Add EndianConverter algorithm (#5751)

Author: Hardvan

DIRECTORY.md

@@ -89,6 +89,7 @@
             * [DecimalToBinary](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/conversions/DecimalToBinary.java)
             * [DecimalToHexadecimal](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/conversions/DecimalToHexadecimal.java)
             * [DecimalToOctal](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/conversions/DecimalToOctal.java)
+            * [EndianConverter](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/conversions/EndianConverter.java)
             * [HexaDecimalToBinary](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/conversions/HexaDecimalToBinary.java)
             * [HexaDecimalToDecimal](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/conversions/HexaDecimalToDecimal.java)
             * [HexToOct](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/conversions/HexToOct.java)
@@ -728,6 +729,7 @@
             * [DecimalToBinaryTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/conversions/DecimalToBinaryTest.java)
             * [DecimalToHexadecimalTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/conversions/DecimalToHexadecimalTest.java)
             * [DecimalToOctalTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/conversions/DecimalToOctalTest.java)
+            * [EndianConverterTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/conversions/EndianConverterTest.java)
             * [HexaDecimalToBinaryTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/conversions/HexaDecimalToBinaryTest.java)
             * [HexaDecimalToDecimalTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/conversions/HexaDecimalToDecimalTest.java)
             * [HexToOctTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/conversions/HexToOctTest.java)

src/main/java/com/thealgorithms/conversions/EndianConverter.java

@@ -0,0 +1,23 @@
+package com.thealgorithms.conversions;
+
+/**
+ * Converts between big-endian and little-endian formats.
+ * Big-endian is the most significant byte first, while little-endian is the least significant byte first.
+ * Big-endian to little-endian: 0x12345678 -> 0x78563412
+ *
+ * Little-endian to big-endian: 0x12345678 -> 0x78563412
+ *
+ * @author Hardvan
+ */
+public final class EndianConverter {
+    private EndianConverter() {
+    }
+
+    public static int bigToLittleEndian(int value) {
+        return Integer.reverseBytes(value);
+    }
+
+    public static int littleToBigEndian(int value) {
+        return Integer.reverseBytes(value);
+    }
+}

src/test/java/com/thealgorithms/conversions/EndianConverterTest.java

@@ -0,0 +1,22 @@
+package com.thealgorithms.conversions;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class EndianConverterTest {
+
+    @Test
+    public void testBigToLittleEndian() {
+        assertEquals(0x78563412, EndianConverter.bigToLittleEndian(0x12345678));
+        assertEquals(0x00000000, EndianConverter.bigToLittleEndian(0x00000000));
+        assertEquals(0x00000001, EndianConverter.bigToLittleEndian(0x01000000));
+    }
+
+    @Test
+    public void testLittleToBigEndian() {
+        assertEquals(0x12345678, EndianConverter.littleToBigEndian(0x78563412));
+        assertEquals(0x00000000, EndianConverter.littleToBigEndian(0x00000000));
+        assertEquals(0x01000000, EndianConverter.littleToBigEndian(0x00000001));
+    }
+}