/core-java-io-3/src/test/java/com/baeldung/filenamewithoutextension/FileNameDelExtensionUnitTest.java
@@ -0,0 +1,72 @@
+package com.baeldung.filenamewithoutextension;
+
+import com.google.common.io.Files;
+import org.apache.commons.io.FilenameUtils;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+
+public class FileNameDelExtensionUnitTest {
+
+    @Test
+    public void givenDotFileWithoutExt_whenCallGuavaMethod_thenCannotGetDesiredResult() {
+        //negative assertion
+        assertNotEquals(".baeldung", Files.getNameWithoutExtension(".baeldung"));
+    }
+
+    @Test
+    public void givenFileWithoutMultipleExt_whenCallGuavaMethod_thenCannotRemoveAllExtensions() {
+        //negative assertion
+        assertNotEquals("baeldung", Files.getNameWithoutExtension("baeldung.tar.gz"));
+    }
+
+    @Test
+    public void givenDotFileWithoutExt_whenCallApacheCommonsMethod_thenCannotGetDesiredResult() {
+        //negative assertion
+        assertNotEquals(".baeldung", FilenameUtils.removeExtension(".baeldung"));
+    }
+
+    @Test
+    public void givenFileWithoutMultipleExt_whenCallApacheCommonsMethod_thenCannotRemoveAllExtensions() {
+        //negative assertion
+        assertNotEquals("baeldung", FilenameUtils.removeExtension("baeldung.tar.gz"));
+    }
+
+    @Test
+    public void givenFilenameNoExt_whenCallFilenameUtilMethod_thenGetExpectedFilename() {
+        assertEquals("baeldung", MyFilenameUtil.removeFileExtension("baeldung", true));
+        assertEquals("baeldung", MyFilenameUtil.removeFileExtension("baeldung", false));
+    }
+
+    @Test
+    public void givenSingleExt_whenCallFilenameUtilMethod_thenGetExpectedFilename() {
+        assertEquals("baeldung", MyFilenameUtil.removeFileExtension("baeldung.txt", true));
+        assertEquals("baeldung", MyFilenameUtil.removeFileExtension("baeldung.txt", false));
+    }
+
+
+    @Test
+    public void givenDotFile_whenCallFilenameUtilMethod_thenGetExpectedFilename() {
+        assertEquals(".baeldung", MyFilenameUtil.removeFileExtension(".baeldung", true));
+        assertEquals(".baeldung", MyFilenameUtil.removeFileExtension(".baeldung", false));
+    }
+
+    @Test
+    public void givenDotFileWithExt_whenCallFilenameUtilMethod_thenGetExpectedFilename() {
+        assertEquals(".baeldung", MyFilenameUtil.removeFileExtension(".baeldung.conf", true));
+        assertEquals(".baeldung", MyFilenameUtil.removeFileExtension(".baeldung.conf", false));
+    }
+
+    @Test
+    public void givenDoubleExt_whenCallFilenameUtilMethod_thenGetExpectedFilename() {
+        assertEquals("baeldung", MyFilenameUtil.removeFileExtension("baeldung.tar.gz", true));
+        assertEquals("baeldung.tar", MyFilenameUtil.removeFileExtension("baeldung.tar.gz", false));
+    }
+
+    @Test
+    public void givenDotFileWithDoubleExt_whenCallFilenameUtilMethod_thenGetExpectedFilename() {
+        assertEquals(".baeldung", MyFilenameUtil.removeFileExtension(".baeldung.conf.bak", true));
+        assertEquals(".baeldung.conf", MyFilenameUtil.removeFileExtension(".baeldung.conf.bak", false));
+    }
+}