[extractFilename] Getting the Filename From a String Containing an Absolute File Path (#12728)

core-java-modules/core-java-io-4/src/test/java/com/baeldung/filename/ExtractFilenameUnitTest.java

@@ -0,0 +1,66 @@
+package com.baeldung.filename;
+
+import org.apache.commons.io.FilenameUtils;
+import org.junit.jupiter.api.Test;
+
+import java.io.File;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+
+class ExtractFilenameUnitTest {
+
+    private static final String PATH_LINUX = "/root/with space/subDir/myFile.linux";
+    private static final String EXPECTED_FILENAME_LINUX = "myFile.linux";
+
+    private static final String PATH_WIN = "C:\\root\\with space\\subDir\\myFile.win";
+    private static final String EXPECTED_FILENAME_WIN = "myFile.win";
+
+
+    @Test
+    void givenAbsolutePath_whenExtractingFilenameAsString_thenGetTheFilename() {
+        int index = PATH_LINUX.lastIndexOf(File.separator);
+        String filenameLinux = PATH_LINUX.substring(index + 1);
+        assertEquals(EXPECTED_FILENAME_LINUX, filenameLinux);
+
+        // only works on Windows system:
+        //int index = PATH_WIN.lastIndexOf(File.pathSeparator);
+        //String filenameWin = PATH_WIN.substring(index + 1);
+        //assertEquals(EXPECTED_FILENAME_WIN, filenameWin);
+    }
+
+
+    @Test
+    void givenAbsolutePath_whenUsingFileGetName_thenGetTheFilename() {
+        File fileLinux = new File(PATH_LINUX);
+        assertEquals(EXPECTED_FILENAME_LINUX, fileLinux.getName());
+
+        // only works on Windows system:
+        // File fileWin = new File(PATH_WIN);
+        // assertEquals(EXPECTED_FILENAME_WIN, fileWin.getName());
+    }
+
+    @Test
+    void givenAbsolutePath_whenUsingPath_thenGetTheFilename() {
+        Path pathLinux = Paths.get(PATH_LINUX);
+        assertEquals(EXPECTED_FILENAME_LINUX, pathLinux.getFileName().toString());
+
+        // only works on Windows system:
+        // Path pathWin = Paths.get(PATH_WIN);
+        // assertEquals(EXPECTED_FILENAME_WIN, pathWin.getFileName().toString());
+    }
+
+    @Test
+    void givenAbsolutePath_whenUsingFilenameUtils_thenGetTheFilename() {
+        String filenameLinux = FilenameUtils.getName(PATH_LINUX);
+        assertEquals(EXPECTED_FILENAME_LINUX, filenameLinux);
+
+        String filenameWin = FilenameUtils.getName(PATH_WIN);
+        assertEquals(EXPECTED_FILENAME_WIN, filenameWin);
+
+        String filenameToBreak = FilenameUtils.getName("/root/somedir/magic\\file.txt");
+        assertNotEquals("magic\\file.txt", filenameToBreak); // <-- filenameToBreak = "file.txt", but we expect: magic\file.txt
+    }
+}