BAEL-838 Refactord code with Java8 examples. (#1833)

* Code for Dependency Injection Article.

* Added Java based configuration. Downloaded formatter.xml and reformatted
all changed files. Manually changed tab into 4 spaces in XML
configuration files.

* BAEL-434 - Spring Roo project files generated by Spring Roo. No
formatting applied. Added POM, java and resources folders.

* Moved project from roo to spring-roo folder.

* BAEL-838 Initial code showing how to remove last char - helper class and tests.

* BAEL-838 Corrected Helper class and associated empty string test case. Added StringUtils.substing tests.

* BAEL-838 Refromatted code using formatter.xml. Added Assert.assertEquals import. Renamed test to follow convention. Reordered tests.

* BAEL-838 - Added regex method and updated tests.

* BAEL-838 Added new line examples.

* BAEL-838 Renamed RemoveLastChar class to StringHelper and added Java8 examples. Refactord code.

* BAEL-838 Changed method names

core-java/src/main/java/com/baeldung/string/RemoveLastChar.java

@@ -1,19 +0,0 @@
-package com.baeldung.string;
-
-public class RemoveLastChar {
-    public static String substring(String s) {
-        if (s == null || s.length() == 0) {
-            return s;
-        } else {
-            return (s.substring(0, s.length() - 1));
-        }
-    }
-
-    public static String chop(String s) {
-        if (s == null) {
-            return s;
-        } else {
-            return s.replaceAll(".$", "");
-        }
-    }
-}

core-java/src/main/java/com/baeldung/string/StringHelper.java

@@ -0,0 +1,26 @@
+package com.baeldung.string;
+
+import java.util.Optional;
+
+public class StringHelper {
+    public static String removeLastChar(String s) {
+        return (s == null || s.length() == 0) ? s : (s.substring(0, s.length() - 1));
+    }
+
+    public static String removeLastCharRegex(String s) {
+        return (s == null) ? s : s.replaceAll(".$", "");
+    }
+
+    public static String removeLastCharOptional(String s) {
+        return Optional.ofNullable(s)
+            .filter(str -> str.length() != 0)
+            .map(str -> str.substring(0, str.length() - 1))
+            .orElse(s);
+    }
+
+    public static String removeLastCharRegexOptional(String s) {
+        return Optional.ofNullable(s)
+            .map(str -> str.replaceAll(".$", ""))
+            .orElse(null);
+    }
+}

core-java/src/test/java/com/baeldung/string/StringHelperTest.java

@@ -5,7 +5,7 @@ import static org.junit.Assert.assertNotEquals;
 import org.apache.commons.lang3.StringUtils;
 import org.junit.Test;
 
-public class RemoveLastCharTest {
+public class StringHelperTest {
 
     public static final String TEST_STRING = "abcdef";
     public static final String NULL_STRING = null;
@@ -17,62 +17,76 @@ public class RemoveLastCharTest {
 
     @Test
     public void givenTestString_whenSubstring_thenGetStingWithoutLastChar() {
-        assertEquals("abcde", RemoveLastChar.substring(TEST_STRING));
+        assertEquals("abcde", StringHelper.removeLastChar(TEST_STRING));
         assertEquals("abcde", StringUtils.substring(TEST_STRING, 0, TEST_STRING.length() - 1));
         assertEquals("abcde", StringUtils.chop(TEST_STRING));
         assertEquals("abcde", TEST_STRING.replaceAll(".$", ""));
-        assertEquals("abcde", RemoveLastChar.chop(TEST_STRING));
+        assertEquals("abcde", StringHelper.removeLastCharRegex(TEST_STRING));
+        assertEquals("abcde", StringHelper.removeLastCharOptional(TEST_STRING));
+        assertEquals("abcde", StringHelper.removeLastCharRegexOptional(TEST_STRING));
     }
 
     @Test
     public void givenNullString_whenSubstring_thenGetNullString() {
-        assertEquals(NULL_STRING, RemoveLastChar.substring(NULL_STRING));
+        assertEquals(NULL_STRING, StringHelper.removeLastChar(NULL_STRING));
         assertEquals(NULL_STRING, StringUtils.chop(NULL_STRING));
-        assertEquals(NULL_STRING, RemoveLastChar.chop(NULL_STRING));
+        assertEquals(NULL_STRING, StringHelper.removeLastCharRegex(NULL_STRING));
+        assertEquals(NULL_STRING, StringHelper.removeLastCharOptional(NULL_STRING));
+        assertEquals(NULL_STRING, StringHelper.removeLastCharRegexOptional(NULL_STRING));
     }
 
     @Test
     public void givenEmptyString_whenSubstring_thenGetEmptyString() {
-        assertEquals(EMPTY_STRING, RemoveLastChar.substring(EMPTY_STRING));
+        assertEquals(EMPTY_STRING, StringHelper.removeLastChar(EMPTY_STRING));
         assertEquals(EMPTY_STRING, StringUtils.substring(EMPTY_STRING, 0, EMPTY_STRING.length() - 1));
         assertEquals(EMPTY_STRING, StringUtils.chop(EMPTY_STRING));
         assertEquals(EMPTY_STRING, EMPTY_STRING.replaceAll(".$", ""));
-        assertEquals(EMPTY_STRING, RemoveLastChar.chop(EMPTY_STRING));
+        assertEquals(EMPTY_STRING, StringHelper.removeLastCharRegex(EMPTY_STRING));
+        assertEquals(EMPTY_STRING, StringHelper.removeLastCharOptional(EMPTY_STRING));
+        assertEquals(EMPTY_STRING, StringHelper.removeLastCharRegexOptional(EMPTY_STRING));
     }
 
     @Test
     public void givenOneCharString_whenSubstring_thenGetEmptyString() {
-        assertEquals(EMPTY_STRING, RemoveLastChar.substring(ONE_CHAR_STRING));
+        assertEquals(EMPTY_STRING, StringHelper.removeLastChar(ONE_CHAR_STRING));
         assertEquals(EMPTY_STRING, StringUtils.substring(ONE_CHAR_STRING, 0, ONE_CHAR_STRING.length() - 1));
         assertEquals(EMPTY_STRING, StringUtils.chop(ONE_CHAR_STRING));
         assertEquals(EMPTY_STRING, ONE_CHAR_STRING.replaceAll(".$", ""));
-        assertEquals(EMPTY_STRING, RemoveLastChar.chop(ONE_CHAR_STRING));
+        assertEquals(EMPTY_STRING, StringHelper.removeLastCharRegex(ONE_CHAR_STRING));
+        assertEquals(EMPTY_STRING, StringHelper.removeLastCharOptional(ONE_CHAR_STRING));
+        assertEquals(EMPTY_STRING, StringHelper.removeLastCharRegexOptional(ONE_CHAR_STRING));
     }
 
     @Test
     public void givenStringWithWhiteSpaceAtTheEnd_whenSubstring_thenGetStringWithoutWhiteSpaceAtTheEnd() {
-        assertEquals("abc", RemoveLastChar.substring(WHITE_SPACE_AT_THE_END_STRING));
+        assertEquals("abc", StringHelper.removeLastChar(WHITE_SPACE_AT_THE_END_STRING));
         assertEquals("abc", StringUtils.substring(WHITE_SPACE_AT_THE_END_STRING, 0, WHITE_SPACE_AT_THE_END_STRING.length() - 1));
         assertEquals("abc", StringUtils.chop(WHITE_SPACE_AT_THE_END_STRING));
         assertEquals("abc", WHITE_SPACE_AT_THE_END_STRING.replaceAll(".$", ""));
-        assertEquals("abc", RemoveLastChar.chop(WHITE_SPACE_AT_THE_END_STRING));
+        assertEquals("abc", StringHelper.removeLastCharRegex(WHITE_SPACE_AT_THE_END_STRING));
+        assertEquals("abc", StringHelper.removeLastCharOptional(WHITE_SPACE_AT_THE_END_STRING));
+        assertEquals("abc", StringHelper.removeLastCharRegexOptional(WHITE_SPACE_AT_THE_END_STRING));
     }
     
     @Test
     public void givenStringWithNewLineAtTheEnd_whenSubstring_thenGetStringWithoutNewLine() {
-        assertEquals("abc", RemoveLastChar.substring(NEW_LINE_AT_THE_END_STRING));
+        assertEquals("abc", StringHelper.removeLastChar(NEW_LINE_AT_THE_END_STRING));
         assertEquals("abc", StringUtils.substring(NEW_LINE_AT_THE_END_STRING, 0, NEW_LINE_AT_THE_END_STRING.length() - 1));
         assertEquals("abc", StringUtils.chop(NEW_LINE_AT_THE_END_STRING));
         assertNotEquals("abc", NEW_LINE_AT_THE_END_STRING.replaceAll(".$", ""));
-        assertNotEquals("abc", RemoveLastChar.chop(NEW_LINE_AT_THE_END_STRING));
+        assertNotEquals("abc", StringHelper.removeLastCharRegex(NEW_LINE_AT_THE_END_STRING));
+        assertEquals("abc", StringHelper.removeLastCharOptional(NEW_LINE_AT_THE_END_STRING));
+        assertNotEquals("abc", StringHelper.removeLastCharRegexOptional(NEW_LINE_AT_THE_END_STRING));
     }
     
     @Test
     public void givenMultiLineString_whenSubstring_thenGetStringWithoutNewLine() {
-        assertEquals("abc\nde", RemoveLastChar.substring(MULTIPLE_LINES_STRING));
+        assertEquals("abc\nde", StringHelper.removeLastChar(MULTIPLE_LINES_STRING));
         assertEquals("abc\nde", StringUtils.substring(MULTIPLE_LINES_STRING, 0, MULTIPLE_LINES_STRING.length() - 1));
         assertEquals("abc\nde", StringUtils.chop(MULTIPLE_LINES_STRING));
         assertEquals("abc\nde", MULTIPLE_LINES_STRING.replaceAll(".$", ""));
-        assertEquals("abc\nde", RemoveLastChar.chop(MULTIPLE_LINES_STRING));
+        assertEquals("abc\nde", StringHelper.removeLastCharRegex(MULTIPLE_LINES_STRING));
+        assertEquals("abc\nde", StringHelper.removeLastCharOptional(MULTIPLE_LINES_STRING));
+        assertEquals("abc\nde", StringHelper.removeLastCharRegexOptional(MULTIPLE_LINES_STRING));
     }
 }