[str-length] string length vs string.bytes.length (#15518)

* [str-length] string length vs string.bytes.length

* [str-length] add relative path to the core-java-modules

core-java-modules/core-java-string-operations-7/src/test/java/com/baeldung/aboutlength/StringLengthAndByteArrayLengthUnitTest.java

@@ -0,0 +1,49 @@
+package com.baeldung.aboutlength;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.nio.charset.Charset;
+
+import org.junit.jupiter.api.Test;
+
+public class StringLengthAndByteArrayLengthUnitTest {
+
+    @Test
+    void whenStrWithAllAsciiChar_thenStrLengthAndBytesLengthAreEqual() {
+        String s = "beautiful";
+        assertEquals(9, s.length());
+        assertEquals(9, s.getBytes().length);
+    }
+
+    @Test
+    void whenStrWithUnicodeChar_thenStrLengthAndBytesLengthAreNotEqual() {
+        assertEquals("f6", Integer.toHexString('ö'));
+        assertEquals("7f8e", Integer.toHexString('美'));
+        assertEquals("4e3d", Integer.toHexString('丽'));
+
+        String de = "schöne";
+        assertEquals(6, de.length());
+        assertEquals(7, de.getBytes().length);
+
+        String cn = "美丽";
+        assertEquals(2, cn.length());
+        assertEquals(6, cn.getBytes().length);
+    }
+
+    @Test
+    void whenUsingUTF_32_thenBytesLengthIs4TimesStrLength() {
+        Charset UTF_32 = Charset.forName("UTF_32");
+
+        String en = "beautiful";
+        assertEquals(9, en.length());
+        assertEquals(9 * 4, en.getBytes(UTF_32).length);
+
+        String de = "schöne";
+        assertEquals(6, de.length());
+        assertEquals(6 * 4, de.getBytes(UTF_32).length);
+
+        String cn = "美丽";
+        assertEquals(2, cn.length());
+        assertEquals(2 * 4, cn.getBytes(UTF_32).length);
+    }
+}

core-java-modules/pom.xml

@@ -12,6 +12,7 @@
         <groupId>com.baeldung</groupId>
         <artifactId>parent-modules</artifactId>
         <version>1.0.0-SNAPSHOT</version>
+        <relativePath>..</relativePath>
     </parent>
 
     <modules>