[unicode-from-number] BAEL-5832 (#15689)

core-java-modules/core-java-char/src/test/java/com/baeldung/unicodechar/UnicodeCharFromCodePointHexStringUnitTest.java

@@ -0,0 +1,70 @@
+package com.baeldung.unicodechar;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class UnicodeCharFromCodePointHexStringUnitTest {
+    private static final String U_CHECK = "✅"; // U+2705
+    private static final String U_STRONG = "强"; // U+5F3A
+
+
+    @Test
+    void whenEscapeUAndNumberInString_thenGetExpectedUnicodeStr() {
+        String check = "\u2705";
+        assertEquals(U_CHECK, check);
+
+        String strong = "\u5F3A";
+        assertEquals(U_STRONG, strong);
+
+        // "A" U+0041
+        assertEquals("A", "\u0041");
+    }
+
+
+    @Test
+    void whenConcatUAndNumberAsString_thenDoNotGetExpectedUnicodeStr() {
+        String check = "\\u" + "2705";
+        assertEquals("\\u2705", check);
+
+        String strong = "\\u" + "5F3A";
+        assertEquals("\\u5F3A", strong);
+    }
+
+
+    @Test
+    void whenCastHexCodePointToCharAndConvertCharToString_thenGetExpectedUnicodeStr() {
+
+        int codePoint = Integer.parseInt("2705", 16); //Decimal int: 9989
+        char[] checkChar = Character.toChars(codePoint);
+        String check = String.valueOf(checkChar);
+        assertEquals(U_CHECK, check);
+
+        // For Java 11 and later versions
+        // assertEquals(U_CHECK, Character.toString(codePoint));
+
+        codePoint = Integer.parseInt("5F3A", 16); //Decimal int: 24378
+        char[] strongChar = Character.toChars(codePoint);
+        String strong = String.valueOf(strongChar);
+        assertEquals(U_STRONG, strong);
+
+        // For Java 11 and later versions
+        // assertEquals(U_STRONG, Character.toString(codePoint));
+    }
+
+    String stringFromCodePointHex(String codePointHex) {
+        int codePoint = Integer.parseInt(codePointHex, 16);
+
+        // For Java 11 and later versions: return Character.toString(codePoint)
+
+        char[] chars = Character.toChars(codePoint);
+        return String.valueOf(chars);
+    }
+
+    @Test
+    void whenUsingstringFromCodePointHex_thenGetExpectedUnicodeStr() {
+        assertEquals("A", stringFromCodePointHex("0041"));
+        assertEquals(U_CHECK, stringFromCodePointHex("2705"));
+        assertEquals(U_STRONG, stringFromCodePointHex("5F3A"));
+    }
+}